From n3drk@bellsouth.net Sun May 4 20:46:51 2003 From: n3drk@bellsouth.net (n3drk) Date: Sun, 4 May 2003 15:46:51 -0400 Subject: [Antennas] test Message-ID: <000d01c31275$e88dda30$6001a8c0@n3drk> From sm5dqc@algonet.se Sun May 4 22:28:07 2003 From: sm5dqc@algonet.se (Osten B Magnusson) Date: Sun, 4 May 2003 23:28:07 +0200 Subject: [Antennas] Questions! Message-ID: <000201c31284$2d1c0560$ec287f3e@g1b8u4> Friends! I was on this list some years ago and now I'm back again! A question or two: I'm living on an urban lot less than 1000 square meters, and no space for more than one tower. I have been using an=20 inverted vee for a couple of years on 80 meter CW, more than 230 DXCC-''entities'' worked, and now I'm going to use it also on 17, 30, 80 CW - 3500 - 3225, 80 SSB 3575 - 3580 and 160 meters. My idea is to have relays in each leg adding lengths when going from higher to lower frequencies. In this case it means 4 relays in each leg, totally 8 relays. As there is high voltage in the ends of the legs what kind of light-weight relays can I use, not too expensive and easy to get? How will the 12 or 24 Volt DC lines to the relays affect the antenna? I think you may say it's simpler to use an antenna tuner but NO, I don't like them... Would like to get your answers to the questions and also of course your opinion to the whole idea, thanks in advance. By the way, I'm a DX'er but everything worked on 40, 20 and 10 meters, 12 is going to die, so no need for those bands. I would like to put up a monoband beam for 30 meters but the problem is to have that at 70 feet as I need a support higher than that to get the beam rotatable inside the inverted vee, probably impossible! Hope to hear from you, all the best and 73 de Osten SM5DQC sm5dqc@algonet.se From DELSONCOMM@aol.com Sun May 4 22:29:25 2003 From: DELSONCOMM@aol.com (DELSONCOMM@aol.com) Date: Sun, 4 May 2003 17:29:25 EDT Subject: [Antennas] cl33 antenna mosley Message-ID: <148.10c071a5.2be6e035@aol.com> hello i need some info if possibel to add to cl33 from mosley the WARC band what need to be done please . 2nd did any one know of this antenna for receiving DX500 ? ANY ONE USE IT OUT THERE I LIKE TO KNOW HOW GOOD IS IT the web page for it is www.funkempfang.de/dx500.pdf many thanks Ody 4Z4KA --- StripMime Report -- processed MIME parts --- multipart/alternative text/plain (text body -- kept) text/html The reason this message is shown is because the post was in HTML or had an attachment. Attachments are not allowed. To learn how to post in Plain-Text go to: http://www.expita.com/nomime.html --- From w9dmk@crosslink.net Mon May 5 00:07:26 2003 From: w9dmk@crosslink.net (Robert Lay (W9DMK)) Date: Sun, 4 May 2003 19:07:26 -0400 Subject: [Antennas] Questions! References: <000201c31284$2d1c0560$ec287f3e@g1b8u4> Message-ID: <000e01c31292$cedbc3a0$0100a8c0@monster> Dear Osten, It's a totally ridiculous idea and isn't worth even trying. As you say, the voltage is very high (the current is also very low) at the ends of a dipole. Therefore, there isn't a relay in existence that can help you there. Did it ever occur to you that if such an idea had any chance at all, someone would have already tried it and published the results? In fact, the only antennas that I have ever heard of that use relays, use the relay or relays for switching in the transmission line - hopefully, at a point where the current and voltage are consistent with the capability of the relay. There is no good reason for having a dipole be one half wavelength other than a fascination for a particular radiation pattern. You still put all of the energry into space - somewhere - unless there is an efficiency issue, in which case you deal with the efficiency issue - not the length of the radiator. Tuners are not bad - you should get used to that and embrace the idea - it works for everyone else. 73 de W9DMK (Bob Lay in Dahlgren, VA http://www.qsl.net/w9dmk ----- Original Message ----- From: "Osten B Magnusson" To: Sent: Sunday, May 04, 2003 5:28 PM Subject: [Antennas] Questions! Friends! I was on this list some years ago and now I'm back again! A question or two: I'm living on an urban lot less than 1000 square meters, and no space for more than one tower. I have been using an inverted vee for a couple of years on 80 meter CW, more than 230 DXCC-''entities'' worked, and now I'm going to use it also on 17, 30, 80 CW - 3500 - 3225, 80 SSB 3575 - 3580 and 160 meters. My idea is to have relays in each leg adding lengths when going from higher to lower frequencies. In this case it means 4 relays in each leg, totally 8 relays. As there is high voltage in the ends of the legs what kind of light-weight relays can I use, not too expensive and easy to get? How will the 12 or 24 Volt DC lines to the relays affect the antenna? I think you may say it's simpler to use an antenna tuner but NO, I don't like them... Would like to get your answers to the questions and also of course your opinion to the whole idea, thanks in advance. By the way, I'm a DX'er but everything worked on 40, 20 and 10 meters, 12 is going to die, so no need for those bands. I would like to put up a monoband beam for 30 meters but the problem is to have that at 70 feet as I need a support higher than that to get the beam rotatable inside the inverted vee, probably impossible! Hope to hear from you, all the best and 73 de Osten SM5DQC sm5dqc@algonet.se - - - Your moderator for this list is: Larry Wilson KE1HZ antennas-owner@mailman.qth.net _______________________________________________ Antennas mailing list Antennas@mailman.qth.net http://mailman.qth.net/mailman/listinfo/antennas From jluthy@worldnet.att.net Mon May 5 00:35:19 2003 From: jluthy@worldnet.att.net (John Luthy) Date: Sun, 4 May 2003 16:35:19 -0700 Subject: [Antennas] Questions! References: <000201c31284$2d1c0560$ec287f3e@g1b8u4> Message-ID: <000b01c31295$d3c2ec60$c942500c@ibm0000000> An intersting thought, However I have a question, How do you plan to prevent the RF from coupling with the wires to feed the relay coils? Don't give up on your idea, I suspect that the guy that invented the SteppIR antenna had quite a few nay-sayers as he was developing his plan. Good Luck KF6QCQ ----- Original Message ----- From: "Osten B Magnusson" To: Sent: Sunday, May 04, 2003 2:28 PM Subject: [Antennas] Questions! Friends! I was on this list some years ago and now I'm back again! A question or two: I'm living on an urban lot less than 1000 square meters, and no space for more than one tower. I have been using an inverted vee for a couple of years on 80 meter CW, more than 230 DXCC-''entities'' worked, and now I'm going to use it also on 17, 30, 80 CW - 3500 - 3225, 80 SSB 3575 - 3580 and 160 meters. My idea is to have relays in each leg adding lengths when going from higher to lower frequencies. In this case it means 4 relays in each leg, totally 8 relays. As there is high voltage in the ends of the legs what kind of light-weight relays can I use, not too expensive and easy to get? How will the 12 or 24 Volt DC lines to the relays affect the antenna? I think you may say it's simpler to use an antenna tuner but NO, I don't like them... Would like to get your answers to the questions and also of course your opinion to the whole idea, thanks in advance. By the way, I'm a DX'er but everything worked on 40, 20 and 10 meters, 12 is going to die, so no need for those bands. I would like to put up a monoband beam for 30 meters but the problem is to have that at 70 feet as I need a support higher than that to get the beam rotatable inside the inverted vee, probably impossible! Hope to hear from you, all the best and 73 de Osten SM5DQC sm5dqc@algonet.se - - - Your moderator for this list is: Larry Wilson KE1HZ antennas-owner@mailman.qth.net _______________________________________________ Antennas mailing list Antennas@mailman.qth.net http://mailman.qth.net/mailman/listinfo/antennas From k5iid@ntelos.net Mon May 5 01:13:12 2003 From: k5iid@ntelos.net (Tom Horton) Date: Mon, 05 May 2003 00:13:12 +0000 Subject: [Antennas] Questions! In-Reply-To: <000201c31284$2d1c0560$ec287f3e@g1b8u4> Message-ID: <4.3.2.7.1.20030505001032.00b79100@wvinbox.ntelos.net> Osten, Why not build dipoles for each band and feed them with the same feedline. Lots of us have been doing this for many years. You don't have to have a tuner, they can be tuned just fine if you have the patience. Relays on an antenna wire seems kind of shaky. Good luck, Tom K5IID At 23:28 5/4/03 +0200, Osten B Magnusson wrote: >Friends! > >I was on this list some years ago and now I'm back again! >A question or two: > >I'm living on an urban lot less than 1000 square meters, and >no space for more than one tower. I have been using an >inverted vee for a couple of years on 80 meter CW, more >than 230 DXCC-''entities'' worked, and now I'm going to use >it also on 17, 30, 80 CW - 3500 - 3225, 80 SSB 3575 - 3580 >and 160 meters. My idea is to have relays in each leg adding >lengths when going from higher to lower frequencies. In this >case it means 4 relays in each leg, totally 8 relays. > >As there is high voltage in the ends of the legs what kind of >light-weight relays can I use, not too expensive and easy to >get? > >How will the 12 or 24 Volt DC lines to the relays affect the >antenna? > >I think you may say it's simpler to use an antenna tuner but >NO, I don't like them... > >Would like to get your answers to the questions and also >of course your opinion to the whole idea, thanks in advance. > >By the way, I'm a DX'er but everything worked on 40, 20 and >10 meters, 12 is going to die, so no need for those bands. >I would like to put up a monoband beam for 30 meters but the >problem is to have that at 70 feet as I need a support higher >than that to get the beam rotatable inside the inverted vee, >probably impossible! > >Hope to hear from you, all the best and 73 de > >Osten SM5DQC sm5dqc@algonet.se > > >- - - > >Your moderator for this list is: >Larry Wilson KE1HZ antennas-owner@mailman.qth.net >_______________________________________________ >Antennas mailing list >Antennas@mailman.qth.net >http://mailman.qth.net/mailman/listinfo/antennas "E" Sorter for the ARRL W5 QSL Bureau Williamstown, WV From TMCsail@sbcglobal.net Mon May 5 01:21:19 2003 From: TMCsail@sbcglobal.net (Tom Crawford) Date: Sun, 4 May 2003 20:21:19 -0400 Subject: [Antennas] Questions! References: <000201c31284$2d1c0560$ec287f3e@g1b8u4> Message-ID: <003501c3129c$405e35e0$6501a8c0@TOMDELL> I am sure this is a dumb question: I am not only new to this mail list but a relatively new ham: What does "12 is going to die" mean? Is this a propagation issue or a legal issue? thanks, Tom P.S. Osten - I am new to Ham radio but just from an Electrical Eng point of view, IMHO this idea sounds like a nonstarter (for many of the points you bring up). Why don't ya learn to like tuners - a matched system is a happy system ;) best of luck 73 ----- Original Message ----- From: "Osten B Magnusson" To: Sent: Sunday, May 04, 2003 5:28 PM Subject: [Antennas] Questions! Friends! I was on this list some years ago and now I'm back again! A question or two: I'm living on an urban lot less than 1000 square meters, and no space for more than one tower. I have been using an inverted vee for a couple of years on 80 meter CW, more than 230 DXCC-''entities'' worked, and now I'm going to use it also on 17, 30, 80 CW - 3500 - 3225, 80 SSB 3575 - 3580 and 160 meters. My idea is to have relays in each leg adding lengths when going from higher to lower frequencies. In this case it means 4 relays in each leg, totally 8 relays. As there is high voltage in the ends of the legs what kind of light-weight relays can I use, not too expensive and easy to get? How will the 12 or 24 Volt DC lines to the relays affect the antenna? I think you may say it's simpler to use an antenna tuner but NO, I don't like them... Would like to get your answers to the questions and also of course your opinion to the whole idea, thanks in advance. By the way, I'm a DX'er but everything worked on 40, 20 and 10 meters, 12 is going to die, so no need for those bands. I would like to put up a monoband beam for 30 meters but the problem is to have that at 70 feet as I need a support higher than that to get the beam rotatable inside the inverted vee, probably impossible! Hope to hear from you, all the best and 73 de Osten SM5DQC sm5dqc@algonet.se - - - Your moderator for this list is: Larry Wilson KE1HZ antennas-owner@mailman.qth.net _______________________________________________ Antennas mailing list Antennas@mailman.qth.net http://mailman.qth.net/mailman/listinfo/antennas From n4sl@yahoo.com Mon May 5 02:24:18 2003 From: n4sl@yahoo.com (Steve L.) Date: Sun, 4 May 2003 18:24:18 -0700 (PDT) Subject: [Antennas] Questions! In-Reply-To: <003501c3129c$405e35e0$6501a8c0@TOMDELL> Message-ID: <20030505012418.6478.qmail@web40803.mail.yahoo.com> Hi Tom, "12 is going to die" means the 12 meter band's propagation will be poor during the 11-year sunspot cycle decline. In a year or two, propagation above 21MHz will be pretty crappy. Now, if he'd said "12 ARE going to die" I would have been more worried! Wanting to be #13, Steve N4SL --- Tom Crawford wrote: > I am sure this is a dumb question: I am not only new > to this mail list but a > relatively new ham: > What does "12 is going to die" mean? > Is this a propagation issue or a legal issue? > > thanks, > Tom > > P.S. > Osten - I am new to Ham radio but just from an > Electrical Eng point of view, > IMHO this idea sounds like a nonstarter (for many of > the points you bring > up). Why don't ya learn to like tuners - a matched > system is a happy system > ;) > best of luck 73 > > > ----- Original Message ----- > From: "Osten B Magnusson" > To: > Sent: Sunday, May 04, 2003 5:28 PM > Subject: [Antennas] Questions! > > > > > Friends! > > I was on this list some years ago and now I'm back > again! > A question or two: > > I'm living on an urban lot less than 1000 square > meters, and > no space for more than one tower. I have been using > an > inverted vee for a couple of years on 80 meter CW, > more > than 230 DXCC-''entities'' worked, and now I'm going > to use > it also on 17, 30, 80 CW - 3500 - 3225, 80 SSB 3575 > - 3580 > and 160 meters. My idea is to have relays in each > leg adding > lengths when going from higher to lower frequencies. > In this > case it means 4 relays in each leg, totally 8 > relays. > > As there is high voltage in the ends of the legs > what kind of > light-weight relays can I use, not too expensive and > easy to > get? > > How will the 12 or 24 Volt DC lines to the relays > affect the > antenna? > > I think you may say it's simpler to use an antenna > tuner but > NO, I don't like them... > > Would like to get your answers to the questions and > also > of course your opinion to the whole idea, thanks in > advance. > > By the way, I'm a DX'er but everything worked on 40, > 20 and > 10 meters, 12 is going to die, so no need for those > bands. > I would like to put up a monoband beam for 30 meters > but the > problem is to have that at 70 feet as I need a > support higher > than that to get the beam rotatable inside the > inverted vee, > probably impossible! > > Hope to hear from you, all the best and 73 de > > Osten SM5DQC sm5dqc@algonet.se > > > - - - > > Your moderator for this list is: > Larry Wilson KE1HZ antennas-owner@mailman.qth.net > _______________________________________________ > Antennas mailing list > Antennas@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/antennas > > - - - > > Your moderator for this list is: > Larry Wilson KE1HZ antennas-owner@mailman.qth.net > _______________________________________________ > Antennas mailing list > Antennas@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/antennas __________________________________ Do you Yahoo!? The New Yahoo! Search - Faster. Easier. Bingo. http://search.yahoo.com From bhawes1@juno.com Mon May 5 04:33:28 2003 From: bhawes1@juno.com (William E Hawes) Date: Sun, 4 May 2003 22:33:28 -0500 Subject: [Antennas] Questions! Message-ID: <20030504.223329.2336.2.bhawes1@juno.com> Hi All, It is good to have new ideas granted, but old timers in this hobby don't like newcomers to have to "rediscover the wheel". Switching lengths of an antenna by relays is doing it "the hard way". A non-resonant antenna fed with ladder line or open wire feeders is a far more practical solution for a multiband antenna. 73 Bill-W9ERG One of the 3875 Kilowatt Alley group www.KJ9T.com From IamSF5@aol.com Mon May 5 04:48:29 2003 From: IamSF5@aol.com (IamSF5@aol.com) Date: Sun, 4 May 2003 23:48:29 EDT Subject: [Antennas] The 88 foot dipole and a few questions Message-ID: <1ea.80c0910.2be7390d@aol.com> Hi Gang, Some time ago I recall reading on a private site about an 88 foot dipole. I cannot locate the info now and wanted to try this. I did a search and the closest I came to it was the Carolina Windom antenna. ----------------------------------------------------------- If I make this 88 foot dipole must it be fed with ladder line? If so can I run say 40 feet and then terminate it to coax? Any information is greatly appreciated. Thanks Bob AF2Q From k6mhe@mendolink.com Mon May 5 04:56:37 2003 From: k6mhe@mendolink.com (Dan Richardson) Date: Sun, 04 May 2003 20:56:37 -0700 Subject: [Antennas] The 88 foot dipole and a few questions In-Reply-To: <1ea.80c0910.2be7390d@aol.com> Message-ID: <5.1.0.14.2.20030504205559.00b3e930@mail.mendolink.com> Here you go: http://www.cebik.com/aledz.html Danny At 11:48 PM 5/4/2003 -0400, you wrote: >Hi Gang, >Some time ago I recall reading on a private site about an 88 foot dipole. >I cannot locate the info now and wanted to try this. >I did a search and the closest I came to it was the Carolina Windom antenna. >----------------------------------------------------------- >If I make this 88 foot dipole must it be fed with ladder line? >If so can I run say 40 feet and then terminate it to coax? >Any information is greatly appreciated. >Thanks >Bob >AF2Q >- - - > >Your moderator for this list is: >Larry Wilson KE1HZ antennas-owner@mailman.qth.net >_______________________________________________ >Antennas mailing list >Antennas@mailman.qth.net >http://mailman.qth.net/mailman/listinfo/antennas From IamSF5@aol.com Mon May 5 05:14:59 2003 From: IamSF5@aol.com (IamSF5@aol.com) Date: Mon, 5 May 2003 00:14:59 EDT Subject: [Antennas] Re: That was fast Message-ID: <37.3824d219.2be73f43@aol.com> Thanks Danny and Tom for the fast response. Thats what i'm looking for. 73 Bob AF2Q From davidw@copper.net Mon May 5 10:53:46 2003 From: davidw@copper.net (David J. Windisch) Date: Mon, 5 May 2003 05:53:46 -0400 Subject: [Antennas] Questions! References: <000201c31284$2d1c0560$ec287f3e@g1b8u4> <000e01c31292$cedbc3a0$0100a8c0@monster> Message-ID: <004c01c312ec$3a2cc420$c9eaddcf@t6a1s1> Bob, you silver-tongued devil. Give us more of those terms of endearment to our fellow man, and encouragement of experimentation. And, tell us who micturated in your porridge yesterday. Insincerely, N3HE ----- Original Message ----- From: "Robert Lay (W9DMK)" To: "Osten B Magnusson" ; Sent: Sunday, May 04, 2003 7:07 PM Subject: Re: [Antennas] Questions! > Dear Osten, > > It's a totally ridiculous idea > and isn't worth even trying. > As you say, the > voltage is very high (the current is also very low) at the ends of a dipole. > Therefore, there isn't a relay in existence that can help you there. > Did it ever occur to you that if such an idea had any chance at all, someone would > have already tried it and published the results? > In fact, the only antennas that I have ever heard of that use relays, use the relay or > relays for > switching in the transmission line - hopefully, at a point where the current > and voltage are consistent with the capability of the relay. > > There is no good reason for having a dipole be one half wavelength other > than a fascination for a particular radiation pattern. You still put all of > the energry into space - somewhere - unless there is an efficiency issue, in > which case you deal with the efficiency issue - not the length of the > radiator. > > Tuners are not bad - you should get used to that and embrace the idea - it > works for everyone else. > > 73 de W9DMK (Bob Lay in Dahlgren, VA BIGSNIP From sm5dqc@algonet.se Mon May 5 11:42:39 2003 From: sm5dqc@algonet.se (Osten B Magnusson) Date: Mon, 5 May 2003 12:42:39 +0200 Subject: [Antennas] Thanks all of you! References: <000201c31284$2d1c0560$ec287f3e@g1b8u4> <000e01c31292$cedbc3a0$0100a8c0@monster> Message-ID: <000201c312f3$97dcf8e0$e9287f3e@g1b8u4> Good morning friends and thanks for all the answers regarding my question about = relay-switching a dipole. Seems it's an idea that may work, but also it might not as = there are problems involved: Need very BIG relays which means also very heavy antenna wire, also don't know how the relay feedlines will affect the = antenna and whether stray RF will affect the relays... However I may try it = during the long summer coming here soon! Seems most of you think I should use a zepp with ladderline and tuner, but I must get to know how the pattern, horizontal, will be on different bands. No need here to have RF going straight up in the sky, it will also with an inverted vee but not all of = it. I like antennas that have a 50 - 75 ohms feedpoint, and probably the = idea of using separate dipoles with the same feedline will be better - except = I don't think I can have one for 3505 KHz and one for 3795 KHz on that feedline, no space here to put those two a right angles between them. A good antennatuner covering also 160 meters at 1 KW ''key-down'' is around 600 USD + shipping + customs + VAT will be a lot of money. No used ones - would prefer an old Viking Matchbox and I think those = also included 160 - available in this country, we aren't that many as in USA, = hi! Regarding ''12 is going to die'', sorry for that expression, but 12 = meters will fade out soon, and I don't know what you mean by ''like to be number = 13'' Steve? Also, one comment, I am 63 years old, licensed since 1962, on the bands every day since and NOT a ''newcomer'', however even old-timers can get what most of you think is a ''stupid idea''. I will as I said = try and let you know how it worked out in a couple of months.=20 Once again, Thanks for all answers! All the best to you and yours, 73/DX de Osten SM5DQC sm5dqc@algonet.se or sm5dqc@arrl.net ARRL DXCC fieldchecker DXCC Top Honor Roll 99 percent on CW =20 ----- Ursprungligt meddelande -----=20 Fr=E5n: "Robert Lay (W9DMK)" Till: "Osten B Magnusson" ; = Skickat: den 5 maj 2003 01:07 =C4mne: Re: [Antennas] Questions! > Dear Osten, >=20 > It's a totally ridiculous idea and isn't worth even trying. As you = say, the > voltage is very high (the current is also very low) at the ends of a = dipole. > Therefore, there isn't a relay in existence that can help you there. = Did it > ever occur to you that if such an idea had any chance at all, someone = would > have already tried it and published the results? In fact, the only = antennas > that I have ever heard of that use relays, use the relay or relays for > switching in the transmission line - hopefully, at a point where the = current > and voltage are consistent with the capability of the relay. >=20 > There is no good reason for having a dipole be one half wavelength = other > than a fascination for a particular radiation pattern. You still put = all of > the energry into space - somewhere - unless there is an efficiency = issue, in > which case you deal with the efficiency issue - not the length of the > radiator. >=20 > Tuners are not bad - you should get used to that and embrace the idea = - it > works for everyone else. >=20 > 73 de W9DMK (Bob Lay in Dahlgren, VA > http://www.qsl.net/w9dmk > ----- Original Message -----=20 > From: "Osten B Magnusson" > To: > Sent: Sunday, May 04, 2003 5:28 PM > Subject: [Antennas] Questions! >=20 >=20 >=20 >=20 > Friends! >=20 > I was on this list some years ago and now I'm back again! > A question or two: >=20 > I'm living on an urban lot less than 1000 square meters, and > no space for more than one tower. I have been using an > inverted vee for a couple of years on 80 meter CW, more > than 230 DXCC-''entities'' worked, and now I'm going to use > it also on 17, 30, 80 CW - 3500 - 3225, 80 SSB 3575 - 3580 > and 160 meters. My idea is to have relays in each leg adding > lengths when going from higher to lower frequencies. In this > case it means 4 relays in each leg, totally 8 relays. >=20 > As there is high voltage in the ends of the legs what kind of > light-weight relays can I use, not too expensive and easy to > get? >=20 > How will the 12 or 24 Volt DC lines to the relays affect the > antenna? >=20 > I think you may say it's simpler to use an antenna tuner but > NO, I don't like them... >=20 > Would like to get your answers to the questions and also > of course your opinion to the whole idea, thanks in advance. >=20 > By the way, I'm a DX'er but everything worked on 40, 20 and > 10 meters, 12 is going to die, so no need for those bands. > I would like to put up a monoband beam for 30 meters but the > problem is to have that at 70 feet as I need a support higher > than that to get the beam rotatable inside the inverted vee, > probably impossible! >=20 > Hope to hear from you, all the best and 73 de >=20 > Osten SM5DQC sm5dqc@algonet.se >=20 >=20 > - - - >=20 > Your moderator for this list is: > Larry Wilson KE1HZ antennas-owner@mailman.qth.net > _______________________________________________ > Antennas mailing list > Antennas@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/antennas >=20 > - - -=20 >=20 > Your moderator for this list is: > Larry Wilson KE1HZ antennas-owner@mailman.qth.net > _______________________________________________ > Antennas mailing list > Antennas@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/antennas > From sm5dqc@algonet.se Mon May 5 12:21:08 2003 From: sm5dqc@algonet.se (Osten B Magnusson) Date: Mon, 5 May 2003 13:21:08 +0200 Subject: [Antennas] Questions! References: <000201c31284$2d1c0560$ec287f3e@g1b8u4> <000e01c31292$cedbc3a0$0100a8c0@monster> <004c01c312ec$3a2cc420$c9eaddcf@t6a1s1> Message-ID: <000201c312f8$8afe0b00$2a287f3e@g1b8u4> David! I wasn't upset at all by the posting from Bob, W9DMK. Bob knows what he is talking about, and confirmed my fear for the high voltage at the end of a dipole / inv.vee which will make a need for so big relays that the idea is as he said ''totally ridiculous''. I will = however=20 try it just for fun but I'm quite sure Bob is correct and I will later = probably=20 have to confirm this! If there are many postings the way you wrote, David, N3HE, I will leave=20 the reflector again as I did a couple of years ago, that one wasn't = nice! 73 de Osten SM5DQC e-mail: sm5dqc@algonet.se ----- Ursprungligt meddelande -----=20 Fr=E5n: "David J. Windisch" Till: Skickat: den 5 maj 2003 11:53 =C4mne: Re: [Antennas] Questions! > Bob, you silver-tongued devil. Give us more of those terms of = endearment > to our fellow man, and encouragement of experimentation. And, tell = us who > micturated in your porridge yesterday. >=20 > Insincerely, >=20 > N3HE >=20 > ----- Original Message -----=20 > From: "Robert Lay (W9DMK)" > To: "Osten B Magnusson" ; = > Sent: Sunday, May 04, 2003 7:07 PM > Subject: Re: [Antennas] Questions! >=20 >=20 > > Dear Osten, > > > > It's a totally ridiculous idea >=20 _____________________________________SNIP by SM5DQC___________ From bhawes1@juno.com Mon May 5 12:35:20 2003 From: bhawes1@juno.com (William E Hawes) Date: Mon, 5 May 2003 06:35:20 -0500 Subject: [Antennas] Questions! Message-ID: <20030505.063520.2176.0.bhawes1@juno.com> To N3HE, You are the one who ought to watch his tongue! Bob is a seasoned EE Design Engineer and still teaches in a College. His points are well taken for those of us with years of experience with this hobby. 73 de Bill-W9ERG One of the 3875 Kilowatt Alley Gang www.KJ9T.com From baycock@direcway.com Mon May 5 12:23:30 2003 From: baycock@direcway.com (Bill Aycock) Date: Mon, 05 May 2003 06:23:30 -0500 Subject: [Antennas] Questions! In-Reply-To: <004c01c312ec$3a2cc420$c9eaddcf@t6a1s1> References: <000201c31284$2d1c0560$ec287f3e@g1b8u4> <000e01c31292$cedbc3a0$0100a8c0@monster> Message-ID: <5.2.0.9.2.20030505060222.031c1e30@pop3.direcway.com> David- don't jump on Bob- he is right. One of the reasons these reflectors exist is to spread the word, as needed, from those who know to those who don't. When a proposed experiment only duplicates a situation that can be described by reference to earlier work, negative comment just saves effort. Otherwise, why ask? The problem is finding the people who already know; that's what this forum is for If the EH people had listened, lots of effort and hot air would have been saved. . Bill At 05:53 AM 5/5/2003 -0400, you wrote: >Bob, you silver-tongued devil. Give us more of those terms of endearment >to our fellow man, and encouragement of experimentation. And, tell us who >micturated in your porridge yesterday. > >Insincerely, > >N3HE > >----- Original Message ----- >From: "Robert Lay (W9DMK)" >To: "Osten B Magnusson" ; >Sent: Sunday, May 04, 2003 7:07 PM >Subject: Re: [Antennas] Questions! > > > > Dear Osten, > > > > It's a totally ridiculous idea > > > and isn't worth even trying. > > > As you say, the > > voltage is very high (the current is also very low) at the ends of a >dipole. > > > Therefore, there isn't a relay in existence that can help you there. > > > Did it ever occur to you that if such an idea had any chance at all, >someone would > > have already tried it and published the results? > > > In fact, the only antennas that I have ever heard of that use relays, use >the relay or > > > relays for > > switching in the transmission line - hopefully, at a point where the >current > > and voltage are consistent with the capability of the relay. > > > > There is no good reason for having a dipole be one half wavelength other > > than a fascination for a particular radiation pattern. You still put all >of > > the energry into space - somewhere - unless there is an efficiency issue, >in > > which case you deal with the efficiency issue - not the length of the > > radiator. > > > > Tuners are not bad - you should get used to that and embrace the idea - it > > works for everyone else. > > > > 73 de W9DMK (Bob Lay in Dahlgren, VA >BIGSNIP > >- - - > >Your moderator for this list is: >Larry Wilson KE1HZ antennas-owner@mailman.qth.net >_______________________________________________ >Antennas mailing list >Antennas@mailman.qth.net >http://mailman.qth.net/mailman/listinfo/antennas Bill Aycock - W4BSG Woodville, Alabama --- StripMime Report -- processed MIME parts --- multipart/alternative text/plain (text body -- kept) text/html The reason this message is shown is because the post was in HTML or had an attachment. Attachments are not allowed. To learn how to post in Plain-Text go to: http://www.expita.com/nomime.html --- From DELSONCOMM@aol.com Mon May 5 13:16:02 2003 From: DELSONCOMM@aol.com (DELSONCOMM@aol.com) Date: Mon, 5 May 2003 08:16:02 EDT Subject: [Antennas] mosley cl33 Message-ID: <15e.1f592047.2be7b002@aol.com> hello and thank who ever send me some information but can some one send me the diagram of the 40m trap i have spear trap from my old cl 33 so any info on the 40m trap how many turn and so on long of each element and more , many thanks for the help 4Z4KA Ody --- StripMime Report -- processed MIME parts --- multipart/alternative text/plain (text body -- kept) text/html The reason this message is shown is because the post was in HTML or had an attachment. Attachments are not allowed. To learn how to post in Plain-Text go to: http://www.expita.com/nomime.html --- From dufferjames@hotmail.com Mon May 5 14:01:03 2003 From: dufferjames@hotmail.com (James Duffer) Date: Mon, 05 May 2003 08:01:03 -0500 Subject: [Antennas] Questions! Message-ID: snip >Dear Osten, > >It's a totally ridiculous idea and isn't worth even trying. As you say, the >voltage is very high (the current is also very low) at the ends of a >dipole. >Therefore, there isn't a relay in existence that can help you there. Did it >ever occur to you that if such an idea had any chance at all, someone would >have already tried it and published the results? 73 de W9DMK (Bob Lay in >Dahlgren, VA snip Think about it. This kind of thinking doesn't behoove experimentation...just maybe the same attitude existed all along...and it actually hasn't been tried. I also think it won't work and that the use of traps would be better....but, I haven't tried, and I don't know for a fact it won't work, I haven't seen it tried before, and I haven't read where it was tried and didn't work either. Go for it and let us know what happened! 73, wd4air _________________________________________________________________ Add photos to your e-mail with MSN 8. Get 2 months FREE*. http://join.msn.com/?page=features/featuredemail From n4sl@yahoo.com Mon May 5 14:21:56 2003 From: n4sl@yahoo.com (Steve L.) Date: Mon, 5 May 2003 06:21:56 -0700 (PDT) Subject: [Antennas] Questions! In-Reply-To: Message-ID: <20030505132156.34460.qmail@web40812.mail.yahoo.com> Regarding ''12 is going to die'', sorry for that expression, but 12 meters will fade out soon, and I don't know what you mean by ''like to be number 13'' Steve? Oh, it's a dumb joke -- if '12 are going to die' (as in 12 people will die), then I'd like to be the 13th so I don't die. __________________________________ Do you Yahoo!? The New Yahoo! Search - Faster. Easier. Bingo. http://search.yahoo.com From dkelley@bucknell.edu Mon May 5 16:12:33 2003 From: dkelley@bucknell.edu (David Kelley) Date: Mon, 05 May 2003 11:12:33 -0400 Subject: [Antennas] Questions! In-Reply-To: <20030505080115.81737328AA6@mailman.qth.net> Message-ID: <5.1.1.5.2.20030505105502.00a8ac80@mail.bucknell.edu> Osten, I'm not sure why you received so many mildly hostile replies to your question, but I'll try to help if I can. As some responders have pointed out, you may have trouble with high voltage at the locations of the relays. This is likely to happen if you use smaller relays. However, many hams have successfully used shorting wires to change the length of their antennas. Cut the antenna wire at the terminating length for the higher band and insert a "dogbone" insulator at that point. Solder a short wire to one of the antenna wire ends, and attach an alligator clip to the other end of the short wire. Clip the short wire to the other antenna wire to make the overall antenna length longer, and unclip it to make it shorter. This solution is an improvement over the relay approach because the separation between conductors with the wire unclipped is large enough to prevent arcing. The main disadvantages of this system are obvious: It requires lowering the antenna to clip/unclip the wires, and corrosion may prevent good electrical contact over time. However, you might be able to devise solutions to these problems. But a better solution might be simply to use traps in the antenna. Contrary to popular belief, the amount of loss encountered in a well-designed trap is insignificant (a few dB at most). In my opinion, the convenience gained by using traps far outweighs the small amount of loss. One could argue that the popular random-length dipole/matching network combination leads to just as much loss (if not more) than using traps. >I'm living on an urban lot less than 1000 square meters, and >no space for more than one tower. I have been using an=20 >inverted vee for a couple of years on 80 meter CW, more >than 230 DXCC-''entities'' worked, and now I'm going to use >it also on 17, 30, 80 CW - 3500 - 3225, 80 SSB 3575 - 3580 >and 160 meters. My idea is to have relays in each leg adding >lengths when going from higher to lower frequencies. In this >case it means 4 relays in each leg, totally 8 relays. > >As there is high voltage in the ends of the legs what kind of >light-weight relays can I use, not too expensive and easy to >get? > >How will the 12 or 24 Volt DC lines to the relays affect the >antenna? Some of the RF energy is likely to couple into the DC lines. Whether or not this is a problem depends on many factors, including the lengths of the DC lines and their physical orientation relative to the antenna. If you end up using this approach, you should use decoupling capacitors and RF chokes where the DC lines enter the control box at your operating position. 73, Dave NB4J -- David F. Kelley, Ph.D. Assistant Professor Electrical Engineering Dept. Bucknell University Lewisburg, PA 17837 (570) 577-1313 dkelley@bucknell.edu From les99a@rconnect.com Mon May 5 16:52:17 2003 From: les99a@rconnect.com (Les Severson) Date: Mon, 05 May 2003 10:52:17 -0500 Subject: [Antennas] Questions! References: <20030504.223329.2336.2.bhawes1@juno.com> Message-ID: <3EB688B1.9050108@rconnect.com> AMEN to Bills suggestion ! Get use to a good balanced line tuner and buy some ladder line.. hi You'll save yourself a lot of grief. 73, Les, W�OJH ------------------------------------------------------- William E Hawes wrote: > Hi All, > > It is good to have new ideas granted, but old timers in this > hobby don't like newcomers to have to "rediscover the wheel". Switching > lengths of an antenna by relays is doing it "the hard way". A > non-resonant antenna fed with ladder line or open wire feeders is a far > more practical solution for a multiband antenna. > > 73 Bill-W9ERG One of the 3875 Kilowatt Alley group > www.KJ9T.com > - - - > > Your moderator for this list is: > Larry Wilson KE1HZ antennas-owner@mailman.qth.net > _______________________________________________ > Antennas mailing list > Antennas@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/antennas > From w9dmk@crosslink.net Mon May 5 17:25:43 2003 From: w9dmk@crosslink.net (Robert Lay (W9DMK)) Date: Mon, 5 May 2003 12:25:43 -0400 Subject: [Antennas] Questions! References: <000201c31284$2d1c0560$ec287f3e@g1b8u4> <000e01c31292$cedbc3a0$0100a8c0@monster> <004c01c312ec$3a2cc420$c9eaddcf@t6a1s1> <000201c312f8$8afe0b00$2a287f3e@g1b8u4> Message-ID: <004a01c31322$fad9f630$0100a8c0@monster> ...snip No need here to have RF going straight up in the sky, it will also with an inverted vee but not all of it. Dear Osten, The vertical pattern (how much goes up in the sky) will be primarily a question of height above ground. With a low antenna, it will be a cloud-warmer. The horizontal pattern is most affected by antenna length and begins to have many lobes when the antenna becomes multiples of half wavelength. With a single Herzian antenna (center fed, horizontal), you can work any band you like with an open wire or ladder-line feed. Just consider that the impedance matching device does not have to be expensive. At each frequency of operation, or narrow band of operation, there will be a specific input impedance looking into the feedline from the transmitter. The challenge is to transform that impedance into 50 + j 0 ohms. If you are intending to operate on 8 different bands, then you might build 8 different impedance transformation networks, each in its own box, using off-the-shelf components. They do not have to be expensive variable capacitors and rotary inductors. Consider this - an additional length of balanced feedline is either an inductance or a capacitance, depending upon its length. Also, an inductor, hand wound on a 5 - 10 cm diameter plastic pipe is just as effective as an expensive commercial model. If you have the room and are willing to hang different lengths of feedline just outside the shack, you can do some miraculous impedance transformations just by switching in different lengths of series transformation lines or parallel stubs - either with relays or using the General Radio style banana plugs. The real challenge is learning your way around the Smith Chart, which is not nearly so difficult as most people think. If you can borrow an impedance bridge (e.g. the MFJ Antenna Analyzer) for a few months from a friend, by the end of summer you will have 8 impedance transforming boxes all built and ready to plug in between the transmitter and the feed line. Try the free Smith Chart program at my Web site. 73 de W9DMK (Bob Lay in Dahlgren, VA http://www.qsl.net/w9dmk From Rick Cole VK3YM" <000e01c31292$cedbc3a0$0100a8c0@monster> <000201c312f3$97dcf8e0$e9287f3e@g1b8u4> Message-ID: <014a01c31328$e962ed20$1dd932d2@house> Osten I read ur email with curiosity as to ur not having any s/h antenna tuners available to you... is ur requirement for 1kW power only and also what antennas are you most likely to run...ie Balanced or unbalanced or both.. The reason i am asking is that i would like to help you out with a tuner...by way of the neccessary parts less case... If you are able to manufacture the case I will post to you FREE OF CHARGE the components to build one.. If you can manufacture the case it would be much cheaper to post you the parts rather than a built unit... Let me know your address so i can get the parts off to you... have fun with radio Rick ----- Original Message ----- From: "Osten B Magnusson" To: Sent: Monday, May 05, 2003 8:42 PM Subject: [Antennas] Thanks all of you! Good morning friends and thanks for all the answers regarding my question about relay-switching a dipole. Seems it's an idea that may work, but also it might not as there are problems involved: Need very BIG relays which means also very heavy antenna wire, also don't know how the relay feedlines will affect the antenna and whether stray RF will affect the relays... However I may try it during the long summer coming here soon! Seems most of you think I should use a zepp with ladderline and tuner, but I must get to know how the pattern, horizontal, will be on different bands. No need here to have RF going straight up in the sky, it will also with an inverted vee but not all of it. I like antennas that have a 50 - 75 ohms feedpoint, and probably the idea of using separate dipoles with the same feedline will be better - except I don't think I can have one for 3505 KHz and one for 3795 KHz on that feedline, no space here to put those two a right angles between them. A good antennatuner covering also 160 meters at 1 KW ''key-down'' is around 600 USD + shipping + customs + VAT will be a lot of money. No used ones - would prefer an old Viking Matchbox and I think those also included 160 - available in this country, we aren't that many as in USA, hi! Regarding ''12 is going to die'', sorry for that expression, but 12 meters will fade out soon, and I don't know what you mean by ''like to be number 13'' Steve? Also, one comment, I am 63 years old, licensed since 1962, on the bands every day since and NOT a ''newcomer'', however even old-timers can get what most of you think is a ''stupid idea''. I will as I said try and let you know how it worked out in a couple of months. Once again, Thanks for all answers! All the best to you and yours, 73/DX de Osten SM5DQC sm5dqc@algonet.se or sm5dqc@arrl.net ARRL DXCC fieldchecker DXCC Top Honor Roll 99 percent on CW ----- Ursprungligt meddelande ----- Fr�n: "Robert Lay (W9DMK)" Till: "Osten B Magnusson" ; Skickat: den 5 maj 2003 01:07 �mne: Re: [Antennas] Questions! > Dear Osten, > > It's a totally ridiculous idea and isn't worth even trying. As you say, the > voltage is very high (the current is also very low) at the ends of a dipole. > Therefore, there isn't a relay in existence that can help you there. Did it > ever occur to you that if such an idea had any chance at all, someone would > have already tried it and published the results? In fact, the only antennas > that I have ever heard of that use relays, use the relay or relays for > switching in the transmission line - hopefully, at a point where the current > and voltage are consistent with the capability of the relay. > > There is no good reason for having a dipole be one half wavelength other > than a fascination for a particular radiation pattern. You still put all of > the energry into space - somewhere - unless there is an efficiency issue, in > which case you deal with the efficiency issue - not the length of the > radiator. > > Tuners are not bad - you should get used to that and embrace the idea - it > works for everyone else. > > 73 de W9DMK (Bob Lay in Dahlgren, VA > http://www.qsl.net/w9dmk > ----- Original Message ----- > From: "Osten B Magnusson" > To: > Sent: Sunday, May 04, 2003 5:28 PM > Subject: [Antennas] Questions! > > > > > Friends! > > I was on this list some years ago and now I'm back again! > A question or two: > > I'm living on an urban lot less than 1000 square meters, and > no space for more than one tower. I have been using an > inverted vee for a couple of years on 80 meter CW, more > than 230 DXCC-''entities'' worked, and now I'm going to use > it also on 17, 30, 80 CW - 3500 - 3225, 80 SSB 3575 - 3580 > and 160 meters. My idea is to have relays in each leg adding > lengths when going from higher to lower frequencies. In this > case it means 4 relays in each leg, totally 8 relays. > > As there is high voltage in the ends of the legs what kind of > light-weight relays can I use, not too expensive and easy to > get? > > How will the 12 or 24 Volt DC lines to the relays affect the > antenna? > > I think you may say it's simpler to use an antenna tuner but > NO, I don't like them... > > Would like to get your answers to the questions and also > of course your opinion to the whole idea, thanks in advance. > > By the way, I'm a DX'er but everything worked on 40, 20 and > 10 meters, 12 is going to die, so no need for those bands. > I would like to put up a monoband beam for 30 meters but the > problem is to have that at 70 feet as I need a support higher > than that to get the beam rotatable inside the inverted vee, > probably impossible! > > Hope to hear from you, all the best and 73 de > > Osten SM5DQC sm5dqc@algonet.se > > > - - - > > Your moderator for this list is: > Larry Wilson KE1HZ antennas-owner@mailman.qth.net > _______________________________________________ > Antennas mailing list > Antennas@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/antennas > > - - - > > Your moderator for this list is: > Larry Wilson KE1HZ antennas-owner@mailman.qth.net > _______________________________________________ > Antennas mailing list > Antennas@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/antennas > - - - Your moderator for this list is: Larry Wilson KE1HZ antennas-owner@mailman.qth.net _______________________________________________ Antennas mailing list Antennas@mailman.qth.net http://mailman.qth.net/mailman/listinfo/antennas From sm5dqc@algonet.se Mon May 5 19:35:21 2003 From: sm5dqc@algonet.se (Osten B Magnusson) Date: Mon, 5 May 2003 20:35:21 +0200 Subject: [Antennas] Thanks all of you! References: <000201c31284$2d1c0560$ec287f3e@g1b8u4> <000e01c31292$cedbc3a0$0100a8c0@monster> <000201c312f3$97dcf8e0$e9287f3e@g1b8u4> <014a01c31328$e962ed20$1dd932d2@house> Message-ID: <000b01c31335$17c840a0$95287f3e@g1b8u4> Hello Rick! What unexpected kindness, I will send you an e-mail tomorrow, just have = to do other things right now.=20 Thanks Rick and all the best to you and yours, 73/DX de Osten SM5DQC ----- Ursprungligt meddelande -----=20 Fr=E5n: "Rick Cole VK3YM" Till: "Osten B Magnusson" ; = Skickat: den 5 maj 2003 18:18 =C4mne: Re: [Antennas] Thanks all of you! > Osten > I read ur email with curiosity as to ur not having any s/h antenna = tuners > available to you... > is ur requirement for 1kW power only and also what antennas are you = most > likely to run...ie Balanced or unbalanced or both.. > The reason i am asking is that i would like to help you out with a > tuner...by way of the neccessary parts less case... > If you are able to manufacture the case I will post to you FREE OF = CHARGE > the components to build one.. > If you can manufacture the case it would be much cheaper to post you = the > parts rather than a built unit... > Let me know your address so i can get the parts off to you... > have fun with radio > Rick > ----- Original Message ----- > From: "Osten B Magnusson" > To: > Sent: Monday, May 05, 2003 8:42 PM > Subject: [Antennas] Thanks all of you! >=20 >=20 >=20 >=20 > Good morning friends >=20 > and thanks for all the answers regarding my question about = relay-switching > a dipole. Seems it's an idea that may work, but also it might not as = there > are problems involved: Need very BIG relays which means also very = heavy > antenna wire, also don't know how the relay feedlines will affect the > antenna > and whether stray RF will affect the relays... However I may try it = during > the > long summer coming here soon! Seems most of you think I should use a > zepp with ladderline and tuner, but I must get to know how the = pattern, > horizontal, will be on different bands. No need here to have RF going > straight up in the sky, it will also with an inverted vee but not all = of it. > I like antennas that have a 50 - 75 ohms feedpoint, and probably the = idea > of using separate dipoles with the same feedline will be better - = except I > don't think I can have one for 3505 KHz and one for 3795 KHz on that > feedline, no space here to put those two a right angles between them. > A good antennatuner covering also 160 meters at 1 KW ''key-down'' is > around 600 USD + shipping + customs + VAT will be a lot of money. > No used ones - would prefer an old Viking Matchbox and I think those = also > included 160 - available in this country, we aren't that many as in = USA, hi! > Regarding ''12 is going to die'', sorry for that expression, but 12 = meters > will > fade out soon, and I don't know what you mean by ''like to be number = 13'' > Steve? Also, one comment, I am 63 years old, licensed since 1962, on = the > bands every day since and NOT a ''newcomer'', however even old-timers > can get what most of you think is a ''stupid idea''. I will as I said = try > and let > you know how it worked out in a couple of months. >=20 > Once again, Thanks for all answers! All the best to you and yours, = 73/DX > de >=20 > Osten SM5DQC sm5dqc@algonet.se or sm5dqc@arrl.net > ARRL DXCC fieldchecker DXCC Top Honor Roll 99 percent on CW >=20 >=20 >=20 >=20 >=20 >=20 >=20 > ----- Ursprungligt meddelande ----- > Fr=E5n: "Robert Lay (W9DMK)" > Till: "Osten B Magnusson" ; = > Skickat: den 5 maj 2003 01:07 > =C4mne: Re: [Antennas] Questions! >=20 >=20 > > Dear Osten, > > > > It's a totally ridiculous idea and isn't worth even trying. As you = say, > the > > voltage is very high (the current is also very low) at the ends of a > dipole. > > Therefore, there isn't a relay in existence that can help you there. = Did > it > > ever occur to you that if such an idea had any chance at all, = someone > would > > have already tried it and published the results? In fact, the only > antennas > > that I have ever heard of that use relays, use the relay or relays = for > > switching in the transmission line - hopefully, at a point where the > current > > and voltage are consistent with the capability of the relay. > > > > There is no good reason for having a dipole be one half wavelength = other > > than a fascination for a particular radiation pattern. You still put = all > of > > the energry into space - somewhere - unless there is an efficiency = issue, > in > > which case you deal with the efficiency issue - not the length of = the > > radiator. > > > > Tuners are not bad - you should get used to that and embrace the = idea - it > > works for everyone else. > > > > 73 de W9DMK (Bob Lay in Dahlgren, VA > > http://www.qsl.net/w9dmk > > ----- Original Message ----- > > From: "Osten B Magnusson" > > To: > > Sent: Sunday, May 04, 2003 5:28 PM > > Subject: [Antennas] Questions! > > > > > > > > > > Friends! > > > > I was on this list some years ago and now I'm back again! > > A question or two: > > > > I'm living on an urban lot less than 1000 square meters, and > > no space for more than one tower. I have been using an > > inverted vee for a couple of years on 80 meter CW, more > > than 230 DXCC-''entities'' worked, and now I'm going to use > > it also on 17, 30, 80 CW - 3500 - 3225, 80 SSB 3575 - 3580 > > and 160 meters. My idea is to have relays in each leg adding > > lengths when going from higher to lower frequencies. In this > > case it means 4 relays in each leg, totally 8 relays. > > > > As there is high voltage in the ends of the legs what kind of > > light-weight relays can I use, not too expensive and easy to > > get? > > > > How will the 12 or 24 Volt DC lines to the relays affect the > > antenna? > > > > I think you may say it's simpler to use an antenna tuner but > > NO, I don't like them... > > > > Would like to get your answers to the questions and also > > of course your opinion to the whole idea, thanks in advance. > > > > By the way, I'm a DX'er but everything worked on 40, 20 and > > 10 meters, 12 is going to die, so no need for those bands. > > I would like to put up a monoband beam for 30 meters but the > > problem is to have that at 70 feet as I need a support higher > > than that to get the beam rotatable inside the inverted vee, > > probably impossible! > > > > Hope to hear from you, all the best and 73 de > > > > Osten SM5DQC sm5dqc@algonet.se > > > > > > - - - > > > > Your moderator for this list is: > > Larry Wilson KE1HZ antennas-owner@mailman.qth.net > > _______________________________________________ > > Antennas mailing list > > Antennas@mailman.qth.net > > http://mailman.qth.net/mailman/listinfo/antennas > > > > - - - > > > > Your moderator for this list is: > > Larry Wilson KE1HZ antennas-owner@mailman.qth.net > > _______________________________________________ > > Antennas mailing list > > Antennas@mailman.qth.net > > http://mailman.qth.net/mailman/listinfo/antennas > > > - - - >=20 > Your moderator for this list is: > Larry Wilson KE1HZ antennas-owner@mailman.qth.net > _______________________________________________ > Antennas mailing list > Antennas@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/antennas >=20 >=20 > - - -=20 >=20 > Your moderator for this list is: > Larry Wilson KE1HZ antennas-owner@mailman.qth.net > _______________________________________________ > Antennas mailing list > Antennas@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/antennas > From IamSF5@aol.com Mon May 5 19:36:48 2003 From: IamSF5@aol.com (IamSF5@aol.com) Date: Mon, 5 May 2003 14:36:48 EDT Subject: [Antennas] The 88 foot dipole and a few questions/Many Thanks to all Message-ID: <73.3088ebd7.2be80940@aol.com> Hi Gang, Thanks to all who responded. Also a big thanks to Harvet W4TG who took the time and sent me three letters. I now will be able to run a dipole fed with ladder line and use coax as feeders to bring it into the shack. Again, Thanks for all the info. AF2Q From ac5p@juno.com Mon May 5 22:19:19 2003 From: ac5p@juno.com (Mike J Maloney) Date: Mon, 5 May 2003 16:19:19 -0500 Subject: [Antennas] Questions! Message-ID: <20030505.161921.-1045871.0.ac5p@juno.com> You may want to take a look at this idea as an alternative. It works. www.qsl.net/w5dxp/notuner.htm 73, Mike, ac5p From ve7hcb@rac.ca Tue May 6 00:07:12 2003 From: ve7hcb@rac.ca (Chris BONDE) Date: Mon, 05 May 2003 16:07:12 -0700 Subject: [Antennas] Questions! In-Reply-To: <20030505.063520.2176.0.bhawes1@juno.com> Message-ID: <4.3.1.1.20030505160105.00a95750@mail.netidea.com> I think that this has gone on enough, however, what Bob said (if I remember correctly) was not in line with what I would expect from a good instructor at college. Just state that in all probability the scheme would not work, give the reasons why. Not call it what he did. Note the answer by Dave NB4J Chris opr VE7HCB At 06:35 AM 2003-05-05 -0500, you wrote: >To N3HE, > > You are the one who ought to watch his tongue! Bob is a seasoned >EE Design Engineer and still teaches in a College. His points are well >taken for those of us with years of experience with this hobby. > >73 de Bill-W9ERG One of the 3875 Kilowatt Alley Gang >www.KJ9T.com From ve7hcb@rac.ca Tue May 6 00:14:46 2003 From: ve7hcb@rac.ca (Chris BONDE) Date: Mon, 05 May 2003 16:14:46 -0700 Subject: [Antennas] The 88 foot dipole and a few questions/Many Thanks to all In-Reply-To: <73.3088ebd7.2be80940@aol.com> Message-ID: <4.3.1.1.20030505161210.00aa3bf0@mail.netidea.com> I like this idea. Now can you let me in on it. 88ft top, either flat or V, what length and impedance ladder line, and what coax and how do you connect the coax? Is it 2 pieces of coax making the line still balanced to a tuner, or, is it a 4:1 balun throught coax to the tuner? Chris opr VE7HCB At 02:36 PM 2003-05-05 -0400, you wrote: >Hi Gang, >Thanks to all who responded. >Also a big thanks to Harvet W4TG who took the time and sent me three letters. >I now will be able to run a dipole fed with ladder line and use coax as >feeders to bring it into the shack. >Again, >Thanks for all the info. >AF2Q From IamSF5@aol.com Tue May 6 06:26:37 2003 From: IamSF5@aol.com (IamSF5@aol.com) Date: Tue, 6 May 2003 01:26:37 EDT Subject: [Antennas] The 88 foot dipole and a few questions/Many Thanks to all Message-ID: <1da.914f381.2be8a18d@aol.com> In a message dated 5/5/03 10:05:39 PM Pacific Daylight Time, ve7hcb@rac.ca writes: You have the wrong person on this. All the credit goes to W4TG. He sent me the info,I printed everything and just about an hour ago I deleted the mail. I run an older version of AOL and can't retrieve deleted mail. The antenna is designed for low profile and works very well.. I can't remember if he CC'ed it to the list but you may want to check. Sorry Bob AF2Q << >Hi Gang, >Thanks to all who responded. >Also a big thanks to Harvet W4TG who took the time and sent me three letters. >I now will be able to run a dipole fed with ladder line and use coax as >feeders to bring it into the shack. >Again, >Thanks for all the info. >AF2Q >> From W6jod@aol.com Tue May 6 15:04:43 2003 From: W6jod@aol.com (W6jod@aol.com) Date: Tue, 6 May 2003 10:04:43 EDT Subject: [Antennas] Thanks all of you! Message-ID: <21.2ed2f454.2be91afb@aol.com> Hello Osten, I've been following this thread with interest. The one idea not mentioned that you might consider is using traps rather than relays to change bands. The traps would in a sense be automatic switches (or relays) in that they would change the antenna length as you change bands. I personally would chose the multiple dipole method mentioned earlier. I'm currently operating portable from the Ozarks in Southwest Missouri and put up an antenna on this past Saturday. It is a 40 meter and 20 meter dipole hooked to the same feedline and about 45 or 50 feet in the air. I tuned it with an antenna analyzer while a few feet off the ground. After erecting it, the 40 meter dipole was right on at around 7.15 MHz but the 20 meter dipole changed from 14.2 MHz to 14.6 MHz and the 2:1 SWR limit was 14.35 MHz or so. My antenna tuner nicely brought that down to 1:1 across the band. The antenna is working great! I've heard all sorts of DX and have made a few contacts as time permits. Good luck on your project. 73, Norm Hall, W6JOD --- StripMime Report -- processed MIME parts --- multipart/alternative text/plain (text body -- kept) text/html The reason this message is shown is because the post was in HTML or had an attachment. Attachments are not allowed. To learn how to post in Plain-Text go to: http://www.expita.com/nomime.html --- From ea5xq@qsl.net Tue May 6 15:06:30 2003 From: ea5xq@qsl.net (Juan A. Bertolin (EA5XQ)) Date: Tue, 06 May 2003 17:06:30 +0300 Subject: [Antennas] Hairpin Monopole Message-ID: <5.2.0.9.0.20030506164747.00b8b588@mail.cajarural.com> Hi to all, Recently, looking into Internet for information about indoor antennas and=20 antennas for reduced spaces I found the Hairpin Monopole article written by= =20 Wilfred Caron. It seems very interesting antenna, is there other places=20 where I could find more information about this monopole?(I do not see clear= =20 the pictures and explanation of Mr. Caron) Any experience of some of you=20 with this antenna? I'm interested in using it for 20,40 and 80m... Tks es 73 Juan, EA5XQ =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D EA5XQ, QRA:Juan, QTH:Almazora, LOC:IM99XW MEMBER OF/MIEMBRO DE: URE (www.ure.es) y/and SLUREVILL (Secci=F3n Local URE= =20 Villarreal - http://slurevill.iespana.es/slurevill) CLUBS: G-QRP #9805, QRP-L #1461, EA-QRP #471, EACW #309 E-MAIL: ea5xq@qsl.net MSMESSENGER: ea5xq_Juan@hotmail.com @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ WEB SITE: http://www.qsl.net/ea5xq (english version in http://www.qsl.net/ea5xq/index_eng.html ) =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=20 From royanjoy@ncn.net Tue May 6 16:58:26 2003 From: royanjoy@ncn.net (Roy Koeppe) Date: Tue, 6 May 2003 10:58:26 -0500 Subject: [Antennas] Re: Hairpin monopole Message-ID: <001001c313e8$55491860$362448ce@ncn.net> Concerning, "Hi to all, Recently, looking into Internet for information about indoor antennas and antennas for reduced spaces I found the Hairpin Monopole article written by Wilfred Caron. It seems very interesting antenna, is there other places where I could find more information about this monopole?(I do not see clear the pictures and explanation of Mr. Caron) Any experience of some of you with this antenna? I'm interested in using it for 20,40 and 80m... Tks es 73 Juan, EA5XQ" Hi Juan, The very reasonably priced paperback VERTICAL ANTENNA HANDBOOK by Capt. Paul Lee, N6PL discusses many versions of this antenna. I am using a folded fan vertical unipole myself with very good results. One feature of having a folded element is that the entire antenna is always at direct earth DC ground--a comfort during lightning storms. The book is available from Radio Bookstore at: http:www.radio-ware.com Good luck & 73, Roy K6XK royanjoy@ncn.net From ac7nj@bentonrea.com Tue May 6 17:36:11 2003 From: ac7nj@bentonrea.com (ac7nj@bentonrea.com) Date: Tue, 6 May 2003 16:36:11 -0000 Subject: [Antennas] Receiving Loop help? Message-ID: The receiving loop I found in the antenna book the following receiving loop for the top band and I would like to scale it down to 4.0035 Mhz The original specs: 1.81 Mhz; 20 feet =3D 0.037=EB; the conductor was RG-59 with 21 pF per foot for a total capacitance of 420 pF; 100 pF was added to resonate the loop at 1.810 Mhz. Is this correct: 983.6/4.0035 =3D 245.6805 * 0.037=EB =3D 9.0903457 or 9 foot electrical length ? Or physical length? And has anyone used the MFJ 259 with the MFJ 66 dip meter attachment? I have it but never used it yet. Write soon, Randy AC7NJ =20 =20 From w9dmk@crosslink.net Tue May 6 18:09:39 2003 From: w9dmk@crosslink.net (Robert Lay (W9DMK)) Date: Tue, 6 May 2003 13:09:39 -0400 Subject: [Antennas] Hairpin Monopole References: <5.2.0.9.0.20030506164747.00b8b588@mail.cajarural.com> Message-ID: <000b01c313f2$c696c990$30a4c7cf@monster> ----- Original Message ----- From: "Juan A. Bertolin (EA5XQ)" To: Sent: Tuesday, May 06, 2003 10:06 AM Subject: [Antennas] Hairpin Monopole Hi to all, Recently, looking into Internet for information about indoor antennas and antennas for reduced spaces I found the Hairpin Monopole article written by Wilfred Caron. It seems very interesting antenna, is there other places where I could find more information about this monopole?(I do not see clear the pictures and explanation of Mr. Caron) Any experience of some of you with this antenna? I'm interested in using it for 20,40 and 80m... _______________________________________________________________ Dear Juan, I have built a full size 40 meter version of the quarter wave folded vertical. I used a 35 ft. length of ladder line as the radiating element and suspended it from a tree. It gave a high real (resistive) component to the feed point impedance, as one would expect, and was easy to tune with a standard C-L-C tuner at its base. So far as performance is concerned, it has a low take-off angle by virtue of its intrinsic characteristics and a high efficiency without an extensive ground plane. I used the chain link fence around the yard as my earth connection. My only complaint about this type of antenna for amateur work is the same complaint that I have about all verticals in comparison with Herzian antennas - they just don't measure up in simple A/B switch tests in real QSO's . You may be interested to know that Mr. Caron was the author of the ARRL book, "Antenna Impedance Matching". I used his book in preparing the extensive Help file for my Smith Chart program, which can be found at my Web site. The help file is based almost entirely on Mr. Caron's book. I would not recommend this type of antenna for multi-band use unless you have a remotely controlled tuner at the base of the antenna or are not concerned about the high SWR values that would be encountered on the feed line. 73 de W9DMK (Bob Lay in Dahlgren, VA http://www.qsl.net/w9dmk From w0jrm@arrl.net Wed May 7 02:07:38 2003 From: w0jrm@arrl.net (Rob Matherly) Date: 06 May 2003 20:07:38 -0500 Subject: [Antennas] WTD: Wattmeter / SWR Meter Info Message-ID: <1052269662.1769.39.camel@localhost.localdomain> Hi All; About 5 years ago, I had a hf-vhf wattmeter/SWR meter manufactured by Kenwood. Unfortunately, it bit the dust. This was a neat little meter with a remote head and a lit display. It also had a built-in voltage monitor Does anyone know what the meter I'm speaking of is? I'd like to get another to throw in my truck, and have no idea what the model number was. - Rob From n7ws@yahoo.com Wed May 7 05:47:40 2003 From: n7ws@yahoo.com (Wes Stewart) Date: Tue, 6 May 2003 21:47:40 -0700 (PDT) Subject: [Antennas] Hairpin Monopole In-Reply-To: <000b01c313f2$c696c990$30a4c7cf@monster> Message-ID: <20030507044740.13995.qmail@web20910.mail.yahoo.com> --- "Robert Lay (W9DMK)" wrote: > ----- Original Message ----- > From: "Juan A. Bertolin (EA5XQ)" > To: > Sent: Tuesday, May 06, 2003 10:06 AM > Subject: [Antennas] Hairpin Monopole > > > Hi to all, > > Recently, looking into Internet for information > about indoor antennas and > antennas for reduced spaces I found the Hairpin > Monopole article written by > Wilfred Caron. It seems very interesting antenna, is > there other places > where I could find more information about this > monopole?(I do not see clear > the pictures and explanation of Mr. Caron) Any > experience of some of you > with this antenna? > > I'm interested in using it for 20,40 and 80m... > _______________________________________________________________ > Dear Juan, > > I have built a full size 40 meter version of the > quarter wave folded > vertical. I used a 35 ft. length of ladder line as > the radiating element and > suspended it from a tree. It gave a high real > (resistive) component to the > feed point impedance, as one would expect, and was > easy to tune with a > standard C-L-C tuner at its base. So far as > performance is concerned, it has > a low take-off angle by virtue of its intrinsic > characteristics and a high > efficiency without an extensive ground plane. I used > the chain link fence > around the yard as my earth connection. My only > complaint about this type of > antenna for amateur work is the same complaint that > I have about all > verticals in comparison with Herzian antennas - they > just don't measure up > in simple A/B switch tests in real QSO's > . > You may be interested to know that Mr. Caron was the > author of the ARRL > book, "Antenna Impedance Matching". I used his book > in preparing the > extensive Help file for my Smith Chart program, > which can be found at my Web > site. The help file is based almost entirely on Mr. > Caron's book. > > I would not recommend this type of antenna for > multi-band use unless you > have a remotely controlled tuner at the base of the > antenna or are not > concerned about the high SWR values that would be > encountered on the feed > line. > > 73 de W9DMK (Bob Lay in Dahlgren, VA > http://www.qsl.net/w9dmk > > - - - > > Your moderator for this list is: > Larry Wilson KE1HZ antennas-owner@mailman.qth.net > _______________________________________________ > Antennas mailing list > Antennas@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/antennas __________________________________ Do you Yahoo!? The New Yahoo! Search - Faster. Easier. Bingo. http://search.yahoo.com From n7ws@yahoo.com Wed May 7 05:51:59 2003 From: n7ws@yahoo.com (Wes Stewart) Date: Tue, 6 May 2003 21:51:59 -0700 (PDT) Subject: [Antennas] Hairpin Monopole In-Reply-To: <000b01c313f2$c696c990$30a4c7cf@monster> Message-ID: <20030507045159.14271.qmail@web20910.mail.yahoo.com> --- "Robert Lay (W9DMK)" wrote: [snip] > So far as > performance is concerned, it has > a low take-off angle by virtue of its intrinsic > characteristics and a high > efficiency without an extensive ground plane. Why do you think this antenna has any greater efficiency without a good ground plane than a regular monopole? __________________________________ Do you Yahoo!? The New Yahoo! Search - Faster. Easier. Bingo. http://search.yahoo.com From iam@pmug.org Wed May 7 05:55:51 2003 From: iam@pmug.org (DavidE Benedict) Date: Tue, 06 May 2003 21:55:51 -0700 Subject: [Antennas] WTD: Wattmeter / SWR Meter Info Message-ID: I'd check the kenwood area at arrl.net and QRZ.com David Benedict w7dbh Beaverton, Oregon w0jrm@arrl.net,Internet writes: >Hi All; > >About 5 years ago, I had a hf-vhf wattmeter/SWR meter manufactured by >Kenwood. Unfortunately, it bit the dust. This was a neat little meter >with a remote head and a lit display. It also had a built-in voltage >monitor > >Does anyone know what the meter I'm speaking of is? I'd like to get >another to throw in my truck, and have no idea what the model number >was. > >- Rob > >- - - > >Your moderator for this list is: >Larry Wilson KE1HZ antennas-owner@mailman.qth.net >_______________________________________________ >Antennas mailing list >Antennas@mailman.qth.net >http://mailman.qth.net/mailman/listinfo/antennas > From w9dmk@crosslink.net Wed May 7 13:27:04 2003 From: w9dmk@crosslink.net (Robert Lay (W9DMK)) Date: Wed, 7 May 2003 08:27:04 -0400 Subject: [Antennas] Hairpin Monopole References: <20030507045159.14271.qmail@web20910.mail.yahoo.com> Message-ID: <001901c31494$7ab7d850$0100a8c0@monster> Dear Wes, It's not a matter of what I think - it's a simple fact. The resistive component of the antenna's input impedance (the radiation resistance) is generally higher than a conventional, non-folded radiator. Efficiency is governed by the relationship between the radiation resistance and the ground losses component. Therefore, the higher the radiation resistance the higher the efficiency. Remember, the original discussion of theory about these folded monopoles (or folded dipoles, as well) is that they have a higher radiation resistance. 73 de W9DMK (Bob Lay in Dahlgren, VA http://www.qsl.net/w9dmk From royanjoy@ncn.net Wed May 7 14:02:54 2003 From: royanjoy@ncn.net (Roy Koeppe) Date: Wed, 7 May 2003 08:02:54 -0500 Subject: [Antennas] Re: Hairpin monopoles Message-ID: <002301c31498$fa6344a0$552448ce@ncn.net> Oh, oh, regarding, "It's not a matter of what I think - it's a simple fact. The resistive component of the antenna's input impedance (the radiation resistance) is generally higher than a conventional, non-folded radiator." This old hams' tale has persisted throughout the years and now rears its head again? Radiation resistance and input impedance are two entirely separate things. With a folded element the input impedance is simply stepped up by transformer action alone, just as if you installed a transformer at the feedpoint. Radiation resistance, on the other hand, remains constant. Actually, most folded monopoles have a slightly LOWER radiation resistance than their single conductor counterparts. This obeys the law about "the thinner the conductor, the higher the radiation resistance, for the same self-resonant element." Fat elements are physically shorter than thinner ones for the same resonant frequency, hence have a lower radiation resistance. 73, Roy K6XK/0 From k6mhe@mendolink.com Wed May 7 15:13:43 2003 From: k6mhe@mendolink.com (Dan Richardson) Date: Wed, 07 May 2003 07:13:43 -0700 Subject: [Antennas] Hairpin Monopole In-Reply-To: <001901c31494$7ab7d850$0100a8c0@monster> References: <20030507045159.14271.qmail@web20910.mail.yahoo.com> Message-ID: <5.1.0.14.2.20030507071233.00b3f428@mail.mendolink.com> At 08:27 AM 5/7/2003 -0400, Robert Lay wrote: >It's not a matter of what I think - it's a simple fact. The resistive >component of the antenna's input impedance (the radiation resistance) is >generally higher than a conventional, non-folded radiator. Not so! I suggest you check out http://www.w8ji.com/radiation_resistance.htm Danny, K6MHE From n7ws@yahoo.com Wed May 7 15:58:50 2003 From: n7ws@yahoo.com (Wes Stewart) Date: Wed, 7 May 2003 07:58:50 -0700 (PDT) Subject: [Antennas] Re: Hairpin monopoles In-Reply-To: <002301c31498$fa6344a0$552448ce@ncn.net> Message-ID: <20030507145850.87662.qmail@web20912.mail.yahoo.com> Thanks Roy for sparing me the task of making the same argument. --- Roy Koeppe wrote: > Oh, oh, regarding, > > "It's not a matter of what I think - it's a simple > fact. The resistive > component of the antenna's input impedance (the > radiation resistance) is > generally higher than a conventional, non-folded > radiator." > > > This old hams' tale has persisted throughout the > years and now rears its > head again? Radiation resistance and input impedance > are two entirely > separate things. With a folded element the input > impedance is simply > stepped up by transformer action alone, just as if > you installed a > transformer at the feedpoint. Radiation resistance, > on the other hand, > remains constant. Actually, most folded monopoles > have a slightly LOWER > radiation resistance than their single conductor > counterparts. This > obeys the law about "the thinner the conductor, the > higher the radiation > resistance, for the same self-resonant element." Fat > elements are > physically shorter than thinner ones for the same > resonant frequency, > hence have a lower radiation resistance. > > 73, Roy K6XK/0 > > > > > - - - > > Your moderator for this list is: > Larry Wilson KE1HZ antennas-owner@mailman.qth.net > _______________________________________________ > Antennas mailing list > Antennas@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/antennas __________________________________ Do you Yahoo!? The New Yahoo! Search - Faster. Easier. Bingo. http://search.yahoo.com From oz1bxn@qsl.net Wed May 7 17:04:06 2003 From: oz1bxn@qsl.net (Chris Jensen) Date: 07 May 2003 18:04:06 +0200 Subject: [Antennas] wiresize/frq on Quads? Message-ID: <1052323445.4937.10.camel@hack.freedom.dk> I am looking for a formula for calculating the loop size on HF Quads and loops in general. What I look for is a formula that takes the wire thickness into account! Also is it possible to convert American standard for wire thickness into European millimeters (mm)? Hope someone can help out ? vy73 de oz1bxn, Chris From w9dmk@crosslink.net Wed May 7 17:23:14 2003 From: w9dmk@crosslink.net (Robert Lay (W9DMK)) Date: Wed, 7 May 2003 12:23:14 -0400 Subject: [Antennas] Another Look at Efficiency References: <20030507145850.87662.qmail@web20912.mail.yahoo.com> Message-ID: <001801c314b4$f8a9eb20$0100a8c0@monster> It would appear that the efficiency of the multi-conductor antenna is not, as a result, higher. After looking it up in the only references that I have, it would appear that the true radiation resistance, as other contributors have pointed out, does not increase in fact (relative to ground and other losses) but is simply transformed to a higher value as seen at the feed point. I would have to presume from that, that the ground loss term appearing in the total real part of the impedance would also be transformed by the same amount. The ARRL Handbook says that the folded dipole "has the same ... total radiation resistance as an ordinary dipole." So, thanks for the correction. It is also interesting to note that the RSGB Radio Communication Handbook seems to contradict that, if we take their use of the term "radiation resistance" as being the same as ours. Quoting from page 12.33: "Since half the current flows in each wire, the radiation resistance referred to the centre of either is four times that of a simple dipole, ie 300 ohms approximately, which is particularly convenient for matching to standard ribbon feeder, though the higher impedance and wider bandwidth of an open-wire line greatly eases the problems of resonant feed lines, and this can be exploited to good effect for the development of multiband beams as discussed later." 73 de W9DMK (Bob Lay in Dahlgren, VA http://www.qsl.net/w9dmk From ve7hcb@rac.ca Wed May 7 18:50:02 2003 From: ve7hcb@rac.ca (Chris BONDE) Date: Wed, 07 May 2003 10:50:02 -0700 Subject: [Antennas] Questions! Message-ID: <4.3.1.1.20030507103445.00abaa10@mail.netidea.com> OK, whilst I try to keep a low profile, to learn without emotions, and submit unbiased responses, it appears that I have evoked some comments on the reponse to the answer to the original question. Probably forgotten by many as the thread progesses. Breifly the question, (in my understanding) was about using a relay in the radiating part of the antenna system to change (switch in/out sections) the physical length of such. The answer that I objected to, was not the technical part, but the lead in, which was: >Dear Osten, > >It's a totally ridiculous idea and isn't worth even trying. As you say, the >voltage is very high (the current is also very low) at the ends of a dipole. >Therefore, there isn't a relay in existence that can help you there. Did it >ever occur to you that if such an idea had any chance at all, someone would >have already tried it and published the results? In fact, the only antennas >that I have ever heard of that use relays, use the relay or relays for >switching in the transmission line - hopefully, at a point where the current >and voltage are consistent with the capability of the relay. The lead in that I would have prefered (especially if I had asked the question) would be similar to: >Osten, > >I'm not sure why you received so many mildly >hostile replies to your question, but I'll try to >help if I can. > >As some responders have pointed out, you >may have trouble with high voltage at the >locations of the relays. This is likely to >happen if you use smaller relays. However, >many hams have successfully used shorting >wires to change the length of their antennas. >Cut the antenna wire at the terminating length >for the higher band and insert a "dogbone" >insulator at that point. Solder a short wire to >one of the antenna wire ends, and attach an >alligator clip to the other end of the short wire. >Clip the short wire to the other antenna wire >to make the overall antenna length longer, >and unclip it to make it shorter. I have received a few replies off-reflector, all positive and helpful. From these, I would say the the writter of the first response is a respected instructor at a college, well known for his work in radio and has done much for the radio fraternity. Chris opr VE7HCB From ve7hcb@rac.ca Wed May 7 19:27:24 2003 From: ve7hcb@rac.ca (Chris BONDE) Date: Wed, 07 May 2003 11:27:24 -0700 Subject: [Antennas] Re: Hairpin monopoles In-Reply-To: <002301c31498$fa6344a0$552448ce@ncn.net> Message-ID: <4.3.1.1.20030507112241.00ab5500@mail.netidea.com> At 08:02 AM 2003-05-07 -0500, Roy Koeppe wrote: >Oh, oh, regarding, > >"It's not a matter of what I think - it's a simple fact. The resistive >component of the antenna's input impedance (the radiation resistance) is >generally higher than a conventional, non-folded radiator." > >. Actually, most folded monopoles have a slightly LOWER >radiation resistance than their single conductor counterparts. This >obeys the law about "the thinner the conductor, the higher the radiation >resistance, for the same self-resonant element." Fat elements are >physically shorter than thinner ones for the same resonant frequency, >hence have a lower radiation resistance. > >73, Roy K6XK/0 This seems to me to be a little out. To me the size of the conductor is not what changes the impedance, it is the number thereof, ie the transformer effect. The radiation resistance is just a method of explaination. Has anyone really measured radiation resistance? From what I understand it is used to explain what happens or whatever the missing part is in the equation. Now I have not studied antennas systems that much lately, but when I was, radiation resistance seemed to offer the most resistance in understanding ( after Poynting vector) Chris opr VE7HCB From farson@shaw.ca Wed May 7 20:05:06 2003 From: farson@shaw.ca (Adam Farson) Date: Wed, 07 May 2003 12:05:06 -0700 Subject: [Antennas] Questions! In-Reply-To: <4.3.1.1.20030507103445.00abaa10@mail.netidea.com> Message-ID: Chris, In fact, I have an antenna which incorporates a range-switching relay (although it is not currently erected.) This antenna is a Cushcraft AV-80 vertical, which has a tap-switching relay to select the CW or SSB portion of the band. I used to work the European 80m DX window on the AV-80 from my former QTH in Florida. The AV-80 is a base-loaded vertical, with a top capacity hat. The radiator is 11m tall, and elevated mounting (base 3m above ground) is recommended. The loading-network box incorporates a relay which switches a tap on the loading coil to select the CW or SSB sub-band. The relay contacts switch a relatively high-current, low-voltage point. The relay can be powered either from a separate control line, or by putting +12V DC on the centre conductor of the feedline. The point here is that a relay is fine for switching a low-voltage/high-current point in an RF network. Relays are not practical for switching "stretchers" onto the ends of a dipole, as the RF voltage at the end of a half-wave dipole (or a quarter-wave monopole) is likely to exceed the breakdown rating of any practical relay. Hence the use of parallel traps; these present a very high impedance at their resonant frequency, thus effectively isolating the "stretcher" from the basic radiator without the complications of an electro-mechanical switching device. Best 73, Adam, VA7OJ/AB4OJ North Vancouver, BC, Canada http://www.qsl.net/ab4oj/ From w5yr@att.net Wed May 7 20:20:51 2003 From: w5yr@att.net (George, W5YR) Date: Wed, 7 May 2003 14:20:51 -0500 Subject: [Antennas] Re: Hairpin monopoles References: <4.3.1.1.20030507112241.00ab5500@mail.netidea.com> Message-ID: <017b01c314cd$c6d6e850$0401a8c0@PS> As you express it, "radiation resistance" can be considered an "explanation." Since all the power delivered to an antenna must be either radiated or dissipated in heat (guess that is radiation also!), the ohmic resistance loss in the antenna structure is used to explain/determine the power not radiated but delivered. The remainder of the delivered power that is actually radiated is modeled as the power that a fictitious resistance - termed radiation resistance - would radiate if fed the same amount of power as that which is radiated. It is not a physical resistance, thus it cannot be identified, isolated, or directly measured, in a sense. But, it is a useful construct for accounting for radiated power. A similar situation is found in the notion of characteristic impedance of a transmission line, expressed in the form R+jX, where R is the resistive component and X is the reactive component. Lines operated at HF generally have reactance so small as to be negligible so we use Zo as a purely resistive value. At audio frequencies, however, X can take on quite large values and all the usual transmission line equations must deal with the complex nature of Zo. So, this is another instance wherein we use the notion of a resistance to define a property although it is not a physical resistor that can be identified and isolated. Neither does it dissipate any power! The resistive component of Zo is separate and apart from the ohmic and dielectric losses of the line which account for its dissipative losses. Although the matter is less clear in the r-f amplifier area, arguments have been presented that the "internal impedance" of such an amplifier is essentially resistive and shares the property of being non-dissipative. However artificial the radiation resistance construct may appear, it is of critical importance in understanding and computing the efficiency of an antenna. 73/72, George Amateur Radio W5YR - the Yellow Rose of Texas Fairview, TX 30 mi NE of Dallas in Collin county EM13QE "In the 57th year and it just keeps getting better!" ----- Original Message ----- From: "Chris BONDE" To: "Roy Koeppe" Cc: "Antennas reflector" Sent: Wednesday, May 07, 2003 1:27 PM Subject: Re: [Antennas] Re: Hairpin monopoles > At 08:02 AM 2003-05-07 -0500, Roy Koeppe wrote: > >Oh, oh, regarding, > > > >"It's not a matter of what I think - it's a simple fact. The resistive > >component of the antenna's input impedance (the radiation resistance) is > >generally higher than a conventional, non-folded radiator." > > > >. Actually, most folded monopoles have a slightly LOWER > >radiation resistance than their single conductor counterparts. This > >obeys the law about "the thinner the conductor, the higher the radiation > >resistance, for the same self-resonant element." Fat elements are > >physically shorter than thinner ones for the same resonant frequency, > >hence have a lower radiation resistance. > > > >73, Roy K6XK/0 > > This seems to me to be a little out. To me the size of the conductor is > not what changes the impedance, it is the number thereof, ie the > transformer effect. The radiation resistance is just a method of > explaination. Has anyone really measured radiation resistance? From what > I understand it is used to explain what happens or whatever the missing > part is in the equation. > > Now I have not studied antennas systems that much lately, but when I was, > radiation resistance seemed to offer the most resistance in understanding ( > after Poynting vector) > > Chris opr VE7HCB From k6mhe@mendolink.com Wed May 7 22:43:36 2003 From: k6mhe@mendolink.com (Dan Richardson) Date: Wed, 07 May 2003 14:43:36 -0700 Subject: [Antennas] wiresize/frq on Quads? In-Reply-To: <1052323445.4937.10.camel@hack.freedom.dk> Message-ID: <5.1.0.14.2.20030507144259.00b3f428@mail.mendolink.com> This should help you out: http://www.ilsco.com/IlscoHome/ilscoweb.nsf/htmlmedia/wire.html Danny K6MHE At 06:04 PM 5/7/2003 +0200, you wrote: >I am looking for a formula for calculating the loop size on HF Quads and >loops in general. > >What I look for is a formula that takes the wire thickness into account! > >Also is it possible to convert American standard for wire thickness into >European millimeters (mm)? > >Hope someone can help out ? > >vy73 de oz1bxn, Chris > > >- - - > >Your moderator for this list is: >Larry Wilson KE1HZ antennas-owner@mailman.qth.net >_______________________________________________ >Antennas mailing list >Antennas@mailman.qth.net >http://mailman.qth.net/mailman/listinfo/antennas From dufferjames@hotmail.com Wed May 7 23:00:36 2003 From: dufferjames@hotmail.com (James Duffer) Date: Wed, 07 May 2003 17:00:36 -0500 Subject: [Antennas] Re: Hairpin monopoles Message-ID: >It is not a physical resistance, thus it cannot be identified, isolated, or >directly measured, in a sense. But, it is a useful construct for accounting >for radiated power. It has benn stated: >A similar situation is found in the notion of characteristic impedance of a >transmission line, expressed in the form R+jX, where R is the resistive >component and X is the reactive component. Lines operated at HF generally >have reactance so small as to be negligible so we use Zo as a purely >resistive value. At audio frequencies, however, X can take on quite large >values and all the usual transmission line equations must deal with the >complex nature of Zo. > >So, this is another instance wherein we use the notion of a resistance to >define a property although it is not a physical resistor that can be >identified and isolated. Neither does it dissipate any power! The resistive >component of Zo is separate and apart from the ohmic and dielectric losses >of the line which account for its dissipative losses. An interesting analogy but leaves some questions. If the transmission line is terminated in a load that is equal to the transmission lines characteristic impedance, then what has frequency got to do with characteristic impedance???? The charateristic impedance is dependent on the physcial construction conductor diameter and distance of the conductors. I am beginning to think that you are referring to impedances that result from reflections of mismatched loads and characteristic impedances. There have been a couple of previous post that gave a satisfactory explanation of radiation resistance, and your explanation may be just fine, but the analogy leaves me wondering. Zo (characteristic impedance is not a figament of someones imagination, it is there and relatively constant regardless of impedances resulting from mismatched or reactive loads etc. Now lets hear more about the monopin hairpole.!! Jim, wd4air _________________________________________________________________ Tired of spam? Get advanced junk mail protection with MSN 8. http://join.msn.com/?page=features/junkmail From n7ws@yahoo.com Thu May 8 01:10:50 2003 From: n7ws@yahoo.com (Wes Stewart) Date: Wed, 7 May 2003 17:10:50 -0700 (PDT) Subject: [Antennas] Re: Hairpin monopoles In-Reply-To: Message-ID: <20030508001050.68759.qmail@web20904.mail.yahoo.com> --- James Duffer wrote: [snip] George's explanation is of course right on. > > An interesting analogy but leaves some questions. > If the transmission line > is terminated in a load that is equal to the > transmission lines > characteristic impedance, then what has frequency > got to do with > characteristic impedance???? The charateristic > impedance is dependent on > the physcial construction > conductor diameter and distance of the conductors. Characteristic impedance is dependent on R, L and C per unit length. R, L and sometimes C are frequency dependent. As George told you, the characteristic impedance is reactive, especially at audio frequencies. Terminating a reactive line with a real resistance causes the line to be mismatched. The mismatch is frequency dependent. If you want a simple way to explore this, I suggest that you go to: http://www.qsl.net/ac6la/tldetails.html and download the program. Once you install it, select Belden 9913 line and set the frequency to 0.001 MHz. Make the load R=50, X=0 and then look at the SWR. You should see that it is 1.77:1. If you terminate the line in its characteristic impedance; 50 -j28.8, then the line is matched, but you have a 1.77:1 mismatch at the input. (Assuming realitively short lengths) __________________________________ Do you Yahoo!? The New Yahoo! Search - Faster. Easier. Bingo. http://search.yahoo.com From Mike.Linden@boschrexroth-us.com Thu May 8 14:24:00 2003 From: Mike.Linden@boschrexroth-us.com (Linden, Mike (BRC-Hes)) Date: Thu, 8 May 2003 08:24:00 -0500 Subject: [Antennas] How To Build Multiband Dipole Like the Alpha Delta DX-EE? Message-ID: <0100CC198494914989B0C701453FC3BC03797A2C@brmail3.us.boschrexroth.com> I'd like to build a multiband dipole just like the Alpha Delta DX-EE to replace the homebrew coaxial trap dipole I currently have in my attic. Since the antenna will be in the attic, it doesn't need to be nearly as tough as a commercial antenna (I should be able to do it for a lot less than Alpha Delta's $100). Plus, I'd like to use my current antenna's balun on the new antenna and Alpha Delta doesn't offer theirs with a balun. Based on Alpha Delta's Web site, the antenna is about 40ft long and covers 10/15/20/40m. The antenna is comprised of three parallel dipoles. 10m is covered on one dipole, 15m on another, and 20/40m on the third. The third dipole appears to provide support for both 20m and 40m by placing an inductor (not a trap, according to Alpha Delta, because their is no capacitor) at the point which marks the end of the 20m section. Supposedly, this inductor acts as a choke at 20m effectively terminating the 20m section and acts as an inductive load on 40m effectively decreasing the length of the 40m section. Does anyone have plans for the design of such an antenna? I'm primarily looking for information on the inductor in the 20/40m combination dipole; what should the inductance be and how should I approach building such an inductor using common (hardware store) components? Thanks, Michael N9BDF PS The "Amateur Radio Emergency Communications Consistency Act" (HR 1417) and the "Amateur Radio Spectrum Protection Act" (HR 713 & S. 537) have been reintroduced in Congress. Please contact your Congressmen to ask for their support of these bills! See the following ARRL link for details: http://www.arrl.org/govrelations/ From w0jrm@arrl.net Thu May 8 15:15:40 2003 From: w0jrm@arrl.net (Rob Matherly) Date: 08 May 2003 09:15:40 -0500 Subject: [Antennas] need mobile antenna help... Message-ID: <1052403344.1023.6.camel@localhost.localdomain> Hi all; On my truck, there is a hole in the fender where someone used to have an external AM antenna (the regular antenna is in the windshield). I'm going to be installing a 2m rig soon, and would like to mount the antenna in this hole. Can anyone suggest a good antenna for this purpose? Maybe suggest a mount I could use? I've been told that I need to keep the antenna short if I want to do this type of installation. Is that correct? TIA -- 72/73/oo - Rob, w0jrm http://members.iowasocean.com/jimrob - w0jrm@arrl.net - AIM: w0jrm "I don't like noises... especially when there ain't supposed to be any" From dufferjames@hotmail.com Thu May 8 16:09:26 2003 From: dufferjames@hotmail.com (James Duffer) Date: Thu, 08 May 2003 10:09:26 -0500 Subject: [Antennas] Re: Hairpin monopoles Message-ID: >From: Wes Stewart >To: James Duffer , antennas@mailman.qth.net >Subject: Re: [Antennas] Re: Hairpin monopoles >Date: Wed, 7 May 2003 17:10:50 -0700 (PDT) > > >--- James Duffer wrote: >[snip] > >George's explanation is of course right on. > > > > > An interesting analogy but leaves some questions. > > If the transmission line > > is terminated in a load that is equal to the > > transmission lines > > characteristic impedance, then what has frequency > > got to do with > > characteristic impedance???? The charateristic > > impedance is dependent on > > the physcial construction > > conductor diameter and distance of the conductors. > >Characteristic impedance is dependent on R, L and C >per unit length. R, L and sometimes C are frequency >dependent. Which is dependent on the physical construction of the transmission line. Refer to the formulas for Zo of parallel or coaxial lines (Zo= 276 Log 2S/d where S is center to center distance between the conducior and d is diameter of conductor[same units], Zo= 138 log (b/a) where b is inside diameter of outer conductor and a is outside diameter of inner conductor. Wouldn't manufacturers of coaxial cable state that the characteristic impedance Zo is for example 50 Ohms at 100 Mhz if it was indeed dependent on operating frequency. Sorry but I am from Missouri and you have to "show me". In that line, I am going to visit the URL you referenced and ponder this some more, cause if I am wrong I want to know why and I will change my thinking when convinced. 73, Jim, wd4air >As George told you, the characteristic impedance is >reactive, especially at audio frequencies. >Terminating a reactive line with a real resistance >causes the line to be mismatched. The mismatch is >frequency dependent. > >If you want a simple way to explore this, I suggest >that you go to: > >http://www.qsl.net/ac6la/tldetails.html > >and download the program. > >Once you install it, select Belden 9913 line and set >the frequency to 0.001 MHz. Make the load R=50, X=0 >and then look at the SWR. You should see that it is >1.77:1. > >If you terminate the line in its characteristic >impedance; 50 -j28.8, then the line is matched, but >you have a 1.77:1 mismatch at the input. (Assuming >realitively short lengths) > > > >__________________________________ >Do you Yahoo!? >The New Yahoo! Search - Faster. Easier. Bingo. >http://search.yahoo.com _________________________________________________________________ The new MSN 8: smart spam protection and 2 months FREE* http://join.msn.com/?page=features/junkmail From w5yr@att.net Thu May 8 17:04:49 2003 From: w5yr@att.net (George, W5YR) Date: Thu, 8 May 2003 11:04:49 -0500 Subject: [Antennas] Re: Hairpin monopoles References: Message-ID: <002a01c3157b$8e4d30d0$0401a8c0@PS> I am sure that Wes and I would interested in knowing what you find out in your investigation. I don't know about Wes, but I feel that my contribution is to provide accurate information about topics with which I am familiar. Whether or not you choose to accept it is your choice - not my job! <:} For the record, however, 1. the characteristic impedance of any transmission line is a complex quantity of the form Zo = Ro+jXo 2. depending upon the frequency range involved, the reactive component Xo of Zo may or may not be of importance 3. coax cable manufacturers *do* provide the complex Zo values for their cables; the TLDetails program Wes referenced will show you what it is for each of many commercial cables, and the calculations within the program use the complex Zo values; 4. your geometric interpretation is a useful approximation, within certain frequency ranges, but is not universally applicable nor is it a formal definition of Zo 5. characteristic impedance is a complex quantity. 73/72, George Amateur Radio W5YR - the Yellow Rose of Texas Fairview, TX 30 mi NE of Dallas in Collin county EM13QE "In the 57th year and it just keeps getting better!" ----- Original Message ----- From: "James Duffer" To: ; Sent: Thursday, May 08, 2003 10:09 AM Subject: Re: [Antennas] Re: Hairpin monopoles > > > > >From: Wes Stewart > >To: James Duffer , antennas@mailman.qth.net > >Subject: Re: [Antennas] Re: Hairpin monopoles > >Date: Wed, 7 May 2003 17:10:50 -0700 (PDT) > > > > > >--- James Duffer wrote: > >[snip] > > > >George's explanation is of course right on. > > > > > > > > An interesting analogy but leaves some questions. > > > If the transmission line > > > is terminated in a load that is equal to the > > > transmission lines > > > characteristic impedance, then what has frequency > > > got to do with > > > characteristic impedance???? The charateristic > > > impedance is dependent on > > > the physcial construction > > > conductor diameter and distance of the conductors. > > > >Characteristic impedance is dependent on R, L and C > >per unit length. R, L and sometimes C are frequency > >dependent. > > Which is dependent on the physical construction of the transmission line. > Refer to the formulas for Zo of parallel or coaxial lines (Zo= 276 Log 2S/d > where S is center to center distance between the conducior and d is diameter > of conductor[same units], Zo= 138 log (b/a) where b is inside diameter of > outer conductor and a is outside diameter of inner conductor. > > Wouldn't manufacturers of coaxial cable state that the characteristic > impedance Zo is for example 50 Ohms at 100 Mhz if it was indeed dependent on > operating frequency. Sorry but I am from Missouri and you have to "show > me". > > In that line, I am going to visit the URL you referenced and ponder this > some more, cause if I am wrong I want to know why and I will change my > thinking when convinced. > > 73, Jim, wd4air > > > > > > > >As George told you, the characteristic impedance is > >reactive, especially at audio frequencies. > >Terminating a reactive line with a real resistance > >causes the line to be mismatched. The mismatch is > >frequency dependent. > > > >If you want a simple way to explore this, I suggest > >that you go to: > > > >http://www.qsl.net/ac6la/tldetails.html > > > >and download the program. > > > >Once you install it, select Belden 9913 line and set > >the frequency to 0.001 MHz. Make the load R=50, X=0 > >and then look at the SWR. You should see that it is > >1.77:1. > > > >If you terminate the line in its characteristic > >impedance; 50 -j28.8, then the line is matched, but > >you have a 1.77:1 mismatch at the input. (Assuming > >realitively short lengths) > > > > > > > >__________________________________ > >Do you Yahoo!? > >The New Yahoo! Search - Faster. Easier. Bingo. > >http://search.yahoo.com > > _________________________________________________________________ > The new MSN 8: smart spam protection and 2 months FREE* > http://join.msn.com/?page=features/junkmail > > - - - > > Your moderator for this list is: > Larry Wilson KE1HZ antennas-owner@mailman.qth.net > _______________________________________________ > Antennas mailing list > Antennas@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/antennas From e.j.forwood@juno.com Thu May 8 20:00:23 2003 From: e.j.forwood@juno.com (e.j.forwood@juno.com) Date: Thu, 8 May 2003 13:00:23 -0600 Subject: [Antennas] need mobile antenna help... Message-ID: <20030508.130030.916.0.e.j.forwood@juno.com> Same old formula for 1/4 wave (234/Freq in MHz) still works. 2 meters is easy to work with. Used to use a coat hanger stuck out the top of a Gonset Communicator II. You can probably find an old telescoping auto radio antenna (like the one that was probably in the hole originally) and use it. Just telescope it out to the desired length. 73 de Jerry, K�EJF On 08 May 2003 09:15:40 -0500 Rob Matherly writes: > Hi all; > > On my truck, there is a hole in the fender where someone used to > have an > external AM antenna (the regular antenna is in the windshield). > I'm > going to be installing a 2m rig soon, and would like to mount the > antenna in this hole. > > Can anyone suggest a good antenna for this purpose? Maybe suggest > a > mount I could use? I've been told that I need to keep the antenna > short > if I want to do this type of installation. Is that correct? > > TIA > > -- > 72/73/oo - Rob, w0jrm > http://members.iowasocean.com/jimrob - w0jrm@arrl.net - AIM: w0jrm > "I don't like noises... especially when there ain't supposed to be > any" > > - - - > > Your moderator for this list is: > Larry Wilson KE1HZ antennas-owner@mailman.qth.net > _______________________________________________ > Antennas mailing list > Antennas@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/antennas > > E. Jerold (Jerry) Forwood From dethomas@hiwaay.net Thu May 8 21:13:42 2003 From: dethomas@hiwaay.net (Dave Thomas) Date: Thu, 8 May 2003 15:13:42 -0500 Subject: [Antennas] Fiberglass Paint Message-ID: I need to paint the fiberglass spreaders for a quad I recently obtained. They are presently in their manufactured state (never used but 20 years old) and should be protected from UV. I prefer to color them green for camouflage with spray paint(Krylon) from Wal-Mart. I have heard comments as to the right and wrong types of paint (another reflector) with respect to it's conductive properties. I am not familiar with this problem and wondered if anyone else was. Thanks, Dave Thomas N4CLR From n4sl@yahoo.com Thu May 8 21:17:05 2003 From: n4sl@yahoo.com (Steve L.) Date: Thu, 8 May 2003 13:17:05 -0700 (PDT) Subject: [Antennas] Fiberglass Paint In-Reply-To: Message-ID: <20030508201705.49733.qmail@web40811.mail.yahoo.com> HI Dave, I'm sure the chemical experts will jump on this, but I sand them, use a tack cloth to get rid of the dust and spray them with Epoxy Primer in flat black, then paint them w/ any spray paint you prefer for color. 73, Steve N4SL --- Dave Thomas wrote: > I need to paint the fiberglass spreaders for a quad > I recently obtained. > They are presently in their manufactured state > (never used but 20 years old) > and should be protected from UV. I prefer to color > them green for camouflage > with spray paint(Krylon) from Wal-Mart. I have heard > comments as to the > right and wrong types of paint (another reflector) > with respect to it's > conductive properties. I am not familiar with this > problem and wondered if > anyone else was. > > Thanks, > > Dave Thomas N4CLR > > > > - - - > > Your moderator for this list is: > Larry Wilson KE1HZ antennas-owner@mailman.qth.net > _______________________________________________ > Antennas mailing list > Antennas@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/antennas __________________________________ Do you Yahoo!? The New Yahoo! Search - Faster. Easier. Bingo. http://search.yahoo.com From ke4hie@alaweb.com Thu May 8 21:31:25 2003 From: ke4hie@alaweb.com (John Brown) Date: Thu, 8 May 2003 15:31:25 -0500 Subject: [Antennas] need mobile antenna help... References: <1052403344.1023.6.camel@localhost.localdomain> Message-ID: <003101c315a0$cccec740$7bdc6cd8@Home> Is the hole on top of the fender (like most Fords) or on the side of the fender. What size is the hole and can it be accessed easily from the backside of the fender? John - KE4HIE ----- Original Message ----- From: "Rob Matherly" To: Sent: Thursday, May 08, 2003 9:15 AM Subject: [Antennas] need mobile antenna help... > Hi all; > > On my truck, there is a hole in the fender where someone used to have an > external AM antenna (the regular antenna is in the windshield). I'm > going to be installing a 2m rig soon, and would like to mount the > antenna in this hole. > > Can anyone suggest a good antenna for this purpose? Maybe suggest a > mount I could use? I've been told that I need to keep the antenna short > if I want to do this type of installation. Is that correct? > > TIA > > -- > 72/73/oo - Rob, w0jrm > http://members.iowasocean.com/jimrob - w0jrm@arrl.net - AIM: w0jrm > "I don't like noises... especially when there ain't supposed to be any" > > - - - > > Your moderator for this list is: > Larry Wilson KE1HZ antennas-owner@mailman.qth.net > _______________________________________________ > Antennas mailing list > Antennas@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/antennas From royanjoy@ncn.net Thu May 8 22:53:40 2003 From: royanjoy@ncn.net (Roy Koeppe) Date: Thu, 8 May 2003 16:53:40 -0500 Subject: [Antennas] Re: Fiberglass paint Message-ID: <002201c315ac$49fbc1e0$6c2448ce@ncn.net> "I need to paint the fiberglass spreaders for a quad...(etc.)" FYI...you can purchase exotic paints such as 'epoxy paint.' Supposed to be very durable and I presume a fair dielectric. 73, Roy K6XK From n7ws@yahoo.com Fri May 9 00:32:15 2003 From: n7ws@yahoo.com (Wes Stewart) Date: Thu, 8 May 2003 16:32:15 -0700 (PDT) Subject: [Antennas] Re: Hairpin monopoles In-Reply-To: Message-ID: <20030508233215.67129.qmail@web20905.mail.yahoo.com> --- James Duffer wrote: > > > > >From: Wes Stewart > >To: James Duffer , > antennas@mailman.qth.net > >Subject: Re: [Antennas] Re: Hairpin monopoles > >Date: Wed, 7 May 2003 17:10:50 -0700 (PDT) > > > > > >--- James Duffer wrote: > >[snip] > > > >George's explanation is of course right on. > > > > > > > > An interesting analogy but leaves some > questions. > > > If the transmission line > > > is terminated in a load that is equal to the > > > transmission lines > > > characteristic impedance, then what has > frequency > > > got to do with > > > characteristic impedance???? The charateristic > > > impedance is dependent on > > > the physcial construction > > > conductor diameter and distance of the > conductors. > > > >Characteristic impedance is dependent on R, L and C > >per unit length. R, L and sometimes C are > frequency > >dependent. > > Which is dependent on the physical construction of > the transmission line. > Refer to the formulas for Zo of parallel or coaxial > lines (Zo= 276 Log 2S/d > where S is center to center distance between the > conducior and d is diameter > of conductor[same units], Zo= 138 log (b/a) where b > is inside diameter of > outer conductor and a is outside diameter of inner > conductor. > > Wouldn't manufacturers of coaxial cable state that > the characteristic > impedance Zo is for example 50 Ohms at 100 Mhz if it > was indeed dependent on > operating frequency. Sorry but I am from Missouri > and you have to "show > me". Not me. I'm lettin' George do it :) __________________________________ Do you Yahoo!? The New Yahoo! Search - Faster. Easier. Bingo. http://search.yahoo.com From elemmon@impulse.net Fri May 9 01:16:31 2003 From: elemmon@impulse.net (Eric Lemmon) Date: Thu, 08 May 2003 17:16:31 -0700 Subject: [Antennas] Fiberglass Paint References: Message-ID: <3EBAF35F.64A05874@impulse.net> Dave, Decibel Products has an application note on their website about what paint to use on fiberglass radomes. The term "radome" includes the fiberglass tube that encloses the elements of vertical colinear antennas. You might also check with RFS/Celwave for the paint they recommend for their Stationmaster antennas. As I recall, Sherwin-Williams is one of the few manufacturers of the special polyester epoxy paint that sticks to fiberglass and is RF transparent. The same stuff should work just fine on fiberglass spreader bars. Be very careful about using discount-store paint. Not only might the cheap paint contain pigments that are conductive, but the formulation may not be consistent between batches. 73, Eric Lemmon WB6FLY Dave Thomas wrote: > > I need to paint the fiberglass spreaders for a quad I recently obtained. > They are presently in their manufactured state (never used but 20 years old) > and should be protected from UV. I prefer to color them green for camouflage > with spray paint(Krylon) from Wal-Mart. I have heard comments as to the > right and wrong types of paint (another reflector) with respect to it's > conductive properties. I am not familiar with this problem and wondered if > anyone else was. > > Thanks, > > Dave Thomas N4CLR > > - - - > > Your moderator for this list is: > Larry Wilson KE1HZ antennas-owner@mailman.qth.net > _______________________________________________ > Antennas mailing list > Antennas@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/antennas From W1GOR@Maine.RR.Com Fri May 9 01:25:01 2003 From: W1GOR@Maine.RR.Com (W1GOR) Date: Thu, 8 May 2003 20:25:01 -0400 Subject: [Antennas] Fiberglass Paint References: Message-ID: <006e01c315c1$71f10c40$8bd7c618@maine.rr.com> Dave, Any paint that does NOT contain metallic pigment or any metallic content will be suitable for your application. I've used latex-based outdoor paints for similar applications such as yours. If you prefer an oil-based paint, check the ingredients of Rustoleum paints. They are among the toughest outdoor paints, and will work very well for you, providing the paint has no metallic content. Several years ago, I painted the weather-worn radome of a Decibel Products DB-220 vertical with high-gloss white Rustoleum. It looks as good as new, and there have been no changes in VSWR. 73, Larry ----- Original Message ----- From: "Dave Thomas" Sent: Thursday, May 08, 2003 16:13 Subject: [Antennas] Fiberglass Paint > I need to paint the fiberglass spreaders for a quad I recently obtained. > They are presently in their manufactured state (never used but 20 years old) > and should be protected from UV. I prefer to color them green for camouflage > with spray paint(Krylon) from Wal-Mart. I have heard comments as to the > right and wrong types of paint (another reflector) with respect to it's > conductive properties. I am not familiar with this problem and wondered if > anyone else was. > > Thanks, > > Dave Thomas N4CLR > > > > - - - > > Your moderator for this list is: > Larry Wilson KE1HZ antennas-owner@mailman.qth.net > _______________________________________________ > Antennas mailing list > Antennas@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/antennas From w0jrm@arrl.net Fri May 9 06:49:29 2003 From: w0jrm@arrl.net (Rob Matherly) Date: 09 May 2003 00:49:29 -0500 Subject: [Antennas] need mobile antenna help... In-Reply-To: <003101c315a0$cccec740$7bdc6cd8@Home> References: <1052403344.1023.6.camel@localhost.localdomain> <003101c315a0$cccec740$7bdc6cd8@Home> Message-ID: <1052459372.1023.37.camel@localhost.localdomain> On Thu, 2003-05-08 at 15:31, John Brown wrote: > Is the hole on top of the fender (like most Fords) or on the side of the > fender. > What size is the hole and can it be accessed easily from the backside of the > fender? I guess I shoulda been more specific :^) Here's all the info: It's a 1986 full-size Chevy Blazer. There wasn't originaly a hole there, someone drilled it (and apparently widened it with a file). It appears to be larger than 3/4". It's on top of the fender, and it's flat all around (for the most part). There's some holes in the backside of the fender where I can reach in, but the movement is kinda limited. -- 72/73/oo - Rob, w0jrm http://members.iowasocean.com/jimrob - w0jrm@arrl.net - AIM: w0jrm "I don't like noises... especially when there ain't supposed to be any" From ka7hbb@earthlink.net Fri May 9 09:07:08 2003 From: ka7hbb@earthlink.net (Mike Nason) Date: Fri, 9 May 2003 01:07:08 -0700 Subject: [Antennas] need mobile antenna help... References: <1052403344.1023.6.camel@localhost.localdomain> <003101c315a0$cccec740$7bdc6cd8@Home> <1052459372.1023.37.camel@localhost.localdomain> Message-ID: <002101c31601$fecb71b0$0100a8c0@ATHLON> Okay, Again, I'd look at the Radio Shack mount that they are getting rid of. The top is ~1 1/2" or so, kind of a tapered cone with a 3/8-24 thread in the top. It's made to drop into a hole that's a little bigger than 5/8" because the bottom is basically a SO239 connector with a 5/8 fender washer and nut. You screw on your PL259 on the bottom. These things aren't listed on their web page but in the stores there discounted because they are dropping them out of their line. There somewhere around $8 now. It should fill the hole and you can run a Hustler SF-2 Buck Buster 5/8 wave or a CG144 5.2 DB collinear and still be able to change it out for a Ham stick for HF if you want to,. Mike ----- Original Message ----- From: "Rob Matherly" To: Sent: Thursday, May 08, 2003 10:49 PM Subject: Re: [Antennas] need mobile antenna help... > On Thu, 2003-05-08 at 15:31, John Brown wrote: > > Is the hole on top of the fender (like most Fords) or on the side of the > > fender. > > What size is the hole and can it be accessed easily from the backside of the > > fender? > > I guess I shoulda been more specific :^) > > Here's all the info: It's a 1986 full-size Chevy Blazer. There wasn't > originaly a hole there, someone drilled it (and apparently widened it > with a file). It appears to be larger than 3/4". It's on top of the > fender, and it's flat all around (for the most part). There's some > holes in the backside of the fender where I can reach in, but the > movement is kinda limited. > > -- > 72/73/oo - Rob, w0jrm > http://members.iowasocean.com/jimrob - w0jrm@arrl.net - AIM: w0jrm > "I don't like noises... especially when there ain't supposed to be any" > > - - - > > Your moderator for this list is: > Larry Wilson KE1HZ antennas-owner@mailman.qth.net > _______________________________________________ > Antennas mailing list > Antennas@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/antennas From dufferjames@hotmail.com Fri May 9 14:10:28 2003 From: dufferjames@hotmail.com (James Duffer) Date: Fri, 09 May 2003 08:10:28 -0500 Subject: [Antennas] Xms Line Zo,Formerly Hairpin monopoles Message-ID: I am not questioning your desire for accuracy, and I know you would not deliberately mislead, but there may be some questionable content....I recall that you erred previously on the impedance of a folded dipole...at least I think it was you.... snip >I am sure that Wes and I would interested in knowing what you find out in >your investigation. I don't know about Wes, but I feel that my contribution >is to provide accurate information about topics with which I am familiar. >Whether or not you choose to accept it is your choice - not my job! <:} I really haven't went to extremes in researching this....just reviewing Chapter 19 of the "ARRL Handbook for Radio Amateurs" and the "Antenna Engineering Handbook" Third edition by Richard Johnson, Chapter 42 "Transmission Lines and Waveguides by Roderic V. Lowman. I also visited the URL furnished by Wes which was more appropriate forfinding impedance resultingb from mismatched transmission lines rather than the charateristic impedance Zo sometimes referred to as the "surge impedance". >For the record, however, > >1. the characteristic impedance of any transmission line is a complex >quantity of the form Zo = Ro+jXo With the jXo being insignificant for most applications. Zo equals the square root (L/C) where L and C is equal to the distributed linear capacitance and inductance and is determined primarily by the geometry of the transmission line. > >2. depending upon the frequency range involved, the reactive component Xo >of >Zo may or may not be of importance *****DEFINITELY******** Especially when the frequency range is within the normal range for the particular transmission lines application (where line losses are tolerable) >3. coax cable manufacturers *do* provide the complex Zo values for their >cables; the TLDetails program Wes referenced will show you what it is for >each of many commercial cables, and the calculations within the program use >the complex Zo values; Not typically available or indicated on coaxial cable see charts provided with above mentioned reference material. Refer to the chart on Table 19.1 Characteristics of Commonly Used Transmission Lines, Page 19.3 of the 1997 ARRL Handbook for Radio Amateurs. I hope you are not getting the pf per foot column confused. The Zo is listed in the first column and it is not a "complex" value. >4. your geometric interpretation is a useful approximation, within certain >frequency ranges, but is not universally applicable nor is it a formal >definition of Zo Agree that it is not the "formal definition of Zo", however it is the most common method of determining it if you do not have the means to measure the linear distributed capacitance and inductance. Again refer to most text on transmission lines especially two wire and coax. If you want to "pick at knits", it could become more complicated.....but that isn't necessary. If you were to construct your on two wire transmission you coluld get a good approximation by the formula Zo=276Log2S/d. Agreed that proximity of a ground plane does actually influence the Zo, but why convolute the process with frequency? >5. characteristic impedance is a complex quantity. If you desire to make it so, by bringing in a bunch of insignifacnt factors other than geomety of the line. > >73/72, George >Amateur Radio W5YR - the Yellow Rose of Texas >Fairview, TX 30 mi NE of Dallas in Collin county EM13QE >"In the 57th year and it just keeps getting better!" > > If you desire to compare radiation resistance with Zo in and analogy manner, its all right. The world will not be any worse for it. However I see a big difference and little relationship between them. 73, Jim, wd4air\\ @hotmail.com> >To: ; >Sent: Thursday, May 08, 2003 10:09 AM >Subject: Re: [Antennas] Re: Hairpin monopoles > > > > > > > > > > >From: Wes Stewart > > >To: James Duffer , antennas@mailman.qth.net > > >Subject: Re: [Antennas] Re: Hairpin monopoles > > >Date: Wed, 7 May 2003 17:10:50 -0700 (PDT) > > > > > > > > >--- James Duffer wrote: > > >[snip] > > > > > >George's explanation is of course right on. > > > > > > > > > > > An interesting analogy but leaves some questions. > > > > If the transmission line > > > > is terminated in a load that is equal to the > > > > transmission lines > > > > characteristic impedance, then what has frequency > > > > got to do with > > > > characteristic impedance???? The charateristic > > > > impedance is dependent on > > > > the physcial construction > > > > conductor diameter and distance of the conductors. > > > > > >Characteristic impedance is dependent on R, L and C > > >per unit length. R, L and sometimes C are frequency > > >dependent. > > > > Which is dependent on the physical construction of the transmission >line. > > Refer to the formulas for Zo of parallel or coaxial lines (Zo= 276 Log >2S/d > > where S is center to center distance between the conducior and d is >diameter > > of conductor[same units], Zo= 138 log (b/a) where b is inside diameter >of > > outer conductor and a is outside diameter of inner conductor. > > > > Wouldn't manufacturers of coaxial cable state that the characteristic > > impedance Zo is for example 50 Ohms at 100 Mhz if it was indeed >dependent >on > > operating frequency. Sorry but I am from Missouri and you have to "show > > me". > > > > In that line, I am going to visit the URL you referenced and ponder this > > some more, cause if I am wrong I want to know why and I will change my > > thinking when convinced. > > > > 73, Jim, wd4air > > > > > > > > > > > > > > >As George told you, the characteristic impedance is > > >reactive, especially at audio frequencies. > > >Terminating a reactive line with a real resistance > > >causes the line to be mismatched. The mismatch is > > >frequency dependent. > > > > > >If you want a simple way to explore this, I suggest > > >that you go to: > > > > > >http://www.qsl.net/ac6la/tldetails.html > > > > > >and download the program. > > > > > >Once you install it, select Belden 9913 line and set > > >the frequency to 0.001 MHz. Make the load R=50, X=0 > > >and then look at the SWR. You should see that it is > > >1.77:1. > > > > > >If you terminate the line in its characteristic > > >impedance; 50 -j28.8, then the line is matched, but > > >you have a 1.77:1 mismatch at the input. (Assuming > > >realitively short lengths) > > > > > > > > > > > >__________________________________ > > >Do you Yahoo!? > > >The New Yahoo! Search - Faster. Easier. Bingo. > > >http://search.yahoo.com > > > > _________________________________________________________________ > > The new MSN 8: smart spam protection and 2 months FREE* > > http://join.msn.com/?page=features/junkmail > > > > - - - > > > > Your moderator for this list is: > > Larry Wilson KE1HZ antennas-owner@mailman.qth.net > > _______________________________________________ > > Antennas mailing list > > Antennas@mailman.qth.net > > http://mailman.qth.net/mailman/listinfo/antennas > >- - - > >Your moderator for this list is: >Larry Wilson KE1HZ antennas-owner@mailman.qth.net >_______________________________________________ >Antennas mailing list >Antennas@mailman.qth.net >http://mailman.qth.net/mailman/listinfo/antennas _________________________________________________________________ The new MSN 8: advanced junk mail protection and 2 months FREE* http://join.msn.com/?page=features/junkmail From w2rds@arrl.net Fri May 9 14:21:03 2003 From: w2rds@arrl.net (Rick Stoneking) Date: Fri, 09 May 2003 09:21:03 -0400 Subject: [Antennas] KT-34A Model? Message-ID: <5.1.0.14.0.20030509091900.0349fb30@netmail.home.com> Hello all, Does anybody have a EZNEC (or other) model for the KT-34A triband antenna? Thanks, Rick W2RDS From w5yr@att.net Fri May 9 20:27:19 2003 From: w5yr@att.net (George, W5YR) Date: Fri, 9 May 2003 14:27:19 -0500 Subject: [Antennas] Xms Line Zo,Formerly Hairpin monopoles References: Message-ID: <015501c31661$027f45c0$0401a8c0@PS> Jim, you seem to prefer keeping this discussion on the reflector when your objections properly belong in a private forum. However, that is your choice . . . Let me be as brief as I can. You have chosen to view a very complex subject through the convenient knothole of "typical amateur radio HF" practices. Consequently, you have reached conclusions which while they work well enough in that area, are NOT generally true, and neither Wes nor I are in error for pointing this out to you. Consult any undergraduate level text on transmission line theory and you will find from the earliest discussion of first principles that characteristic impedance is a frequency-dependent property of a line, any line, any frequency, any termination, any construction, etc. Now, you will also find that given certain fortuitous relationships between certain line parameters you obtain the famous Heaviside line which amounts to an all-pass filter. However, such a line has little if any practical application due to the constraints placed upon it to meet these conditions. So, in the real world, we proceed further and find that certain terms involved in the basic equations that define Zo = Ro +jXo take on small but not necessarily negligible values within certain frequency ranges. Not zero values, note, just small possibly negligible values. As amateurs, we take advantage of this and just ignore the Xo component of Zo although it is not zero and is stated clearly for you in the TLDetails program for each line in its list. You can choose in the program to either ignore Xo or to use it. Once we elect to regard Zo as a purely real quantity, we then are free to make all sorts of convenient assumptions and approximations, including calculating Zo of a given line structure from its geometrical format, etc. So, that is where you are coming from: the world of approximations and the elimination of complicating matters like complex Zo. The information I gave you, and which Wes confirmed, was from the formal world of actual definition, etc. which applies to *all* line applications regardless of frequency, etc. You choose to claim that what I say is incorrect because it disagrees with your understanding of the matter. You are certainly free to reach that conclusion and even to state it publicly as you insist upon doing. Nonetheless, your conclusions are not correct in the general case nor am I incorrect in stating the points that I did. I hope that this will clarify at least my position in this tiresome matter. I have said all that I intend to say since you feel compelled to doubt it all in the first place, based upon your limited outlook. And, yes, I am the unfortunate who posted an error concerning the driving-point impedance of a folded dipole. Now, for the benefit of the audience, how many other errors have you found? Enough! Go forth and hold good thoughts and stay well. 73/72, George Amateur Radio W5YR - the Yellow Rose of Texas Fairview, TX 30 mi NE of Dallas in Collin county EM13QE "In the 57th year and it just keeps getting better!" ----- Original Message ----- From: "James Duffer" To: ; ; Sent: Friday, May 09, 2003 8:10 AM Subject: [Antennas] Xms Line Zo,Formerly Hairpin monopoles > I am not questioning your desire for accuracy, and I know you would not > deliberately mislead, but there may be some questionable content....I recall > that you erred previously on the impedance of a folded dipole...at least I > think it was you.... > > snip > > >I am sure that Wes and I would interested in knowing what you find out in > >your investigation. I don't know about Wes, but I feel that my contribution > >is to provide accurate information about topics with which I am familiar. > >Whether or not you choose to accept it is your choice - not my job! <:} > > I really haven't went to extremes in researching this....just reviewing > Chapter 19 of the "ARRL Handbook for Radio Amateurs" and the "Antenna > Engineering Handbook" Third edition by Richard Johnson, Chapter 42 > "Transmission Lines and Waveguides by Roderic V. Lowman. I also visited the > URL furnished by Wes which was more appropriate forfinding impedance > resultingb from mismatched transmission lines rather than the charateristic > impedance Zo sometimes referred to as the "surge impedance". > > > >For the record, however, > > > >1. the characteristic impedance of any transmission line is a complex > >quantity of the form Zo = Ro+jXo > > With the jXo being insignificant for most applications. Zo equals the > square root (L/C) where L and C is equal to the distributed linear > capacitance and inductance and is determined primarily by the geometry of > the transmission line. > > > >2. depending upon the frequency range involved, the reactive component Xo > >of > >Zo may or may not be of importance > > *****DEFINITELY******** Especially when the frequency range is within the > normal range for the particular transmission lines application (where line > losses are tolerable) > > >3. coax cable manufacturers *do* provide the complex Zo values for their > >cables; the TLDetails program Wes referenced will show you what it is for > >each of many commercial cables, and the calculations within the program use > >the complex Zo values; > > > Not typically available or indicated on coaxial cable see charts provided > with above mentioned reference material. Refer to the chart on Table 19.1 > Characteristics of Commonly Used Transmission Lines, Page 19.3 of the 1997 > ARRL Handbook for Radio Amateurs. I hope you are not getting the pf per > foot column confused. The Zo is listed in the first column and it is not a > "complex" value. > > > >4. your geometric interpretation is a useful approximation, within certain > >frequency ranges, but is not universally applicable nor is it a formal > >definition of Zo > > Agree that it is not the "formal definition of Zo", however it is the most > common method of determining it if you do not have the means to measure the > linear distributed capacitance and inductance. Again refer to most text on > transmission lines especially two wire and coax. If you want to "pick at > knits", it could become more complicated.....but that isn't necessary. If > you were to construct your on two wire transmission you coluld get a good > approximation by the formula Zo=276Log2S/d. Agreed that proximity of a > ground plane does actually influence the Zo, but why convolute the process > with frequency? > > >5. characteristic impedance is a complex quantity. > > If you desire to make it so, by bringing in a bunch of insignifacnt factors > other than geomety of the line. > > > >73/72, George > >Amateur Radio W5YR - the Yellow Rose of Texas > >Fairview, TX 30 mi NE of Dallas in Collin county EM13QE > >"In the 57th year and it just keeps getting better!" > > > > > > If you desire to compare radiation resistance with Zo in and analogy manner, > its all right. The world will not be any worse for it. However I see a big > difference and little relationship between them. > > 73, Jim, wd4air\\ > > > > @hotmail.com> > >To: ; > >Sent: Thursday, May 08, 2003 10:09 AM > >Subject: Re: [Antennas] Re: Hairpin monopoles > > > > > > > > > > > > > > > > >From: Wes Stewart > > > >To: James Duffer , antennas@mailman.qth.net > > > >Subject: Re: [Antennas] Re: Hairpin monopoles > > > >Date: Wed, 7 May 2003 17:10:50 -0700 (PDT) > > > > > > > > > > > >--- James Duffer wrote: > > > >[snip] > > > > > > > >George's explanation is of course right on. > > > > > > > > > > > > > > An interesting analogy but leaves some questions. > > > > > If the transmission line > > > > > is terminated in a load that is equal to the > > > > > transmission lines > > > > > characteristic impedance, then what has frequency > > > > > got to do with > > > > > characteristic impedance???? The charateristic > > > > > impedance is dependent on > > > > > the physcial construction > > > > > conductor diameter and distance of the conductors. > > > > > > > >Characteristic impedance is dependent on R, L and C > > > >per unit length. R, L and sometimes C are frequency > > > >dependent. > > > > > > Which is dependent on the physical construction of the transmission > >line. > > > Refer to the formulas for Zo of parallel or coaxial lines (Zo= 276 Log > >2S/d > > > where S is center to center distance between the conducior and d is > >diameter > > > of conductor[same units], Zo= 138 log (b/a) where b is inside diameter > >of > > > outer conductor and a is outside diameter of inner conductor. > > > > > > Wouldn't manufacturers of coaxial cable state that the characteristic > > > impedance Zo is for example 50 Ohms at 100 Mhz if it was indeed > >dependent > >on > > > operating frequency. Sorry but I am from Missouri and you have to "show > > > me". > > > > > > In that line, I am going to visit the URL you referenced and ponder this > > > some more, cause if I am wrong I want to know why and I will change my > > > thinking when convinced. > > > > > > 73, Jim, wd4air > > > > > > > > > > > > > > > > > > > > > >As George told you, the characteristic impedance is > > > >reactive, especially at audio frequencies. > > > >Terminating a reactive line with a real resistance > > > >causes the line to be mismatched. The mismatch is > > > >frequency dependent. > > > > > > > >If you want a simple way to explore this, I suggest > > > >that you go to: > > > > > > > >http://www.qsl.net/ac6la/tldetails.html > > > > > > > >and download the program. > > > > > > > >Once you install it, select Belden 9913 line and set > > > >the frequency to 0.001 MHz. Make the load R=50, X=0 > > > >and then look at the SWR. You should see that it is > > > >1.77:1. > > > > > > > >If you terminate the line in its characteristic > > > >impedance; 50 -j28.8, then the line is matched, but > > > >you have a 1.77:1 mismatch at the input. (Assuming > > > >realitively short lengths) > > > > From k6acz@earthlink.net Sat May 10 00:47:46 2003 From: k6acz@earthlink.net (Alan C. Zack) Date: Fri, 09 May 2003 16:47:46 -0700 Subject: [Antennas] LPT-620 Mini Tower Message-ID: <3EBC3E22.85AB6D0@earthlink.net> A year ago I purchased a Force12 LPT-620 mini-tower. The description for the LPT-620 indicates it can be raised and lowered more easily by using an electric drill on it's winch but there are no instructions on how to do so. I had presented the question of how to attach a drill to the winch on this reflector and received several good responses with suggestions. Unfortunately, none were viable. I attended the Visalia Intl DX Convention this past weekend. I went to the F12 booth and discussed raising my LPT-620 using an electric drill with Tom, N6BT, owner of F12. Tom indicated I needed a sleeve or loop assembly that slips over the crank handle threads that would allow the drill to be used without damaging the threads. I asked where do I obtain such an item. Tom stated they come with the winch. I advised Tom my winch did not have one. Tom stated that was not his problem and refused to discuss it with me further and started talking to someone else at the booth. My contention is that although F12 purchases the winch from a sub-contractor it is still his responsibility to assure the winch assembly is complete when he installs it on his tower assemblies. Furthermore, I received the tower with the winch handle reversed (pointing inward rather than out) for shipping. Someone at F12 had to remove the winch handle, along with this loop/sleeve piece, to reverse the handle, and may have forgotten to replace it. In any case, I believe F12 owes me this winch crank sleeve/loop piece which is part of the tower I purchased. Tom says it is my problem with the winch company. I feel Tom should look around his shop to see if he has any of these pieces laying around to send me, and if not, request one for me from his winch vendor. Believe me, when I was a Procurement Quality Engineer with Boeing I could never get away with attempting to sell an electronic component to a customer that was missing part of its assembly and blame it on a sub-contractor who sold Boeing a less than complete part. So I am missing this piece that I need to protect the threads on my winch in order to use a drill to raise or lower my tower. Does anyone out there know what this part is and how I may obtain one? The winch is model WG1500 manufactured by Dutton-Lainson in Hastings, NE. I have written a letter to Dutton-Lainson but have not received a reply as yet. -- __________________________________________________________________________ Alan Zack Amateur Radio Station K6ACZ Anaheim, Southern California, USA Home of the World Series Winners ANGELS Quality Engineer, The Boeing Company, Retired Aviation Chief Warrant Officer, U.S. Coast Guard, Retired U.S. Coast Guard, Always Ready, Always There Every hour, Every day, Around the Clock and Around the World SEMPER PARATUS From ornitz@tricon.net Sat May 10 01:47:16 2003 From: ornitz@tricon.net (Barry L. Ornitz) Date: Fri, 9 May 2003 20:47:16 -0400 Subject: [Antennas] Complex Characteristic Impedance of Cables References: <20030509055603.3E88A3289DC@mailman.qth.net> Message-ID: <001801c3168d$b51bbe80$4b5b62d8@naxs.com> Use a fixed width font to view the following... James Duffer, WD4AIR, is still somewhat confused that the characteristic impedance of real coaxial cable and other real transmission lines can be complex (have both real and quadrature [imaginary, SQRT(-1)] parts. A transmission line can be described as a combination of distributed series elements and distributed shunt elements. All that "distributed" means is that the values are per unit length. The differential model usually found is: -----R--L--o----o----- where: R = resistance/meter | | L = inductance/meter C G C = capacitance/meter | | G = conductance/meter -----------o----o----- You can derive the characteristic impedance from this as: Zo = SQRT((R+jwL)/(G+jwC)) At very high frequencies, w = 2*pi*f, the imaginary terms are much larger than the real terms so the characteristic impedance approaches SQRT(L/C). Now in real cables, especially at low frequencies, the series resistance term is several orders of magnitude higher than the shunt conductance term and both can be large compared to the reactive terms. This makes real coaxial cables have a strongly capacitive effect at low frequencies. If it is possible to arrange for the elements to be in the right propportions, i.e. if G/C = R/L, the cable velocity will be constant with frequency. There will still be loss, however, but the cable will not distort a complex waveform as it passes down the cable. In practical cables, this often means loading down the cable with shunt conductances and increasing the cable losses greatly. In real cables, losses increase greatly with frequency. Furthermore, the conductors are subject to the skin effect making the effective series resistance increase with frequency. Likewise the capacitance, which is a function of the dielectric constant of the insulator, also changes with frequency. [The term dielectric constant is a poor one. It is hardly constant being a strong function of temperature and frequency in virtually all materials.] The result is that the assumption of a lossless, constant characteristic impedance cable is a poor one if operation is expected over a broad frequency range. Jim also wrote: > Refer to the formulas for Zo of parallel or coaxial lines > (Zo= 276 Log 2S/d where S is center to center distance > between the conducior and d is diameter of conductor[same > units], Zo= 138 log (b/a) where b is inside diameter of > outer conductor and a is outside diameter of inner > conductor. In the case of parallel transmission lines, the above equation is only an approximation. A more accurate equation is: Zo = 120 arc-hyperbolic-cosine(S/d) and this applies only for vacuum insulated lines (since the dielectric constant of air is approximately unity, it works for air too). For example when the spacing is 1.5 times the conductor diameter, Jim's equation predicts the characteristic impedance to be 14 percent too high, and it gets worse with even closer spacing. 73, Dr. Barry L. Ornitz WA4VZQ ornitz@tricon.net P.S. A good website to visit is: http://www.st-andrews.ac.uk/~www_pa/Scots_Guide/audio/part7/page1.html From jimr.reid@verizon.net Sat May 10 05:28:27 2003 From: jimr.reid@verizon.net (Jim Reid) Date: Fri, 9 May 2003 18:28:27 -1000 Subject: [Antennas] Complex Characteristic Impedance of Cables References: <20030509055603.3E88A3289DC@mailman.qth.net> <001801c3168d$b51bbe80$4b5b62d8@naxs.com> Message-ID: <000a01c316ac$aa406a00$923e4104@NewOne> Ok, down to "basics". What is "reactance"? I don't mean all the engineering and mathmatical tools and concepts we use to "deal" with reactance; I mean: what is it? Consider potential and kinetic energy. I believe that a system or component, when operating as intended, is a good "pipe" for kinetic energy to flow through. Now, reactance is some sort of conveter; a converter which somehow detours good, useful kinetic energy off into a resovoir of potential energy. That is, energy has been put into the "system" to accomplish some purpose, but some of it is sidetracked; when sidetracked we have tools to deal with it. All of that is involved in the business of reactance, matching, resonating, etc., etc. In our radio "systems", where we have tools which talk about capacitance and inductance, these are just words to describe the characteristic of the resovoirs in which our useful kinetic energy gets trapped: (1) in an electrical field which is going nowhere, and doing nothing useful -- we call that "capacitive reactance" or negative jX. (2) If our energy is trapped into a potential energy resovoir of a magnetic field -- we call that "inductive reactance", or positive jX. Well, I propose going no further with this. I am in sort of a funk tonight! My new radio has not yet been shipped to me, and I have wandered off into pity land, hi. So I found your thread about Zo a useful place to toss out some discussion fodder; fodder whose resolution will accomplish no useful purpose whatsoever. But, it is a release for my frustration this Friday late evening. Just delete this thing and forget it; it has already served my purpose. 73, Jim KH7M On a continuing wet and rainy May evening on Kauai to which the propagation is lousy! From ornitz@tricon.net Sat May 10 06:46:46 2003 From: ornitz@tricon.net (Barry L. Ornitz) Date: Sat, 10 May 2003 01:46:46 -0400 Subject: [Antennas] Complex Transmission Line Impedance Message-ID: <008d01c316b7$8c5039c0$5a5b62d8@naxs.com> I agree fully with George's comments: > Jim, you seem to prefer keeping this discussion on the ] > reflector when your objections properly belong in a private > forum. However, that is your choice. . . > > Let me be as brief as I can. > You have chosen to view a very complex subject through the > convenient knothole of "typical amateur radio HF" practices. > Consequently, you have reached conclusions which while they > work well enough in that area, are NOT generally true, and > neither Wes nor I are in error for pointing this out to > you. Earlier George had written: >> 2. depending upon the frequency range involved, the >> reactive component Xo of Zo may or may not be of >> importance. And Jim replied: > *****DEFINITELY******** Especially when the frequency range > is within the normal range for the particular transmission > lines application (where line losses are tolerable) This clearly shows he still does not understand and is trying to pick bits and pieces of information out of context from accepted texts. Actually transmission lines show the most complex characteristic impedance effects at low frequencies - where their losses are the lowest. At such frequencies, the dielectrics are nearly perfect (polyethylene and polytetrafluoroethylene have negligible losses at such frequencies). Likewise below the frequency where the inner conductor diameter is the same as the skin depth, the series resistance is the least. I discovered the reality of a complex characteristic impedance several years ago in a particular instrumentation problem I was working on. I was trying to measure extreme high frequency mechanical vibration on a piece of equipment located in a hazardous area (explosive vapors). I was using a 100 ohm half-bridge strain gage to measure the mechanical deflection of the equipment. Thus my output signal (millivolts) came from an essentially 50 ohm resistive source. In the lab, I was easily able to measure signals on a FFT spectrum analyzer up to several hundred kilohertz with a mock- up of the mechanical system. Because of the explosive environment, my strain gage was connected by several hundred feet of 50 ohm, double shielded coaxial cable to the analyzer in a safe location. Power to the bridge came from an intrinsically safe supply. Double shielding was used to minimize noise pickup on the low level signals. In retrospect, shielded twisted pair with a full bridge gage might have been a better choice. Cable losses at these frequencies should have been a small fraction of a decibel, yet I saw great differences in the spectrum between the lab hookup and the process hookup. It turned out that I had not considered the fact that the cable no longer had a resistive 50 ohm characteristic impedance. Even though the cable length of a few hundred feet was a small fraction of a wavelength, it was enough to cause considerable dispersion in the waveforms and very significant apparent attenuation versus frequency effects. Once I realized what was happening, I calculated the real cable characteristic impedance as a function of frequency and used this to mathematically "deconvolve" the data to get the correct spectra. It matched the lab data perfectly after this. This example shows the importance of a complex characteristic impedance. In fact, any shielded wire at low frequencies shows considerable capacitive effects. Knowing when and where to use the resistive approximation to characteristic impedance is important and well worth discussing here. 73, Barry L. Ornitz WA4VZQ ornitz@tricon.net From mlmiller@charter.net Sat May 10 07:38:21 2003 From: mlmiller@charter.net (Mike Miller) Date: Sat, 10 May 2003 01:38:21 -0500 Subject: [Antennas] measuring SWR Message-ID: <3EBC580D.18643.F338857@localhost> I'm trying to match my 2m copper pipe j-pole to the feed line. When I had it on the ground I could adjust the feed point and get a very low swr across the band. After I put it up I couldn't get a good match at the lower frequencies but could at the high end of the band. This was measured at the transmitter end of the feedline. Now I've changed the feedline length and the apparent swr has changed again. How can I eliminate the transmission line transformer effect while trying to adjust the feed point taps to a 50 Ohm match? Will using a 1/2 wave length line between the swr meter and antenna show me the true swr? TIA Mike KC9DOA From w0opw@arrl.net Sat May 10 13:42:18 2003 From: w0opw@arrl.net (Pat W_) Date: Sat, 10 May 2003 07:42:18 -0500 Subject: [Antennas] measuring SWR Message-ID: A Jpole should require a Balun at the feedpoint due to the unbalanced nature of the feed. Adding feedline to any unbalalnced system will show a change in resonance because the feedline has become part of the antenna!. In fact, a change in resonance when adding feedline is a test for the need for a balun. (Jpoles also show a change in impedance due to the height, but, that will change the SWR when changing the height, not Resonance). Add a current Balun(1:1). Test for resonance at ground level, add some multiple of 1/4 wave of feedline and test for resonance again. If resonance doesn't change then the Balun is working and it's safe to put the antenna up in the air. Pat W0OPW _________________________________________________________________ STOP MORE SPAM with the new MSN 8 and get 2 months FREE* http://join.msn.com/?page=features/junkmail From w4tg@bellsouth.net Sat May 10 14:17:39 2003 From: w4tg@bellsouth.net (Harvey&Bessie) Date: Sat, 10 May 2003 09:17:39 -0400 Subject: [Antennas] measuring SWR References: <3EBC580D.18643.F338857@localhost> Message-ID: <3EBCFBF3.BE2359F2@bellsouth.net> Yes! Provided, of course, the 1/2 wave" transmission line is truly 1/2 wavelength: taking the velocity factor into consideration. Harvey/W4TG From w5yr@att.net Sat May 10 14:17:48 2003 From: w5yr@att.net (George, W5YR) Date: Sat, 10 May 2003 08:17:48 -0500 Subject: [Antennas] Complex Transmission Line Impedance References: <008d01c316b7$8c5039c0$5a5b62d8@naxs.com> Message-ID: <001101c316f6$8e317e40$0401a8c0@PS> Thanks, Barry - your comments and opinion are much appreciated. Your strain-gage experience is interesting. I had a similar experience before retirement at Texas Instruments where I was responsible for all of our worldwide network (our private Internet!) performance and availability of service. One problem involved our IMS terminals which were connected to central controllers via shielded twisted pair. The original system engineers - I use the term loosely - failed to consider that not only did the line function in the manner of a transmission line but that at the frequencies involved, its Zo was considerably reactive, thereby doing a wondrous dispersion job on the packet pulses. With thousands of such terminals in the system, replacing the distribution system and/or modifying the terminal circuitry was out of the question. So, I took the easy way out and just swamped the terminal input connection with an appropriate resistor to more or less terminate the line. This reduced the errors due to multiple reflected pulses. We had to live with the dispersion but the data rates were sufficiently low that this could be tolerated. I hope that we can terminate this discussion soon before it hatches the other seasonal jousts such as the *real* direction of "current" flow and the *real* difference between "voltage decibels" and "current decibels." My apologies to the list if my last response to Jim seemed to lack my usual positive outlook and overall good humor approach. And for the record, there are many references in the ARRL Antenna Book, for example, to complex characteristic impedance, including one HF amateur example where it is involved in the solution of the problem. 73/72, George Amateur Radio W5YR - the Yellow Rose of Texas Fairview, TX 30 mi NE of Dallas in Collin county EM13QE "In the 57th year and it just keeps getting better!" ----- Original Message ----- From: "Barry L. Ornitz" To: Cc: ; ; Sent: Saturday, May 10, 2003 12:46 AM Subject: [Antennas] Complex Transmission Line Impedance > I agree fully with George's comments: > > > Jim, you seem to prefer keeping this discussion on the ] > > reflector when your objections properly belong in a private > > forum. However, that is your choice. . . > > > > Let me be as brief as I can. > > > You have chosen to view a very complex subject through the > > convenient knothole of "typical amateur radio HF" practices. > > Consequently, you have reached conclusions which while they > > work well enough in that area, are NOT generally true, and > > neither Wes nor I are in error for pointing this out to > > you. > > Earlier George had written: > > >> 2. depending upon the frequency range involved, the > >> reactive component Xo of Zo may or may not be of > >> importance. > > And Jim replied: > > > *****DEFINITELY******** Especially when the frequency range > > is within the normal range for the particular transmission > > lines application (where line losses are tolerable) > > This clearly shows he still does not understand and is trying > to pick bits and pieces of information out of context from > accepted texts. > > Actually transmission lines show the most complex > characteristic impedance effects at low frequencies - where > their losses are the lowest. At such frequencies, the > dielectrics are nearly perfect (polyethylene and > polytetrafluoroethylene have negligible losses at such > frequencies). Likewise below the frequency where the inner > conductor diameter is the same as the skin depth, the series > resistance is the least. > > I discovered the reality of a complex characteristic impedance > several years ago in a particular instrumentation problem I > was working on. I was trying to measure extreme high > frequency mechanical vibration on a piece of equipment located > in a hazardous area (explosive vapors). I was using a 100 ohm > half-bridge strain gage to measure the mechanical deflection > of the equipment. Thus my output signal (millivolts) came > from an essentially 50 ohm resistive source. > > In the lab, I was easily able to measure signals on a FFT > spectrum analyzer up to several hundred kilohertz with a mock- > up of the mechanical system. Because of the explosive > environment, my strain gage was connected by several hundred > feet of 50 ohm, double shielded coaxial cable to the analyzer > in a safe location. Power to the bridge came from an > intrinsically safe supply. Double shielding was used to > minimize noise pickup on the low level signals. In > retrospect, shielded twisted pair with a full bridge gage > might have been a better choice. > > Cable losses at these frequencies should have been a small > fraction of a decibel, yet I saw great differences in the > spectrum between the lab hookup and the process hookup. > > It turned out that I had not considered the fact that the > cable no longer had a resistive 50 ohm characteristic > impedance. Even though the cable length of a few hundred feet > was a small fraction of a wavelength, it was enough to cause > considerable dispersion in the waveforms and very significant > apparent attenuation versus frequency effects. > > Once I realized what was happening, I calculated the real > cable characteristic impedance as a function of frequency and > used this to mathematically "deconvolve" the data to get the > correct spectra. It matched the lab data perfectly after > this. > > This example shows the importance of a complex characteristic > impedance. In fact, any shielded wire at low frequencies > shows considerable capacitive effects. Knowing when and where > to use the resistive approximation to characteristic impedance > is important and well worth discussing here. > > 73, Barry L. Ornitz WA4VZQ ornitz@tricon.net > > - - - > > Your moderator for this list is: > Larry Wilson KE1HZ antennas-owner@mailman.qth.net > _______________________________________________ > Antennas mailing list > Antennas@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/antennas From w5yr@att.net Sat May 10 14:48:18 2003 From: w5yr@att.net (George, W5YR) Date: Sat, 10 May 2003 08:48:18 -0500 Subject: [Antennas] measuring SWR References: <3EBC580D.18643.F338857@localhost> Message-ID: <003b01c316fa$d096e190$0401a8c0@PS> Mike, it appears that you are feeding a balanced load - the 1/4-wave matching section - with unbalanced coax. Unless you use an effective balun at the feedpoint, the outer braid of the coax becomes a radiating portion of the actual antenna. Thus, the feedline length, position, etc. affect the SWR and the actual performance of the antenna. In addition the presence of common-mode current on the outer braid will upset the operation of the SWR meter and May cause it to give erroneous readings. The only way to eliminate the feedline transformer action is to terminate it in its Zo of around 50+j0 ohms. With careful adjust of the tap position on the matching section and an effective balun, you should be able to achieve good operation. You can fiddle with the feedline length, but again without a balun, the outer braid is part of the radiating system so the length will have effects above and beyond merely altering the input impedance of the line. Use whatever feedline length is convenient to reach from the antenna to the rig or tuner, and add a proper balun, and you should obtain satisfactory performance. 73/72, George Amateur Radio W5YR - the Yellow Rose of Texas Fairview, TX 30 mi NE of Dallas in Collin county EM13QE "In the 57th year and it just keeps getting better!" ----- Original Message ----- From: "Mike Miller" To: Sent: Saturday, May 10, 2003 1:38 AM Subject: [Antennas] measuring SWR > I'm trying to match my 2m copper pipe j-pole to the feed line. > When I had it on the ground I could adjust the feed point and > get a very low swr across the band. After I put it up I couldn't > get a good match at the lower frequencies but could at the high > end of the band. This was measured at the transmitter end of the > feedline. Now I've changed the feedline length and the apparent > swr has changed again. > > How can I eliminate the transmission line transformer effect > while trying to adjust the feed point taps to a 50 Ohm match? > Will using a 1/2 wave length line between the swr meter and > antenna show me the true swr? > > TIA > > Mike KC9DOA > - - - > > Your moderator for this list is: > Larry Wilson KE1HZ antennas-owner@mailman.qth.net > _______________________________________________ > Antennas mailing list > Antennas@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/antennas From e.j.forwood@juno.com Sat May 10 17:22:49 2003 From: e.j.forwood@juno.com (e.j.forwood@juno.com) Date: Sat, 10 May 2003 10:22:49 -0600 Subject: [Antennas] measuring SWR Message-ID: <20030510.102251.1376.0.e.j.forwood@juno.com> First question! Are you using an SWR meter that is useable at 144 MHz? Most are only accurate to 30 MHz. unless they are truly designed for VHF use. 73 de Jerry, K�EJF On Sat, 10 May 2003 01:38:21 -0500 "Mike Miller" writes: > I'm trying to match my 2m copper pipe j-pole to the feed line. > When I had it on the ground I could adjust the feed point and > get a very low swr across the band. After I put it up I couldn't > get a good match at the lower frequencies but could at the high > end of the band. This was measured at the transmitter end of the > feedline. Now I've changed the feedline length and the apparent > swr has changed again. > > How can I eliminate the transmission line transformer effect > while trying to adjust the feed point taps to a 50 Ohm match? > Will using a 1/2 wave length line between the swr meter and > antenna show me the true swr? > > TIA > > Mike KC9DOA > - - - > > Your moderator for this list is: > Larry Wilson KE1HZ antennas-owner@mailman.qth.net > _______________________________________________ > Antennas mailing list > Antennas@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/antennas > > E. Jerold (Jerry) Forwood From k0elr@mchsi.com Sat May 10 19:03:45 2003 From: k0elr@mchsi.com (Douglas J. Koehler) Date: Sat, 10 May 2003 13:03:45 -0500 Subject: [Antennas] measuring SWR In-Reply-To: <3EBC580D.18643.F338857@localhost> Message-ID: <5.1.0.14.2.20030510130116.021fc580@mail.mchsi.com> Mike, I've built around a dozen j-poles and variants in the past 10 years and what you've got is an impedance mismatch. Your feedline is 50 ohm unbalanced and your antenna is probably around 300 ohms unbalanced. This impedance mismatch is causing current to flow on the outside of your feedline coax, making it part of the antenna. When you change the length of the feedline, you change the characteristics of the antenna. Now one solution could be to adjust the antenna feedpoint for minimum SWR while the antenna is in the desired mounting location. However, since the feedline is now part of the antenna, the feedline is now radiating RF. This can cause the radiation pattern to behave unpredictably. Another option is to coil the feedline into a small, multi-turn loop (5-6 turns should be enough) near the antenna. This will act as a choke to the RF current on the shield of the coax and will prevent the feedline from becoming part of the antenna. You need to do this when you adjust the antenna and then use the exact same coil when you install the antenna. The downside is, this doesn't really solve the mismatch problem, it just blocks the RF on the outside of the coax from getting back to the feedline. This blocked RF will be converted to heat in the choke, which results in less power to the antenna. A better choice is to correct the mismatch with a balun. Most j-pole designs have a characteristic impedance around 300 ohms. This is 6 times the impedance of the coax and your radio. So a 6:1 balun would be best. But in practice, a 4:1 balun will work well enough you won't notice a difference. The impedance of your antenna can be approximately calculated with the formula: Z = 267*log(2*S/D) where S is the spacing between the elements, center to center D is the diameter of the conductors. You can use either centimeters or inches for this calculation as long as you use the same units for S and D. I've used a 1/2 wavelength section of the same type of coax as the feedline to make a 4:1 impedance transformer. The ARRL handbook has designs for these in the transmission line section. You can also match the impedance with a series-section transformer. I've tried these as well but found that the length of the series sections end up being larger than the 1/2 wave 4:1 balun. These are also covered in the ARRL handbook transmission line section and are a bit more work to design. If you're up to some heavier reading on jpole design, you might want to go to http://snow.prohosting.com/~w0rcy/Jpole/jpole.html and read the article by N3GO. BTW, wherever possible, you should measure the SWR as close to the antenna as you can. Losses in the feedline will make the SWR at the radio measure lower than the actual SWR occurring at the antenna. Good luck & 73 Doug, K0ELR At 01:38 AM 5/10/2003, Mike Miller wrote: >I'm trying to match my 2m copper pipe j-pole to the feed line. >When I had it on the ground I could adjust the feed point and >get a very low swr across the band. After I put it up I couldn't >get a good match at the lower frequencies but could at the high >end of the band. This was measured at the transmitter end of the >feedline. Now I've changed the feedline length and the apparent >swr has changed again. > >How can I eliminate the transmission line transformer effect >while trying to adjust the feed point taps to a 50 Ohm match? >Will using a 1/2 wave length line between the swr meter and >antenna show me the true swr? > >TIA > >Mike KC9DOA >- - - > >Your moderator for this list is: >Larry Wilson KE1HZ antennas-owner@mailman.qth.net >_______________________________________________ >Antennas mailing list >Antennas@mailman.qth.net >http://mailman.qth.net/mailman/listinfo/antennas From mayen1@mwt.net Sat May 10 21:31:44 2003 From: mayen1@mwt.net (Joe Mayenschein) Date: Sat, 10 May 2003 15:31:44 -0500 Subject: [Antennas] measuring SWR References: <5.1.0.14.2.20030510130116.021fc580@mail.mchsi.com> Message-ID: <3EBD61B0.1550F091@mwt.net> "Douglas J. Koehler" wrote: > Mike, > > I've built around a dozen j-poles and variants in the past 10 years and > what you've got is an impedance mismatch. Your feedline is 50 ohm > unbalanced and your antenna is probably around 300 ohms unbalanced. Now I also have built dozens of "J" Poles in my almost 30 years in this hobby, And the above statement is a bit confusing to me, Yes the balanced to un-balanced thing is correct,, BUT,, I beg to differ on the 300 ohm statement,, IIRC the position of the taps determine the antennas impedance. 0 ohms at the base of the stub (connected to the short) and nearly infinite at the end of the stub. or at least several thousand ohms,, and everywhere in-between from 0 to the infinite. That's why they are soo very easy to match.. Joe WB9SBD From mlmiller@charter.net Sat May 10 21:52:43 2003 From: mlmiller@charter.net (Mike Miller) Date: Sat, 10 May 2003 15:52:43 -0500 Subject: [Antennas] measuring SWR In-Reply-To: <5.1.0.14.2.20030510130116.021fc580@mail.mchsi.com> References: <3EBC580D.18643.F338857@localhost> Message-ID: <3EBD204B.18442.1CD20E@localhost> I'd like to thank everyone for their input. I am feeding the antenna with a 4:1 coax balun. The last change I made was to move the antenna approximately 1 foot farther from the side of the my TV tower. This was done when i replaced the angle iron with square tube for better mechanical stability. This also changed the feedline routing. I was able to adjust the tap location so that the swr dips to a very low value at 146.01 and rises to less than 1.5:1 at the lower and upper ends of the FM band plan. It's still not right, but it will do for now. Thanks again, 73 Mike KC9DOA From k0elr@mchsi.com Sat May 10 21:08:02 2003 From: k0elr@mchsi.com (Douglas J. Koehler) Date: Sat, 10 May 2003 15:08:02 -0500 Subject: [Antennas] measuring SWR In-Reply-To: <3EBD61B0.1550F091@mwt.net> References: <5.1.0.14.2.20030510130116.021fc580@mail.mchsi.com> Message-ID: <5.1.0.14.2.20030510145452.0328b100@mail.mchsi.com> I don't claim to be an expert I can only tell you what has worked for me in the past. I've always had the best results building jpoles when I treated the J as a transmission line and made the ratio of conductor diameter to spacing to be around 300 ohms. Yes, in theory, the top of the J is infinite and the bottom is zero. In practice I find that either end comes up a bit short on either end. that's my experience. I just thought I'd offer my experiences with building Jpoles in an attempt to help. After reading your response and 6 others off the list (one of which was quite abusive) I see now I shouldn't have bothered. Obviously your 30 years in amateur radio trumps my 25 years as a paid professional communications technician. I will now shut up and unsubscribe from this list. At 03:31 PM 5/10/2003, Joe Mayenschein wrote: >"Douglas J. Koehler" wrote: > > > Mike, > > > > I've built around a dozen j-poles and variants in the past 10 years and > > what you've got is an impedance mismatch. Your feedline is 50 ohm > > unbalanced and your antenna is probably around 300 ohms unbalanced. > >Now I also have built dozens of "J" Poles in my almost 30 years in this hobby, >And the above statement is a bit confusing to me, > >Yes the balanced to un-balanced thing is correct,, BUT,, I beg to differ >on the >300 ohm statement,, IIRC the position of the taps determine the antennas >impedance. > >0 ohms at the base of the stub (connected to the short) and nearly >infinite at >the end of the stub. or at least several thousand ohms,, > >and everywhere in-between from 0 to the infinite. That's why they are soo >very >easy to match.. > >Joe WB9SBD > > > >- - - > >Your moderator for this list is: >Larry Wilson KE1HZ antennas-owner@mailman.qth.net >_______________________________________________ >Antennas mailing list >Antennas@mailman.qth.net >http://mailman.qth.net/mailman/listinfo/antennas From mayen1@mwt.net Sat May 10 23:55:46 2003 From: mayen1@mwt.net (Joe Mayenschein) Date: Sat, 10 May 2003 17:55:46 -0500 Subject: [Antennas] measuring SWR References: <5.1.0.14.2.20030510130116.021fc580@mail.mchsi.com> <5.1.0.14.2.20030510145452.0328b100@mail.mchsi.com> Message-ID: <3EBD8372.16BC2523@mwt.net> "Douglas J. Koehler" wrote: > I don't claim to be an expert I can only tell you what has worked for me in > the past. I've always had the best results building jpoles when I treated > the J as a transmission line and made the ratio of conductor diameter to > spacing to be around 300 ohms. 1- You NEVER said anything about the 300 ohm as the impedance of the "J" or matching section,, you said that it was the impedance of the antenna. > > > Yes, in theory, the top of the J is infinite and the bottom is zero. In > practice I find that either end comes up a bit short on either end. that's > my experience. And would be very true > > > I just thought I'd offer my experiences with building Jpoles in an attempt > to help. After reading your response and 6 others off the list (one of > which was quite abusive) I see now I shouldn't have bothered. Obviously > your 30 years in amateur radio trumps my 25 years as a paid professional > communications technician. I didn't claim to be a Pro, I was just stating a thought and I even said that I did not understand about the 300 ohm thing. > I will now shut up and unsubscribe from this list. And if a little Misunderstanding like this would make you leave a fine list like this, I'd love to have your "Professional" Job,, because obviously you don't have any type of boss like 99% of the rest of us have if a question like this gets you all pissed off and want to leave. eez! Joe From durwydd@hotmail.com Sun May 11 16:59:57 2003 From: durwydd@hotmail.com (Durwydd MacTara) Date: Sun, 11 May 2003 15:59:57 +0000 Subject: [Antennas] Choices Message-ID: In an attempt to build an ultimate multiband wire antenna, I have constructed a 5/8 wave 80m collinear dipole entirely of open wire feed line. I have three diferent Baluns I can use and all seem to work! #1 is a choke balun made of RG-59 wound on a large ferrite core; #2 is a Palomar Engineers Bead Balun; #3 is a conventional 4:a Balun. Which one to use and why? "Communications" is a People skill, the rest is technology. Durwydd MacTara _________________________________________________________________ Add photos to your messages with MSN 8. Get 2 months FREE*. http://join.msn.com/?page=features/featuredemail From ac5p@juno.com Sun May 11 19:50:12 2003 From: ac5p@juno.com (Mike J Maloney) Date: Sun, 11 May 2003 13:50:12 -0500 Subject: [Antennas] 2M J-Pole Construction? Message-ID: <20030511.135018.-1028221.0.ac5p@juno.com> Question for those who have experience with making several of subject. If the J-pole is made from copper tubing, would it be advantageous to run the coax inside the copper tubing to tap up on the stub? Would 1/4 wave radials work in lieu of a balun or choke coil to futher isolate the feedline? 73, Mike, ac5p From swanman@cfu.net Mon May 12 03:19:16 2003 From: swanman@cfu.net (Jan C. Robbins) Date: Sun, 11 May 2003 21:19:16 -0500 Subject: [Antennas] FS: New-in-box B&W BWD Folded Dipole Message-ID: <3EBF04A4.D5A4C1D1@cfu.net> This is a brand new (purchased 2002), never opened B & W BWD 1.8-30 mhz folded dipole 90' long. Acts like an extended double zepp above 7 mhz. Handles 5kw. One of the most versatile, durable, yet simple and easy to erect all-band antennas ever designed. No doubt that's why more of them--by tens of thousands!--have been sold worldwide than any other antenna ever made, esp. to govt./commercial/military units. I've used them for three decades myself with great success, in both DX and domestic operation. They run $199 from a dealer, but I can sell this one for $125 shipped anywhere lower 48. It'll make someone a really great antenna. tks es 73, jan N0JR From colt@inreach.com Mon May 12 04:56:44 2003 From: colt@inreach.com (J C White) Date: Sun, 11 May 2003 20:56:44 -0700 Subject: [Antennas] J-Poles Message-ID: <007e01c3183a$88437d40$641ffea9@jwhite> I have built J-Poles for about 30 years, using everything from wire inside PVC to copper tubing to TV twin-lead. Three of my antennas are multiband, one is 6 & 2, one is 6 & 2 & 0.7 meters, and one is four banc, 6, 2, 1/12, 3/4, all on single main section. Only the stubs are fed for each band, and vertical spacing causes no significant problems. The 6 & 2 is from an ARRL antenna book, and I just took off from there. A friend has built about 50 J-Poles within the last 5 years, all copper. We both have discovered that only on 6M is there much advantage to running the coax all the way up inside the main section. However, there is nothing to prevent you from running it inside, IF you make certain you do NOT weaken the tubing where the coax exits. As for ground planes, neither of us have found much value in the form of gain from them. Usually all it takes to keep RF off the shield of the coax is a couple of turns of coax taped in a small loop...remember we are talking VHF/UHF here so not much inductance is needed. I HAVE used the ground planes for isolation between the stubs, with some increase in gain, but this is only useful on multiband J-Poles we generally conclude. My 4 band J has the 6M on the bottom and each following band as the next stub up. When I do run the coax inside the main section for more than 2 bands, I go to larger tubine than the 1/2 and 3/4 used in the ARRL book. This allows me to place my RF blocking coils just below the feedpoint for each of the stubs. Be careful about the multiple shields of the coax feedlines all connected to the main section, on multi-band Js.. Though ground loops are far less troublesome at these frequencies, it is something to check on to see if you are getting any ground loop current, even in microamps, measured between shields at the transceiver end of the line. Hope this helps. I think I have the design of the 6 & 2 M dual band J as gif file, and the 6 & 3/4 as well. May even have the 6, 2, 3/4 M J design as a gif. Remember if you go multiband with feedline INSIDE main section, you're using larger diameter tubing is going to change the length of the main sections and the stubs. Most issues of the ARRL Handbook give the correction factor for changes in antenna material diameter (often called "k" factor). Have fun, and check out the "copper cactus" J website. The very simplest J is just a piece of TV twinlead, with the stub part cut short. You can extend the twinlead well below the feed point, if you want to use it as a universal matching stub to nit pick your way to absolute 1:1 SWR (adjust the length of the shorting section). Remember to NOT use steel screws if you are fastening the feedline to the copper with screws, due to electrogalvanic action. Brass hardware is fine. Or, if you must mismatch metals, say for strength of the main section, get a tube of the anti-galvanic paste electricians use when joining aluminum and copper wire or copper and steel wire. WB6BLV@inreach.com From kd5ckp@centurytel.net Mon May 12 12:18:09 2003 From: kd5ckp@centurytel.net (Tim) Date: Mon, 12 May 2003 06:18:09 -0500 Subject: [Antennas] Mobile Opinions Message-ID: <00d201c31878$2b8403c0$0101a8c0@tech1> I have a friend that has a 28' Travel Trailer and he was asking my opinion on antenna options. Being perfectly realistic I have no travel trailer experience and extremely limited mobile HF experience so I figured I would post the question here where experience abounds. I asked him if he wanted quick and dirty portable or mobile operation and his reply was "Mobile." I suggested either one of the many Screwdriver designs or the SGC Tuner and 20 meter option, because both of those seem to be what is popular in this area. You guys may have other ideas that work as well or better and may even be lighter on the pocket(although I don't think that is a major concern of his) Thanks for the opinions and bandwidth. 73 Tim KD5CKP From donkc0gmf@juno.com Mon May 12 22:29:38 2003 From: donkc0gmf@juno.com (Donald R. Riedel) Date: Mon, 12 May 2003 16:29:38 -0500 Subject: [Antennas] Marine Antenna Web site Message-ID: <20030512.162938.-71453.1.DonKC0GMF@juno.com> Hello, Due to a recent collapse of my hard drive, I have had to replace the little beauty. I had a really good U.S. Marines antenna site but lost it in the disaster. Does anyone have that URL? Thank You in advance, Don KC0GMF --- StripMime Report -- processed MIME parts --- multipart/alternative text/plain (text body -- kept) text/html The reason this message is shown is because the post was in HTML or had an attachment. Attachments are not allowed. To learn how to post in Plain-Text go to: http://www.expita.com/nomime.html --- From swanman@cfu.net Tue May 13 17:55:38 2003 From: swanman@cfu.net (Jan C. Robbins) Date: Tue, 13 May 2003 11:55:38 -0500 Subject: [Antennas] FS: 7-Element Triband BigHorn Delta Loop Array Message-ID: <3EC1238A.915970C3@cfu.net> I recently had occasion to acquire a number of Bob Hobert's (KA1UJ, now deceased) "BigHorn" 10-15-20m 7-element Delta Loop arrays, long out of production. These are simply the best delta loop antennas ever built--72lbs, doubly reinforced boom, all machined parts (no castings), etc. etc. I now have one more than I need, and it's boxed (four large boxes) and ready to ship. Only the 10m parts of this antenna have been used; all else is as new. The antenna is complete and ready to assemble, with documentation. I have used these antennas for more than 15 years, mostly to finish 5BWAZ, and I can tell you they are band openers and pileup busters. Like all apex-down, bottom-fed loops they give very good lower radiation even when mounted low (50-70' is the most you want for these antennas) and will outdo full-size 3- and 4-element monoband yagis up to 70'-90'. I can sell the one I don't need for $595 shipped (they originally cost nearly $900 20 years ago!), so if you can use it pse let me know. It'll knock your socks off. Tks es vy 73! jan N0JR From wd6fgb@infostations.com Tue May 13 18:47:31 2003 From: wd6fgb@infostations.com (Van van Bergen) Date: Tue, 13 May 2003 10:47:31 -0700 Subject: [Antennas] WTB Master Mobil Coils 40/75/80 m Message-ID: <003f01c31977$bf00d010$ec265142@FRED> Subject pretty well says it. Looking for Master Mobil Coils for 40, 75, 80, Meters. Please state condition and price. Thanks Van WD6FGB From durwydd@hotmail.com Wed May 14 16:15:50 2003 From: durwydd@hotmail.com (Durwydd MacTara) Date: Wed, 14 May 2003 15:15:50 +0000 Subject: [Antennas] Input Needed Message-ID: In an attempt to build the ultimate Multiband DX Antenna, I need to make a decision on which Balun to use. My biggest concern is efficiency because I want DXCC QRP! The Atenna in question is a Colinear Dipole made entirely of open wire feed line, 80 feet in the air. By using the open wire for the elements of the Dipole, the arms need only be 42 feet apiece. I have three different Baluns available and all seem to work! Balun #1 is a Standard Torroidal 4:1. Balun #2 is a "Choke Balun of 12 turns of RG-59 on a T-200 Core, Balun #3 is an AMIDON Bead Balun on a length of RG-213. Which one shoul I use and why? Please respond; this is my SECOND attempt on this reflector with zero useful response the first time. "Communications" is a People skill, the rest is technology. Durwydd MacTara _________________________________________________________________ MSN 8 helps eliminate e-mail viruses. Get 2 months FREE*. http://join.msn.com/?page=features/virus From Palomar@compuserve.com Thu May 15 06:32:38 2003 From: Palomar@compuserve.com (Palomar Engineers) Date: Thu, 15 May 2003 01:32:38 -0400 Subject: [Antennas] Input needed Message-ID: <200305150132_MC3-1-38E7-459E@compuserve.com> Use the bead balun. It has no signal loss at all. The other two baluns ma= y be very low loss but they will have some. Your signal does not go through= the bead balun; it has no effect on the signal within the cable. -- Jack,= K6NY, Palomar Engineers From Punkymcd@pacbell.net Thu May 15 15:46:55 2003 From: Punkymcd@pacbell.net (Punkymcd@pacbell.net) Date: Thu, 15 May 2003 07:46:55 -0700 Subject: [Antennas] WTB Ant tuner Message-ID: <3EC3A85F.2060006@pacbell.net> Looking for a NORCAL BLT built or not and a LDG AT-11 or the kit equivalent. De Don, W6OA From rhowes@greenapple.com Tue May 20 09:56:53 2003 From: rhowes@greenapple.com (ralph) Date: Tue, 20 May 2003 04:56:53 -0400 Subject: [Antennas] Input needed References: <200305150132_MC3-1-38E7-459E@compuserve.com> Message-ID: <001601c31ead$c2b62bc0$d64e90c6@den> I bought a Hustler mount so that I can mount 3 antenna's on aa single plate. I notice that the studs have a machined end on them, looks like a 50ohm balun on a computer network. Can anyone tell me why they are made this way?? Do they do a special job?? Thanks in advance for your help. Raph Howes W8BVH From oz1bxn@qsl.net Tue May 20 11:17:03 2003 From: oz1bxn@qsl.net (Chris Jensen) Date: 20 May 2003 12:17:03 +0200 Subject: [Antennas] Velocity factor for wire? Message-ID: <1053425822.2593.31.camel@hack.freedom.dk> Hi All I am looking for the approx velocity factor for 1.5 mm solid Cu.wire , it is insulated with clear paint ( same type being used in a 230 to 18volt mains transformer) What kind of wire and size is Orr using in his book, all about cubical quad? When I design the loops after his Formula 1004/f , I get using my cubber wire a somehow lower resonance frequency , than center of band. best vy73 de oz1bxn chris From w9dmk@crosslink.net Tue May 20 15:26:58 2003 From: w9dmk@crosslink.net (Robert Lay) Date: Tue, 20 May 2003 10:26:58 -0400 Subject: [Antennas] Velocity factor for wire? References: <1053425822.2593.31.camel@hack.freedom.dk> Message-ID: <001d01c31edb$fdcce2c0$59a4c7cf@monster> Dear Chris, You already have all of the information that you need to calculate the Vf exactly. In fact, your calcualtions will be far better than anyone else's guess. Just remember that the theoretical speed of light is around 300000000 m/sec. Measure the length of the wire; calculate the theretical resonant frequency; measure the actual frequency of resonance, and voila', you have the Vf from the formula: Vf = F(resonance, thoretical) / F(resonance, actual) Bob Lay in Dahlgren, VA http://www.qsl.net/w9dmk From w4tg@bellsouth.net Tue May 20 18:05:13 2003 From: w4tg@bellsouth.net (Harvey&Bessie) Date: Tue, 20 May 2003 13:05:13 -0400 Subject: [Antennas] Velocity factor for wire? References: <1053425822.2593.31.camel@hack.freedom.dk> Message-ID: <3ECA6049.9916B5D7@bellsouth.net> Paint or enamel coatings on antenna wires have very little affect upon the velocity factor when these wires are used as antenna wires (strung in air) because the field is not confined within the coating, but extends outward many wire diameters. Harvey/W4TG From mstump@hvc.rr.com Tue May 20 19:57:09 2003 From: mstump@hvc.rr.com (Merv Stump) Date: Tue, 20 May 2003 14:57:09 -0400 Subject: [Antennas] Velocity factor for wire? In-Reply-To: <1053425822.2593.31.camel@hack.freedom.dk> Message-ID: <000d01c31f01$9f80e9c0$b25ea118@Merv> Chris, I doubt that you will find a velocity factor for wire which is general enough and accurate enough to be of much help. However, keep in mind the following: 1. The formula for calculating a half-wave length is 492/fMHz. However the formula we use for calculating the length of a half-wave antenna is 468/fMHz. 468/492 is .95. Some of this differential is due to "end effect" but most is due to the velocity factor. So one might say (with some reservations) that the velocity factor of wire is .95. Now comes the "howevers" 2. The formula for calculating the length of a full-wave length is 984/fMHz, however as Orr and many others have documented full-wave loops are electrically short so the formula we use for calculating the length of a full-wave loop antenna is 1005/fMHz. 3. One more "however" - insulated wire is electrically long by from 1 to 3 percent. Bottom line - when using insulated wire for an antenna I use the appropriate formula and then reduce the length by 2%. All of which is why God made wire cutters and soldering irons, as well as modeling programs. Merv, W2OE From n4sl@yahoo.com Tue May 20 20:02:24 2003 From: n4sl@yahoo.com (Steve L.) Date: Tue, 20 May 2003 12:02:24 -0700 (PDT) Subject: [Antennas] Velocity factor for wire? In-Reply-To: <000d01c31f01$9f80e9c0$b25ea118@Merv> Message-ID: <20030520190224.56597.qmail@web40803.mail.yahoo.com> The real question is this; how high is your quad? What immediately surrounds it? I have found the loop will shift lower in frequency when it couples to objects and/or ground nearby. Is it low to the ground? Near a roof? __________________________________ Do you Yahoo!? The New Yahoo! Search - Faster. Easier. Bingo. http://search.yahoo.com From w7ts@attbi.com Tue May 20 21:57:12 2003 From: w7ts@attbi.com (Ken Kinyon - W7TS) Date: Tue, 20 May 2003 13:57:12 -0700 Subject: [Antennas] Small mobile antennas. In-Reply-To: <011b01c31ef3$2f79bf20$db81030a@internet> Message-ID: <006101c31f12$63941f70$a800a8c0@Kens> I am about to buy a mobile antenna and am considering the high sierra Sidekick and the Little Tar heel. I would appreciate any feedback on either of these. I would also like to know the price of the Sidekick as it is not on their website and they cannot be contacted until Thursday. Thanks in advance, Ken W7TS ------------------- Kenneth E. Kinyon 34 Princeton Circle Longmont, CO 80503-2106 Voice: (303) 684-0037 Fax: (303) 776-5088 E-mail: W7TS@attbi.com W7TS@qsl.net W7TS@arrl.net ALPCA #8339 ARRL-LM ------------------- From davew9lya@juno.com Tue May 20 23:30:10 2003 From: davew9lya@juno.com (David W Sher) Date: Tue, 20 May 2003 17:30:10 -0500 Subject: [Antennas] Velocity factor for wire? Message-ID: <20030520.175636.-4016331.0.davew9lya@juno.com> Work ethic alike Carpenter, tailor, mohel Measure twice, cut once! Dave W9LYA What wrought doG hath? On Tue, 20 May 2003 14:57:09 -0400 "Merv Stump" writes: > Chris, I doubt that you will find a velocity factor for wire which > is > general enough and accurate enough to be of much help. However, > keep in > mind the following: > > 1. The formula for calculating a half-wave length is 492/fMHz. > However > the formula we use for calculating the length of a half-wave antenna > is > 468/fMHz. 468/492 is .95. Some of this differential is due to > "end > effect" but most is due to the velocity factor. So one might say > (with > some reservations) that the velocity factor of wire is .95. > > Now comes the "howevers" > > 2. The formula for calculating the length of a full-wave length is > 984/fMHz, however as Orr and many others have documented full-wave > loops > are electrically short so the formula we use for calculating the > length > of a full-wave loop antenna is 1005/fMHz. > > 3. One more "however" - insulated wire is electrically long by from > 1 > to 3 percent. Bottom line - when using insulated wire for an > antenna I > use the appropriate formula and then reduce the length by 2%. > > All of which is why God made wire cutters and soldering irons, as > well > as modeling programs. > > Merv, W2OE > > > - - - > > Your moderator for this list is: > Larry Wilson KE1HZ antennas-owner@mailman.qth.net > _______________________________________________ > Antennas mailing list > Antennas@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/antennas > > From AG5Q@attbi.com Thu May 22 02:18:34 2003 From: AG5Q@attbi.com (Bob - AG5Q) Date: Wed, 21 May 2003 20:18:34 -0500 Subject: [Antennas] Charge build-up on antennas References: <000d01c31f01$9f80e9c0$b25ea118@Merv> Message-ID: <005a01c32000$10e77940$d184ed0c@attbi.com> During a rainstorm, how fast does charge build up on an antenna? I suppose the area of the wires and tubing would affect this, as well as the amount of rain and wind. I'm wondering if a large resistor across the antenna connector (say, 10K to 100K) would be able to discharge an antenna that is not connected to a rig or is a much smaller resistance required (like a short circuit) to limit the voltage to no more than a few volts. I'm assuming just an ordinary rain storm and neglecting the effect of lightning in the area. Several years ago I noticed enough charge building up on a 20 meter dipole to jump across a small air gap of a ground switch that wasn't closed completely. This occured during a light rain storm. However, I didn't take any quantitative data at the time. There is a potential hazard to a rig if you connected an antenna without shorting the connector terminals first, but would it be enough to just put a resistor across the connector? 73/ Bob - AG5Q From richard@karlquist.com Thu May 22 05:59:24 2003 From: richard@karlquist.com (Richard Karlquist) Date: Wed, 21 May 2003 21:59:24 -0700 Subject: [Antennas] Charge build-up on antennas In-Reply-To: <005a01c32000$10e77940$d184ed0c@attbi.com> Message-ID: My 90 foot vertical is able to drive a voltmeter to 30V and the voltmeter's input impedance is 10 Meg, so the current is 3 uA. Without the voltmeter loading the vertical, I could draw 1/2 inch sparks to ground. Rick N6RK > -----Original Message----- > From: antennas-admin@mailman.qth.net > [mailto:antennas-admin@mailman.qth.net]On Behalf Of Bob - AG5Q > Sent: Wednesday, May 21, 2003 6:19 PM > To: antennas@mailman.qth.net > Subject: [Antennas] Charge build-up on antennas > > > During a rainstorm, how fast does charge build up on an antenna? > I suppose the area of the wires and tubing would affect this, as > well as the amount of rain and wind. I'm wondering if a large > resistor across the antenna connector (say, 10K to 100K) would be able > to discharge an antenna that is not connected to a rig or is a > much smaller resistance required (like a short circuit) to limit the > voltage to no more than a few volts. > > I'm assuming just an ordinary rain storm and neglecting the > effect of lightning in the area. > Several years ago I noticed enough charge building up on a 20 > meter dipole to jump across a small air gap of a ground switch that > wasn't closed completely. This occured during a light rain > storm. However, I didn't take any quantitative data at the time. > > There is a potential hazard to a rig if you connected an antenna > without shorting the connector terminals first, but would it be > enough to just put a resistor across the connector? > > 73/ Bob - AG5Q > > > > > - - - > > Your moderator for this list is: > Larry Wilson KE1HZ antennas-owner@mailman.qth.net > _______________________________________________ > Antennas mailing list > Antennas@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/antennas > From Punkymcd@pacbell.net Thu May 22 23:49:56 2003 From: Punkymcd@pacbell.net (Punkymcd@pacbell.net) Date: Thu, 22 May 2003 15:49:56 -0700 Subject: [Antennas] Super Tee antenna tuner balun Message-ID: <3ECD5414.3050703@pacbell.net> Where can I get the balun called out for the Super Tee? It calls for a BLN-43-202. Can't seem to locate it at either Palomar or Amidon. Or do any of you have one you'd like to part with? Tnx es 73, Don, W6OA From jimsim@adelphia.net Thu May 22 23:57:13 2003 From: jimsim@adelphia.net (Jim Simmons) Date: Thu, 22 May 2003 18:57:13 -0400 Subject: [Antennas] Coax Question's References: <20030402.193211.-3941403.28.davew9lya@juno.com> Message-ID: <004001c320b5$7c456d40$4bb93418@rhmdky.adelphia.net> Hello to all of you, I have a few questions and would appreciate your input! Which of the RG-58's do you consider the best to use for HF transmission? Total cable length is 25ft. Which coax cable would be best to use with a roof mounted, base loaded, vertical antenna? Where would be the best place to buy cable and have it shipped to you? Jim From durwydd@hotmail.com Fri May 23 01:00:59 2003 From: durwydd@hotmail.com (Durwydd MacTara) Date: Fri, 23 May 2003 00:00:59 +0000 Subject: [Antennas] Super Tee antenna tuner balun Message-ID: Don, If you can find the specs, you can "roll your own," other wise you can buy a standard Balun with the proper ratio from thewireman.com. What Bands/Power levels do you need? What sort of feeds/antennas are you trying to match? "Communications" is a People skill, the rest is technology. Durwydd MacTara >From: Punkymcd@pacbell.net >To: antennas@mailman.qth.net >Subject: [Antennas] Super Tee antenna tuner balun >Date: Thu, 22 May 2003 15:49:56 -0700 > >Where can I get the balun called out for the >Super Tee? It calls for a BLN-43-202. Can't seem >to locate it at either Palomar or Amidon. Or do >any of you have one you'd like to part with? > >Tnx es 73, Don, W6OA > >- - - > >Your moderator for this list is: >Larry Wilson KE1HZ antennas-owner@mailman.qth.net >_______________________________________________ >Antennas mailing list >Antennas@mailman.qth.net >http://mailman.qth.net/mailman/listinfo/antennas _________________________________________________________________ MSN 8 helps eliminate e-mail viruses. Get 2 months FREE*. http://join.msn.com/?page=features/virus From ernie@netvision.net.il Fri May 23 06:48:54 2003 From: ernie@netvision.net.il (TL) Date: Fri, 23 May 2003 08:48:54 +0300 Subject: [Antennas] 2 KW pep HF tuner References: <20030402.193211.-3941403.28.davew9lya@juno.com> <004001c320b5$7c456d40$4bb93418@rhmdky.adelphia.net> Message-ID: <009701c320ee$fef748b0$9a44ebd4@ernie> Hello Can anyone point me to a proven design for a homebrew H.F antenna tuner rated for 2 KW P.E.P ? Thanks in advance, Isaac, 4Z4TL http://www.iarc.org/~4z4tl/ ernie@netvision.net.il 4z4tl@iarc.org From W1GOR@Maine.RR.Com Fri May 23 07:17:50 2003 From: W1GOR@Maine.RR.Com (W1GOR) Date: Fri, 23 May 2003 02:17:50 -0400 Subject: [Antennas] Painting Fiberglass Antenna Radomes References: <1053425822.2593.31.camel@hack.freedom.dk> Message-ID: <010d01c320f3$0f8f57e0$8bd7c618@maine.rr.com> For those who asked about painting fiberglass antenna radomes, please go to the following URL... http://www.repeater-builder.com/pdf/antennapainting.pdf 73, Larry - W1GOR From jimsim@adelphia.net Fri May 23 12:45:04 2003 From: jimsim@adelphia.net (Jim Simmons) Date: Fri, 23 May 2003 07:45:04 -0400 Subject: [Antennas] Coax Question's References: <20030402.193211.-3941403.28.davew9lya@juno.com> <004001c320b5$7c456d40$4bb93418@rhmdky.adelphia.net> Message-ID: <007501c32120$c0ac6720$4bb93418@rhmdky.adelphia.net> Time to update the question; When I asked which was best, I meant best over all. The cable will outside subject to weather, but will have no stress/load on it. It will be completely supported. Max power will not be over 300 amps, normally it should be much less. I am one of those "use the least power guys". I do have a SB-200 that I bought and build about 25 yrs ago, I sometimes run it into a dummy load just to check it out. If I every use it, I will use a long wire. After reading all the reply comments, I think that I will go with RG-8x. What do you think? Jim ----- Original Message ----- From: "Jim Simmons" To: Sent: Thursday, May 22, 2003 6:57 PM Subject: [Antennas] Coax Question's > Hello to all of you, > > I have a few questions and would appreciate your input! > > Which of the RG-58's do you consider the best to use for HF transmission? > Total cable length is 25ft. > > Which coax cable would be best to use with a roof mounted, base loaded, > vertical antenna? > > Where would be the best place to buy cable and have it shipped to you? > > Jim > > - - - > > Your moderator for this list is: > Larry Wilson KE1HZ antennas-owner@mailman.qth.net > _______________________________________________ > Antennas mailing list > Antennas@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/antennas From w4foa@comcast.net Fri May 23 13:23:48 2003 From: w4foa@comcast.net (Tony Martin) Date: Fri, 23 May 2003 08:23:48 -0400 Subject: [Antennas] Coax Question's In-Reply-To: <007501c32120$c0ac6720$4bb93418@rhmdky.adelphia.net> Message-ID: Jim, For the situation you describe, I think RG8X would be just ideal. As for "where to buy it"...I guess that depends on where you are located since it sounds like shipping costs will be involved. At the risk of sounding like a commercial, for years I have bought all of my coax from the company in South Carolina, owned by "Pres". I'll be glad to give you more detailed info via private email if you wish. Good luck....the SB200 will be a very nice to have item now that the propogation is so very poor. Keep us posted... 73 Tony, W4FOA Chickamauga, GA Watch your thoughts; they become words. Watch your words; they become actions. Watch your actions; they become habits. Watch your habits; they become character. Watch your character; it becomes your destiny. -Frank Outlaw -----Original Message----- From: antennas-admin@mailman.qth.net [mailto:antennas-admin@mailman.qth.net]On Behalf Of Jim Simmons Sent: Friday, May 23, 2003 7:45 AM To: antennas@mailman.qth.net Subject: Re: [Antennas] Coax Question's Time to update the question; When I asked which was best, I meant best over all. The cable will outside subject to weather, but will have no stress/load on it. It will be completely supported. Max power will not be over 300 amps, normally it should be much less. I am one of those "use the least power guys". I do have a SB-200 that I bought and build about 25 yrs ago, I sometimes run it into a dummy load just to check it out. If I every use it, I will use a long wire. After reading all the reply comments, I think that I will go with RG-8x. What do you think? Jim ----- Original Message ----- From: "Jim Simmons" To: Sent: Thursday, May 22, 2003 6:57 PM Subject: [Antennas] Coax Question's > Hello to all of you, > > I have a few questions and would appreciate your input! > > Which of the RG-58's do you consider the best to use for HF transmission? > Total cable length is 25ft. > > Which coax cable would be best to use with a roof mounted, base loaded, > vertical antenna? > > Where would be the best place to buy cable and have it shipped to you? > > Jim > > - - - > > Your moderator for this list is: > Larry Wilson KE1HZ antennas-owner@mailman.qth.net > _______________________________________________ > Antennas mailing list > Antennas@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/antennas - - - Your moderator for this list is: Larry Wilson KE1HZ antennas-owner@mailman.qth.net _______________________________________________ Antennas mailing list Antennas@mailman.qth.net http://mailman.qth.net/mailman/listinfo/antennas From kkanalz@gcecisp.com Fri May 23 15:23:33 2003 From: kkanalz@gcecisp.com (Karl) Date: Fri, 23 May 2003 09:23:33 -0500 Subject: [Antennas] Coax Question's References: <20030402.193211.-3941403.28.davew9lya@juno.com> <004001c320b5$7c456d40$4bb93418@rhmdky.adelphia.net> <007501c32120$c0ac6720$4bb93418@rhmdky.adelphia.net> Message-ID: <00c101c32136$e4846ba0$901a0ed0@HamShack> Don't you mean "300 watts", rather than 300 amperes, Jim?\ ----- Original Message ----- From: "Jim Simmons" To: Sent: Friday, May 23, 2003 6:45 AM Subject: Re: [Antennas] Coax Question's > Time to update the question; When I asked which was best, I meant best over > all. The cable will outside subject to weather, but will have no stress/load > on it. It will be completely supported. Max power will not be over 300 amps, > normally it should be much less. I am one of those "use the least power > guys". I do have a SB-200 that I bought and build about 25 yrs ago, I > sometimes run it into a dummy load just to check it out. If I every use it, > I will use a long wire. From aa6dx@pacbell.net Fri May 23 22:53:14 2003 From: aa6dx@pacbell.net (AA6DX) Date: Fri, 23 May 2003 14:53:14 -0700 Subject: [TowerTalk] [Antennas] Painting Fiberglass Antenna Radomes References: <1053425822.2593.31.camel@hack.freedom.dk> <010d01c320f3$0f8f57e0$8bd7c618@maine.rr.com> Message-ID: <007301c32175$b6334750$7662ce3f@desk> Too bad .. that site booogers up .. too many Poop Ups .. my safeguards quarantine it .. shhhhoooooseeeee.... Mark AA6DX ----- Original Message ----- From: "W1GOR" To: ; Sent: Thursday, May 22, 2003 11:17 PM Subject: [TowerTalk] [Antennas] Painting Fiberglass Antenna Radomes > For those who asked about painting fiberglass antenna radomes, please go to > the following URL... > > http://www.repeater-builder.com/pdf/antennapainting.pdf > > 73, Larry - W1GOR > > _______________________________________________ > > See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions and ask for Sherman, W2FLA. > > _______________________________________________ > TowerTalk mailing list > TowerTalk@contesting.com > http://lists.contesting.com/mailman/listinfo/towertalk > From n4sl@yahoo.com Fri May 23 22:57:56 2003 From: n4sl@yahoo.com (Steve L.) Date: Fri, 23 May 2003 14:57:56 -0700 (PDT) Subject: [Antennas] (no subject) Message-ID: <20030523215756.33180.qmail@web40808.mail.yahoo.com> > For those who asked about painting fiberglass antenna radomes, please go to > http://www.repeater-builder.com/pdf/antennapainting.pdf Yes, my network firewall would not allow me to access it either. Steve N4SL __________________________________ Do you Yahoo!? The New Yahoo! Search - Faster. Easier. Bingo. http://search.yahoo.com From aa6dx@pacbell.net Sat May 24 00:00:22 2003 From: aa6dx@pacbell.net (AA6DX) Date: Fri, 23 May 2003 16:00:22 -0700 Subject: [TowerTalk] [Antennas] Painting Fiberglass Antenna Radomes References: <1053425822.2593.31.camel@hack.freedom.dk> <010d01c320f3$0f8f57e0$8bd7c618@maine.rr.com> <007301c32175$b6334750$7662ce3f@desk> <014601c3217d$7334bad0$c400a8c0@us2s06tm2xx55u> Message-ID: <008001c3217f$170cbda0$7662ce3f@desk> Hmmm .. gonna have to try it again .. perhaps my main brain is "cooked" --- or, you don't have any popup blocker, etc. there Jim! It is just VERY possible I have some "saviour" program, that is causing this prob .. SILLY ME! As to ACROBAT . I HAVE THE ENTIRE program, latest-greatest, ADOBE ACROBAT 5.XX --- cost a bunch .. ahh,,,,,,, whatta hey .. BTW -- FYI, all. the term .. PDF = "Portable Document File" --- ----- Original Message ----- From: "Jim W7RY" To: "AA6DX" Sent: Friday, May 23, 2003 3:48 PM Subject: Re: [TowerTalk] [Antennas] Painting Fiberglass Antenna Radomes > Its a PDF file... > No popups seen here! > > 73 > Jim W7RY > > ----- Original Message ----- > From: "AA6DX" > To: "W1GOR" ; ; > > Sent: Friday, May 23, 2003 2:53 PM > Subject: Re: [TowerTalk] [Antennas] Painting Fiberglass Antenna Radomes > > > > Too bad .. that site booogers up .. too many Poop Ups .. my safeguards > > quarantine it .. shhhhoooooseeeee.... Mark AA6DX > > ----- Original Message ----- > > From: "W1GOR" > > To: ; > > Sent: Thursday, May 22, 2003 11:17 PM > > Subject: [TowerTalk] [Antennas] Painting Fiberglass Antenna Radomes > > > > > > > For those who asked about painting fiberglass antenna radomes, please go > > to > > > the following URL... > > > > > > http://www.repeater-builder.com/pdf/antennapainting.pdf > > > > > > 73, Larry - W1GOR > > > > > > > > > > > > _______________________________________________ > > > > See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless > Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any > questions and ask for Sherman, W2FLA. > > > > _______________________________________________ > > TowerTalk mailing list > > TowerTalk@contesting.com > > http://lists.contesting.com/mailman/listinfo/towertalk > > > > > > > From W1GOR@Maine.RR.Com Sat May 24 01:41:10 2003 From: W1GOR@Maine.RR.Com (W1GOR) Date: Fri, 23 May 2003 20:41:10 -0400 Subject: [Antennas] Painting Fiberglass Antenna Radomes References: <1053425822.2593.31.camel@hack.freedom.dk> <010d01c320f3$0f8f57e0$8bd7c618@maine.rr.com> <007301c32175$b6334750$7662ce3f@desk> <014601c3217d$7334bad0$c400a8c0@us2s06tm2xx55u> <008001c3217f$170cbda0$7662ce3f@desk> Message-ID: <000c01c3218d$310c4960$8bd7c618@maine.rr.com> I've seen several postings that indicate problems accessing the URL (see below) that contains information about painting antennas. http://www.repeater-builder.com/pdf/antennapainting.pdf If anyone is having trouble accessing that URL, I downloaded the PDF and will forward it to anyone who sends their e-mail address to me... 73, Larry - W1GOR From ornitz@tricon.net Sat May 24 06:46:16 2003 From: ornitz@tricon.net (Barry L. Ornitz) Date: Sat, 24 May 2003 01:46:16 -0400 Subject: [Antennas] Painting Antennas and Fiberglass Spreaders for Quads References: <20030523080147.9BA5F328ACD@mailman.qth.net> Message-ID: <007e01c321b7$ccf13f00$a74562d8@ntelos.net> I should have answered this question a while back but I got caught up in the more interesting discussion on the complex characteristic impedance of coax. Having worked in the research labs of Eastman Chemical, who makes plastics, resins, and solvents used by the paint and varnish industry, and for W. L. Gore & Associates who make true radome material, I think I am well qualified to answer this question. Larry, W1GOT, wrote: > For those who asked about painting fiberglass antenna > radomes, please go to the following URL... > > http://www.repeater-builder.com/pdf/antennapainting.pdf I read these instructions, and there is nothing wrong with them. But they are a little too specific for my taste on what brand of paint to use, and they do not discuss the effect the paint has on the antenna performance at all. Thus, I thought I would fill in some details. To begin, a radome is more properly a structure used to cover a microwave or millimeter wave antenna. Its purpose is to protect the antenna from adverse environments while having an insignificant effect on the electrical performance of the enclosed antenna. Typically radomes are made of glass- reinforced resin plastics (fiberglass) or they may be made of inflated fabric materials (like the PTFE Goretex fabrics). I would not call the protective housing over many commercial VHF antennas a radome. This is because the housing is located in the near-field of the antenna whereas true radomes are in the far field of microwave antennas. A thin layer of paint usually has minimal affect on HF and VHF antennas if the proper paint is chosen [however, the thick fiberglass housing over those VHF antennas often does have an appreciable effect - due to its thickness.] What is happening it that the antenna sees a slightly different dielectric constant in the area surrounding the antenna. Since all real materials have dielectric constants great then unity, the result is that the antenna appears slightly "fatter" than it did bare. Thus the resonant frequency is lowered ever so slightly. You can see this same result when insulated antenna wire is used versus bare wire. For thin coatings (at least compared to the operating wavelength of the antenna) the effect is very small. Recently someone here asked about the reason that a dipole is cut to approximately 95% of its free-space half wavelength. This is almost entirely due to end effects. The so-called velocity factor of an air insulated wire is essentially unity. Adding a thin layer of insulation on the wire only changes this minimally. [For example, to lower the velocity factor of a wire insulated with polyethylene, the poly coating would have to be several wavelengths thick for the velocity factor to approach 0.66.] So assuming the paint is a "low-loss" dielectric material, painting an antenna really changes its performance very little. But what is a "low-loss" dielectric material to paint with? Short answer - most common paints! Long answer - read on... It is really quite difficult to get a truly conductive paint, i.e. one with a surface resistivity of less than a few thousand ohms per square [this is resistivity - not resistance, the measurement is made by measuring the resistance between the two sides of a square of painted material]. Even most metallic paints are pretty good insulators when considered this way. But still it is best to generally avoid metallic paints. What about dielectric losses other than true conductivity? For example, vinyl plastics are far lossier than polyethylene. Again, the important issue is whether the paint is thin and most of the actual insulation is done by air. If so, the added losses of the paint will have minimal effect. Now if the antenna is covered by a relatively thick insulator, like a PVC pipe versus fiberglass shell, you do need to worry about dielectric losses. The real issues when selecting paints for antennas and such are how well does the paint adhere, how does it withstand sunlight (ultraviolet), and how does it withstand weather. Adherence is an issue with both metallic and plastic surfaces. Many paints, particularly water-thinned latex paints, do not wet and adhere to all surfaces well. For metallic surfaces, it is common to acid-etch or treat the metal surface with a primer such as zinc chromate. Usually with slightly oxidized metal, this is not a problem. For plastics with smooth, shiny surfaces, getting adhesion may be a real problem with some paints. Sandpaper may be often be used to roughen the surface to promote adhesion. Commercially, corona discharge surface oxidation is often used to treat plastic surfaces to provide for paint adhesion. Solvent thinned lacquers and oil (or synthetic) based resins usually adhere a little better. They also tend to hold up somewhat better outdoors too. Ultraviolet resistance is the biggest issue with outdoor paints. Acrylic lacquers and enamels actually do quite well in this regard, as do the epoxy and urethane paints. For a small project, ordinary Krylon spray acrylic paints will work quite well. Many manufacturers use carbon-black filled polyethylene caps to seal the ends of traps in their antennas. After a few years, ultraviolet light does its work on the polyethylene. You can see the surface of the plastic become porous and oxidized. At this point, a spray coating of Krylon or equivalent can extend the life of the insulator quite a few years and prevent additional degradation. Plastic insulators on VHF antennas are also good candidates for painting this way. Many oil-based paints "chalk" upon exposure to the elements. This is where the surface of the paint oxidizes and forms a chalky coating. In outdoor house paints, this coating can be scrubbed off to present a clean surface underneath. However this property is not beneficial for antennas as the chalky surface can retain water, dirt and moisture. Modern non- chalking epoxy and urethane paints are much better suited for use here. If I remember correctly, what brought up the question of paint was its use on fiberglass spreaders for cubical quad antennas. From an electrical standpoint, almost any paint could be used here with no measurable change in antenna performance. But one requirement is good flexibility of the cured paint as these spreaders do flex as the wind blows. It may be necessary to sand new fiberglass spreaders to get paint to adhere. Weathered fiberglass needs the paint to prevent moisture ingress of the spreader and to protect the spreader from further weathering. Both epoxy and urethane paints come in air-cured and two-part varieties. The urethane paint recommended in the article Larry pointed to is a two-part type. In practice, the two part types are preferred, but they do have a limited pot life and are more difficult work with. These paints are primarily used in industrial applications so they may be difficult to find in your regular paint stores. Most larger paint manufacturers do make industrial lines that are suitable and these can usually be ordered through your local dealer. As to color, consider that white reflects ultraviolet the best, while black absorbs it best. Either are good choices, although a good titanium dioxide white is my personal choice. As to another personal hint, I usually spray all mounting hardware such as screws and nuts with clear Krylon after an antenna has been assembled. This can provide considerable extra corrosion protection. On larger hardware, I often use some of the "cold galvanizing" paints to spray with. This zinc-loaded paint provides rust protection to steel. So to conclude, the best paints to use on and around HF and VHF antennas are those which provide good adherence, excellent ultraviolet and sunshine protection, and good weathering ability. The electrical properties of the paint are of secondary importance. For real radomes, the issue is much more complex. But then again, I doubt if many of us have real radomes! :-) 73, Dr. Barry L. Ornitz WA4VZQ ornitz@tricon.net From scottsch@ix.netcom.com Sat May 24 08:00:31 2003 From: scottsch@ix.netcom.com (Scott Schappert) Date: Sat, 24 May 2003 00:00:31 -0700 Subject: [Antennas] Anyone need used Discones ? Message-ID: <000b01c321c2$2ae13480$85e2fea9@Moledyne> I have an Icom AH7000 and an AOR DA 3000 I am looking to sell. Both antennas are two years old, have ALL hardware and the element sets are complete. They both have been painted with mil-spec, non-conductive paint to prevent harsh reflections in sunlight. AOR is TNC at the antenna, the Icom is "N" both female. I have moved to LPDA's, specifically, Create models 5130-1 (horizontal plane) and the -2 (vertical plane) and they are phenomenal and compliment each other stacked, won't go back to discones ever. They are not inexpensive, but directional performance and forward gain in the 10-13 dbi area (both models) is a different world. I highly recommend them. If anyone is interested, contact me off the reflector. Asking $150.00 OBO. -Scott Schappert Molecular Inversion Dynamics Engineering Consultant Group scottsch@ix.netcom.com --- StripMime Report -- processed MIME parts --- multipart/alternative text/plain (text body -- kept) text/html The reason this message is shown is because the post was in HTML or had an attachment. Attachments are not allowed. To learn how to post in Plain-Text go to: http://www.expita.com/nomime.html --- From W1GOR@Maine.RR.Com Sat May 24 12:18:41 2003 From: W1GOR@Maine.RR.Com (W1GOR) Date: Sat, 24 May 2003 07:18:41 -0400 Subject: [Antennas] Re: Painting Antennas and Fiberglass Spreaders for Quads References: <20030523080147.9BA5F328ACD@mailman.qth.net> <007e01c321b7$ccf13f00$a74562d8@ntelos.net> Message-ID: <001601c321e6$3fa0bfc0$8bd7c618@maine.rr.com> Barry, Your response, albeit interesting, reminds me of a fellow whom I knew many years ago... He was the type who, when asked, "what time is it..?", would respond with a lengthy lesson on quantum physics and celestial mechanics..., when all I wanted was the correct time...! BTW, the manufacturers of these vertical antennas DO refer to the housings as RADOMES, so that's why the article also used the term RADOME. While your frequent responses are interesting, they tend toward being pedantic and extreme... It would be in the interest of all readers for you to submit simplified responses, and stick to the issue at hand, rather than submitting a professional resume along with your comments... Since my professional credentials are similar to yours, I find that the best response is one that addresses the majority of readers. Also, I'm not into pissing matches, because they bore the hell out of me... besides, I refuse to have a 'battle-of-wits' with unarmed men..! I heard a short story about a little boy who asked his Mom and Dad, "Where did I come from?"... Mom and Dad became flustered, and tried with much stumbling, to explain the 'birds-and-the-bees' to their son... When they were finished with their somewhat embarrassing answer, the little boy said, "Heck, I knew all of that from my sex education class..., but what I want to know is WHERE I came from... Billy is from Philadelphia, John is from Houston and I just want to know WHERE I came from.." and so it goes... 73, Larry - W1GOR ----- Original Message ----- From: "Barry L. Ornitz" To: Cc: Sent: Saturday, May 24, 2003 01:46 Subject: Painting Antennas and Fiberglass Spreaders for Quads > I should have answered this question a while back but I got > caught up in the more interesting discussion on the complex > characteristic impedance of coax. > > Having worked in the research labs of Eastman Chemical, who > makes plastics, resins, and solvents used by the paint and > varnish industry, and for W. L. Gore & Associates who make > true radome material, I think I am well qualified to answer > this question. > > Larry, W1GOT, wrote: (BTW, my call is W1GOR, not W1GOT..!_ > > > For those who asked about painting fiberglass antenna > > radomes, please go to the following URL... > > > > http://www.repeater-builder.com/pdf/antennapainting.pdf > > I read these instructions, and there is nothing wrong with > them. But they are a little too specific for my taste on what > brand of paint to use, and they do not discuss the effect the > paint has on the antenna performance at all. Thus, I thought > I would fill in some details. > > To begin, a radome is more properly a structure used to cover > a microwave or millimeter wave antenna. Its purpose is to > protect the antenna from adverse environments while having an > insignificant effect on the electrical performance of the > enclosed antenna. Typically radomes are made of glass- > reinforced resin plastics (fiberglass) or they may be made of > inflated fabric materials (like the PTFE Goretex fabrics). > > I would not call the protective housing over many commercial > VHF antennas a radome. This is because the housing is located > in the near-field of the antenna whereas true radomes are in > the far field of microwave antennas. > > A thin layer of paint usually has minimal affect on HF and VHF > antennas if the proper paint is chosen [however, the thick > fiberglass housing over those VHF antennas often does have an > appreciable effect - due to its thickness.] What is happening > it that the antenna sees a slightly different dielectric > constant in the area surrounding the antenna. Since all real > materials have dielectric constants great then unity, the > result is that the antenna appears slightly "fatter" than it > did bare. Thus the resonant frequency is lowered ever so > slightly. > > You can see this same result when insulated antenna wire is > used versus bare wire. For thin coatings (at least compared > to the operating wavelength of the antenna) the effect is very > small. Recently someone here asked about the reason that a > dipole is cut to approximately 95% of its free-space half > wavelength. This is almost entirely due to end effects. The > so-called velocity factor of an air insulated wire is > essentially unity. Adding a thin layer of insulation on the > wire only changes this minimally. [For example, to lower the > velocity factor of a wire insulated with polyethylene, the > poly coating would have to be several wavelengths thick for > the velocity factor to approach 0.66.] > > So assuming the paint is a "low-loss" dielectric material, > painting an antenna really changes its performance very little. > > But what is a "low-loss" dielectric material to paint with? > Short answer - most common paints! Long answer - read on... > > It is really quite difficult to get a truly conductive paint, > i.e. one with a surface resistivity of less than a few > thousand ohms per square [this is resistivity - not > resistance, the measurement is made by measuring the > resistance between the two sides of a square of painted > material]. Even most metallic paints are pretty good > insulators when considered this way. But still it is best to > generally avoid metallic paints. > > What about dielectric losses other than true conductivity? > For example, vinyl plastics are far lossier than > polyethylene. Again, the important issue is whether the paint > is thin and most of the actual insulation is done by air. If > so, the added losses of the paint will have minimal effect. > Now if the antenna is covered by a relatively thick insulator, > like a PVC pipe versus fiberglass shell, you do need to worry > about dielectric losses. > > The real issues when selecting paints for antennas and > such are how well does the paint adhere, how does it withstand > sunlight (ultraviolet), and how does it withstand weather. > > Adherence is an issue with both metallic and plastic > surfaces. Many paints, particularly water-thinned latex > paints, do not wet and adhere to all surfaces well. For > metallic surfaces, it is common to acid-etch or treat the > metal surface with a primer such as zinc chromate. Usually > with slightly oxidized metal, this is not a problem. For > plastics with smooth, shiny surfaces, getting adhesion may be > a real problem with some paints. Sandpaper may be often be > used to roughen the surface to promote adhesion. Commercially, > corona discharge surface oxidation is often used to treat > plastic surfaces to provide for paint adhesion. > > Solvent thinned lacquers and oil (or synthetic) based resins > usually adhere a little better. They also tend to hold up > somewhat better outdoors too. > > Ultraviolet resistance is the biggest issue with outdoor > paints. Acrylic lacquers and enamels actually do quite well > in this regard, as do the epoxy and urethane paints. For a > small project, ordinary Krylon spray acrylic paints will work > quite well. Many manufacturers use carbon-black filled > polyethylene caps to seal the ends of traps in their > antennas. After a few years, ultraviolet light does its work > on the polyethylene. You can see the surface of the plastic > become porous and oxidized. At this point, a spray coating of > Krylon or equivalent can extend the life of the insulator > quite a few years and prevent additional degradation. Plastic > insulators on VHF antennas are also good candidates for > painting this way. > > Many oil-based paints "chalk" upon exposure to the elements. > This is where the surface of the paint oxidizes and forms a > chalky coating. In outdoor house paints, this coating can be > scrubbed off to present a clean surface underneath. However > this property is not beneficial for antennas as the chalky > surface can retain water, dirt and moisture. Modern non- > chalking epoxy and urethane paints are much better suited for > use here. > > If I remember correctly, what brought up the question of paint > was its use on fiberglass spreaders for cubical quad > antennas. From an electrical standpoint, almost any paint > could be used here with no measurable change in antenna > performance. But one requirement is good flexibility of the > cured paint as these spreaders do flex as the wind blows. It > may be necessary to sand new fiberglass spreaders to get paint > to adhere. Weathered fiberglass needs the paint to prevent > moisture ingress of the spreader and to protect the spreader > from further weathering. > > Both epoxy and urethane paints come in air-cured and two-part > varieties. The urethane paint recommended in the article > Larry pointed to is a two-part type. In practice, the two > part types are preferred, but they do have a limited pot life > and are more difficult work with. These paints are primarily > used in industrial applications so they may be difficult to > find in your regular paint stores. Most larger paint > manufacturers do make industrial lines that are suitable and > these can usually be ordered through your local dealer. > > As to color, consider that white reflects ultraviolet the > best, while black absorbs it best. Either are good choices, > although a good titanium dioxide white is my personal choice. > > As to another personal hint, I usually spray all mounting > hardware such as screws and nuts with clear Krylon after an > antenna has been assembled. This can provide considerable > extra corrosion protection. On larger hardware, I often use > some of the "cold galvanizing" paints to spray with. This > zinc-loaded paint provides rust protection to steel. > > So to conclude, the best paints to use on and around HF and > VHF antennas are those which provide good adherence, excellent > ultraviolet and sunshine protection, and good weathering > ability. The electrical properties of the paint are of > secondary importance. For real radomes, the issue is much > more complex. But then again, I doubt if many of us have real > radomes! :-) > > 73, Dr. Barry L. Ornitz WA4VZQ ornitz@tricon.net > From baycock@direcway.com Sat May 24 12:46:58 2003 From: baycock@direcway.com (Bill Aycock) Date: Sat, 24 May 2003 06:46:58 -0500 Subject: [Antennas] Re: Painting Antennas and Fiberglass Spreaders for Quads In-Reply-To: <001601c321e6$3fa0bfc0$8bd7c618@maine.rr.com> References: <20030523080147.9BA5F328ACD@mailman.qth.net> <007e01c321b7$ccf13f00$a74562d8@ntelos.net> Message-ID: <5.2.0.9.2.20030524063733.03121d48@pop3.direcway.com> Larry Your attack (yes) was not very productive. I have seen so MUCH crap on this subject that it was good to see someone with real knowledge expound. It WAS needed, to clear up the rumor and folklore that had been spouted.. BTW you need a lesson in netiquette- there was no need to keep ALL of his post as an enclosure to your diatribe. It just adds to the traffic load with no benefit. Bill At 07:18 AM 5/24/2003 -0400, you wrote: >Barry, > >Your response, albeit interesting, reminds me of a fellow whom I knew many >years ago... He was the type who, when asked, "what time is it..?", would >respond with a lengthy lesson on quantum physics and celestial mechanics..., >when all I wanted was the correct time...! Bill Aycock - W4BSG Woodville, Alabama --- StripMime Report -- processed MIME parts --- multipart/alternative text/plain (text body -- kept) text/html The reason this message is shown is because the post was in HTML or had an attachment. Attachments are not allowed. To learn how to post in Plain-Text go to: http://www.expita.com/nomime.html --- From hankarn@pacbell.net Sat May 24 13:32:50 2003 From: hankarn@pacbell.net (hankarn) Date: Sat, 24 May 2003 05:32:50 -0700 Subject: [Antennas] Re: Painting Antennas and Fiberglass Spreaders for Quads References: <20030523080147.9BA5F328ACD@mailman.qth.net> <007e01c321b7$ccf13f00$a74562d8@ntelos.net> <001601c321e6$3fa0bfc0$8bd7c618@maine.rr.com> Message-ID: <000801c321f0$9777bbe0$15acc53f@danhome> Larry, Why not tear into Barry privately as I think his answer covers the subject very well without getting into 3zx/5rf]ddd\=p=resd type of hot air. There is a key on my keyboard with a . and Del and another with the word Delete, I find they work very well in most cases. Carry on Barry and thanks for your input. Hank KN6DI From whitaker@ieee.org Sat May 24 14:15:18 2003 From: whitaker@ieee.org (Cletus W Whitaker) Date: Sat, 24 May 2003 09:15:18 -0400 Subject: [Antennas] Re: Painting Antennas and Fiberglass Spreaders for Quads References: <20030523080147.9BA5F328ACD@mailman.qth.net> <007e01c321b7$ccf13f00$a74562d8@ntelos.net> <001601c321e6$3fa0bfc0$8bd7c618@maine.rr.com> Message-ID: <3ECF7066.9060307@pa.net> de WB2CPN Clete I like Barry's words because I can refer his commentary to other situations. 73 Clete From dufferjames@hotmail.com Sat May 24 14:21:22 2003 From: dufferjames@hotmail.com (James Duffer) Date: Sat, 24 May 2003 08:21:22 -0500 Subject: [Antennas] Re: Painting Antennas and Fiberglass Spreaders for Quads Message-ID: I too thought that Barry's post was very interesting and very suitable for this thread. I think that he emphasize the practical characteristics needed for paint used in painting a radome. I hope this does not discourage Barry from making excellent responses as he has in the past. There is no need to "dumb down" his replies. Some have said that the qualifications for amateur radio has been "dumbd down" by relaxing certain requirements in the amateur radio examinations for various classes orf license. This attitude is certainly not needed for the replies to questions and information sought on this reflector, or for other reflectors for that matter. I was particularily interested in his answer as I have while with the FAA, worked with Essco a leading radome manufacturer install 57 ft and 60 ft radomes on FAA en-route radars. These radomes usually required painting after several years of use, and there were many issues that were of concern regarding the coating, durability being one of many. While some may become "bored" with a detailed and informative reply they simply can delete it, but, others may enjoy reading and learning. So Barry don't cut us short or think that we won't benefit from your answers. 73, Jim, wd4air >From: Bill Aycock >To: "W1GOR" , >Subject: Re: [Antennas] Re: Painting Antennas and Fiberglass Spreaders for >Quads >Date: Sat, 24 May 2003 06:46:58 -0500 > >Larry >Your attack (yes) was not very productive. I have seen so MUCH crap on this >subject that it was good to see someone with real knowledge expound. It WAS >needed, to clear up the rumor and folklore that had been spouted.. >BTW you need a lesson in netiquette- there was no need to keep ALL of his >post as an enclosure to your diatribe. It just adds to the traffic load >with no benefit. >Bill > >At 07:18 AM 5/24/2003 -0400, you wrote: > >>Barry, >> >>Your response, albeit interesting, reminds me of a fellow whom I knew many >>years ago... He was the type who, when asked, "what time is it..?", would >>respond with a lengthy lesson on quantum physics and celestial >>mechanics..., >>when all I wanted was the correct time...! > >Bill Aycock - W4BSG >Woodville, Alabama > _________________________________________________________________ Tired of spam? Get advanced junk mail protection with MSN 8. http://join.msn.com/?page=features/junkmail From k6mhe@mendolink.com Sat May 24 14:27:53 2003 From: k6mhe@mendolink.com (Dan Richardson) Date: Sat, 24 May 2003 06:27:53 -0700 Subject: [Antennas] Re: Painting Antennas and Fiberglass Spreaders for Quads In-Reply-To: <001601c321e6$3fa0bfc0$8bd7c618@maine.rr.com> References: <20030523080147.9BA5F328ACD@mailman.qth.net> <007e01c321b7$ccf13f00$a74562d8@ntelos.net> Message-ID: <5.1.0.14.2.20030524062202.00b44bc8@mail.mendolink.com> Larry, I disagree with you entirely. I found the response very enlightening. Not only was the answer provided, but the reasoning behind it. Obviously, it took considerable time and effort to compose and I, for one, very much appreciate it. Danny, K6MHE At 07:18 AM 5/24/2003 -0400, you wrote: >Barry, > >Your response, albeit interesting, reminds me of a fellow whom I knew many >years ago... He was the type who, when asked, "what time is it..?", would >respond with a lengthy lesson on quantum physics and celestial mechanics..., >when all I wanted was the correct time...! > >BTW, the manufacturers of these vertical antennas DO refer to the housings >as RADOMES, so that's why the article also used the term RADOME. While your >frequent responses are interesting, they tend toward being pedantic and >extreme... It would be in the interest of all readers for you to submit >simplified responses, and stick to the issue at hand, rather than submitting >a professional resume along with your comments... Since my professional >credentials are similar to yours, I find that the best response is one that >addresses the majority of readers. Also, I'm not into pissing matches, >because they bore the hell out of me... besides, I refuse to have a >'battle-of-wits' with unarmed men..! > >I heard a short story about a little boy who asked his Mom and Dad, "Where >did I come from?"... Mom and Dad became flustered, and tried with much >stumbling, to explain the 'birds-and-the-bees' to their son... When they >were finished with their somewhat embarrassing answer, the little boy said, >"Heck, I knew all of that from my sex education class..., but what I want to >know is WHERE I came from... Billy is from Philadelphia, John is from >Houston and I just want to know WHERE I came from.." > >and so it goes... > >73, Larry - W1GOR From elemmon@impulse.net Sat May 24 15:25:37 2003 From: elemmon@impulse.net (Eric Lemmon) Date: Sat, 24 May 2003 07:25:37 -0700 Subject: [Antennas] Painting of Antenna Radomes References: <20030523080147.9BA5F328ACD@mailman.qth.net> <007e01c321b7$ccf13f00$a74562d8@ntelos.net> Message-ID: <3ECF80E1.E32E2C83@impulse.net> Most manufacturers of commercial-grade antennas have researched this topic to a far greater depth than anyone else, so I recommend going to them for advice on painting of radomes. One source of information is Decibel Products' Technical Library application note at: www.decibelproducts.com/dbtech_2.html 73, Eric Lemmon WB6FLY From W9IXX@arrl.net Sat May 24 15:48:12 2003 From: W9IXX@arrl.net (Phil Florig) Date: Sat, 24 May 2003 10:48:12 -0400 Subject: Fwd: Re: [TowerTalk] [Antennas] Painting Fiberglass Antenna Radomes Message-ID: <5.2.0.9.2.20030524104506.0492bec0@mail.alltel.net> Hi, Had no problems with PDF file here. Have no blockers or firewall. Used Acrobat 5. and loaded fine. Saved as file and reads fine. 73 Phil W9IXX >Hmmm .. gonna have to try it again .. perhaps my main brain is "cooked" --- >or, you don't have any popup blocker, etc. there Jim! It is just VERY >possible I have some "saviour" program, that is causing this prob .. SILLY >ME! As to ACROBAT . I HAVE THE ENTIRE program, latest-greatest, ADOBE >ACROBAT 5.XX --- cost a bunch .. ahh,,,,,,, whatta hey .. BTW -- FYI, all. >the term .. PDF = "Portable Document File" --- >----- Original Message ----- >From: "Jim W7RY" >To: "AA6DX" >Sent: Friday, May 23, 2003 3:48 PM >Subject: Re: [TowerTalk] [Antennas] Painting Fiberglass Antenna Radomes > > > > Its a PDF file... > > No popups seen here! > > > > 73 > > Jim W7RY Philip Florig e-mail:pflorig@ieee.org 115 Horne Rd. (or):W9IXX@arrl.net Columbus, NC. 28722 amateur radio:W9IXX USA also:J3X-T30,31,32,33P team member:AH1A-J3A ----------------------------------------------- IPR Systems, Inc. tel: 1-708-385-7500 11651 Mayfield Ave. fax: 1-708-385-7515 Alsip, IL. 60803 email:info@iprsys.com USA INDUSTRIAL POWER SUPPLIES & RECTIFIERS ----------------------------------------------- From w4tg@bellsouth.net Sat May 24 19:50:56 2003 From: w4tg@bellsouth.net (Harvey&Bessie) Date: Sat, 24 May 2003 14:50:56 -0400 Subject: [Antennas] Re: Painting Antennas and Fiberglass Spreadersfor Quads References: <20030523080147.9BA5F328ACD@mailman.qth.net> <007e01c321b7$ccf13f00$a74562d8@ntelos.net> <5.1.0.14.2.20030524062202.00b44bc8@mail.mendolink.com> Message-ID: <3ECFBF10.9C6C90A@bellsouth.net> Yes! shame on you larry! Barry's response was very informative, the kind of information that makes this "newsgroups" worth while. W4tg/Harvey From ornitz@tricon.net Sat May 24 23:49:54 2003 From: ornitz@tricon.net (Barry L. Ornitz) Date: Sat, 24 May 2003 18:49:54 -0400 Subject: [Antennas] Re: Painting Antennas and Fiberglass Spreaders for Quads References: <20030523080147.9BA5F328ACD@mailman.qth.net> <007e01c321b7$ccf13f00$a74562d8@ntelos.net> <001601c321e6$3fa0bfc0$8bd7c618@maine.rr.com> Message-ID: <003501c32246$cbd9a780$d35f62d8@ntelos.net> Unable to argue on the technical merits, Steve, W1GOR, ranted the following: > Your response, albeit interesting, reminds me of a fellow > whom I knew many years ago... He was the type who, when > asked, "what time is it..?", would respond with a lengthy > lesson on quantum physics and celestial mechanics..., > when all I wanted was the correct time...! I have found most readers here actually wish to learn some science behind their hobby. If you do not, that is certainly your right. There was nothing wrong with the website you suggested except that it made it sound like there was only one exact type of paint that could be used which is certainly not the case. > BTW, the manufacturers of these vertical antennas DO refer > to the housings as RADOMES, so that's why the article also > used the term RADOME. That does not make them right. :-) The definition I used is basically that given in Chapter 44, Radomes, in Johnson and Jasik's "Antenna Engineering Handbook, 2ed." The distinction is important in this discussion for the reasons I listed. Quoting from the book, "Radome effects can be qualitatively explained and understood in terms of TEM (plane) wave propagation through and reflection from planar dielectric panels. The curved radome wall is considered to be locally plane at each point. Waves emanating from the enclosed transmitting antenna are also considered to be locally plane at each point of incidence on the radome wall. The reflected and transmitted waves can then be approximated from plane-sheet theory, and the resultant effects on overall antenna performance can be calculated." This is quite different than the situation where the insulator is located in the near-field (reactive field) of the antenna where the dielectric properties of the insulator affect the resonance and efficiency of the antenna itself. >While your frequent responses are interesting, they tend >toward being pedantic and extreme... It would be in the >interest of all readers for you to submit simplified >responses, and stick to the issue at hand, rather than >submitting a professional resume along with your comments... No, just SOME readers. These are the people who ask "is a vertical better than a long wire" without ever understanding why the answer depends on a myriad of conditions. >Since my professional credentials are similar to yours, I >find that the best response is one that addresses the >majority of readers. I seriously doubt the first statement. While my Ph.D. is in chemical engineering, I have taken graduate courses in antennas and transmission lines, integrated circuit manufacturing and basic semiconductors. My industrial work was primarily in online instrumentation, but I was the Eastman expert in the electrical properties of plastics and polymers. While I was located in the Research Laboratories, I spent considerable time assisting their Technical Service department in areas such as dielectric heating and sealing, and in electrical property measurements such as surface and bulk resistivity, insulation resistance, surface arc tracking, electrostatic spraying, and static electricity abatement. Much of Eastman's business is in providing materials to the paint industry, so it is natural to have to be familiar with paint technology. >Also, I'm not into pissing matches, because they bore the >hell out of me... besides, I refuse to have a 'battle-of- >wits' with unarmed men..! It surely sounds like you are. Yet you have not provided any technical or scientific point to argue on. Instead, you claim my answers are too technical and boring. Perhaps they are for some readers, but then again, this is a technical hobby and I hope the readership will learn something of science and not go to the lowest common denominator of appliance operators so prevalent these days. I received several encouraging notes from other readers about this same article on paints with yours being the only negative one. Besides, this response contradicts two personal notes you sent me earlier this year. In one, you noted my article was "interesting and informative" and then asked for a copy of my table of galvanic series of metals. In the second, you thanked me for my explanation of the characteristic impedance of cables noting it was clearer than the one your professors taught years ago. If you wish to debate technical points in my articles, please bring them up. If you do not understand some of my points, ask me to explain further. But don't expect me to answer questions like the "vertical versus long wire" with a one word answer. 73, Barry L. Ornitz WA4VZQ ornitz@tricon.net As to misspelling you call, I apologize. As my peripheral neuropathy progresses, I find touch typing to be more difficult. I try to proofread everything, but I did not catch this error. From w4tg@bellsouth.net Sun May 25 01:08:34 2003 From: w4tg@bellsouth.net (Harvey&Bessie) Date: Sat, 24 May 2003 20:08:34 -0400 Subject: [Antennas] Re: Painting Antennas and Fiberglass Spreaders for Quads References: <20030523080147.9BA5F328ACD@mailman.qth.net> <007e01c321b7$ccf13f00$a74562d8@ntelos.net> <001601c321e6$3fa0bfc0$8bd7c618@maine.rr.com> <003501c32246$cbd9a780$d35f62d8@ntelos.net> Message-ID: <3ED00982.AC581681@bellsouth.net> Amen! Brother Barry! Harvey/W4TG From hankarn@pacbell.net Sun May 25 02:15:43 2003 From: hankarn@pacbell.net (hankarn) Date: Sat, 24 May 2003 18:15:43 -0700 Subject: [Antennas] Re: Painting Antennas and Fiberglass Spreaders for Quads References: <20030523080147.9BA5F328ACD@mailman.qth.net> <007e01c321b7$ccf13f00$a74562d8@ntelos.net> <001601c321e6$3fa0bfc0$8bd7c618@maine.rr.com> <003501c32246$cbd9a780$d35f62d8@ntelos.net> Message-ID: <011501c3225b$2a3301a0$15acc53f@danhome> Barry, BRAVO. Just keep the info coming anytime you see fit. 73 Hank KN6DI From W9IXX@arrl.net Sun May 25 19:18:42 2003 From: W9IXX@arrl.net (Phil Florig) Date: Sun, 25 May 2003 14:18:42 -0400 Subject: [Antennas] Recent article in EDN "Tab antenna" Message-ID: <5.2.0.9.2.20030525135419.00a46ce0@pop.mindspring.com> Hi all, Thought this may be of interest to some. Article in EDN magazine on a 915MHZ ant better than the 1/4wave monopole from a space standpoint. This was done on pc board but assume (never do) can be free space with proper modelling. The link is as follows: http://www.e-insite.net/ednmag/index.asp?layout=articlePrint&articleID=CA296495 Thought maybe some of the experts could look at and see if can be used on the lower bands. I am just starting to look at modelling and this looks too complicated for a beginner. Maybe a great test for the more advanced. HI.... 73 Phil W9IXX ----------------------------------------------- Philip Florig e-mail:pflorig@ieee.org 115 Horne Rd. (or):W9IXX@arrl.net Columbus, NC. 28722 amateur radio:W9IXX USA also:J3X-T30,31,32,33P team member:AH1A-J3A ----------------------------------------------- IPR Systems, Inc. tel: 1-708-385-7500 11651 Mayfield Ave. fax: 1-708-385-7515 Alsip, IL. 60803 email:info@iprsys.com USA INDUSTRIAL POWER SUPPLIES & RECTIFIERS ----------------------------------------------- From jimsim@adelphia.net Sun May 25 19:54:23 2003 From: jimsim@adelphia.net (Jim Simmons) Date: Sun, 25 May 2003 14:54:23 -0400 Subject: [Antennas] Painting of Antenna Radomes References: <20030523080147.9BA5F328ACD@mailman.qth.net> <007e01c321b7$ccf13f00$a74562d8@ntelos.net> <3ECF80E1.E32E2C83@impulse.net> Message-ID: <006c01c322ef$0ec49c00$4bb93418@rhmdky.adelphia.net> Why not just using latex boat paint? The kind the use on sailboats. They stand up under horrible conditions. Just a thought! Jim, KF4TUN ----- Original Message ----- From: "Eric Lemmon" To: "Barry L. Ornitz" Cc: Sent: Saturday, May 24, 2003 10:25 AM Subject: [Antennas] Painting of Antenna Radomes > Most manufacturers of commercial-grade antennas have researched this > topic to a far greater depth than anyone else, so I recommend going to > them for advice on painting of radomes. One source of information is > Decibel Products' Technical Library application note at: > > www.decibelproducts.com/dbtech_2.html > > 73, Eric Lemmon WB6FLY > > - - - > > Your moderator for this list is: > Larry Wilson KE1HZ antennas-owner@mailman.qth.net > _______________________________________________ > Antennas mailing list > Antennas@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/antennas From elemmon@impulse.net Sun May 25 21:29:17 2003 From: elemmon@impulse.net (Eric Lemmon) Date: Sun, 25 May 2003 13:29:17 -0700 Subject: [Antennas] Painting of Antenna Radomes References: <20030523080147.9BA5F328ACD@mailman.qth.net> <007e01c321b7$ccf13f00$a74562d8@ntelos.net> <3ECF80E1.E32E2C83@impulse.net> <006c01c322ef$0ec49c00$4bb93418@rhmdky.adelphia.net> Message-ID: <3ED1279D.BCF0BADD@impulse.net> Jim, I think it's significant that none of the commercial antenna manufacturers suggest using latex boat paint for painting their antennas or radomes. With all due respect to the salt-water exposure that sailboats may endure, the abuse that a hilltop antenna gets is- in my opinion- far more severe than any sailboat will experience. When you want to protect a very expensive antenna, is it a good idea to scrimp on the quality of paint? Moreover, the attributes of a good marine paint do not necessarily equate to the attributes of a goood radome paint. 73, Eric Lemmon WB6FLY Jim Simmons wrote: > > Why not just using latex boat paint? The kind the use on sailboats. They stand up under horrible conditions. Just a thought! From ornitz@tricon.net Mon May 26 00:32:33 2003 From: ornitz@tricon.net (Barry L. Ornitz) Date: Sun, 25 May 2003 19:32:33 -0400 Subject: [Antennas] Painting of Antenna Radomes References: <20030523080147.9BA5F328ACD@mailman.qth.net> <007e01c321b7$ccf13f00$a74562d8@ntelos.net> <3ECF80E1.E32E2C83@impulse.net> <006c01c322ef$0ec49c00$4bb93418@rhmdky.adelphia.net> Message-ID: <004601c32315$ebaa5580$605b62d8@ntelos.net> Jim Simmons, KF4TUN, asked: > Why not just using latex boat paint? The kind the use on > sailboats. They stand up under horrible conditions. This is a good question. The new high-gloss latex enamels are actually quite different from the latex paints of years ago. They use an acrylic chemistry that produces a far more durable paint, yet can still be applied as a water-based emulsion. They do hold up well, and most of the adhesion problems have been solved. However, these paints are still a little porous letting some moisture through. On old, weathered fiberglass, I think I would still use an epoxy or urethane paint to keep the moisture out. But if you wish to paint a metal antenna to hide it, or protect it from a nasty environment (like salt spray near the ocean, or acid rain, etc.) the new acrylic latex paints should work fine. Watch out about paints sold by boating dealers. The paint is often no different from quality paint sold for homes, but because of the "boat" in the name you usually pay more. [Private airplane owners are probably more familiar with this issue. An ordinary oil filter that you buy for a few bucks at the local auto parts store suddenly costs 10X as much as soon as an FAA number is applied and sold in an aviation parts place!] 73, Barry WA4VZQ ornitz@tricon.net From ve7hcb@rac.ca Mon May 26 00:23:40 2003 From: ve7hcb@rac.ca (Chris BONDE) Date: Sun, 25 May 2003 16:23:40 -0700 Subject: [Antennas] Re: Painting Antennas and Fiberglass Spreaders for Quads In-Reply-To: <011501c3225b$2a3301a0$15acc53f@danhome> References: <20030523080147.9BA5F328ACD@mailman.qth.net> <007e01c321b7$ccf13f00$a74562d8@ntelos.net> <001601c321e6$3fa0bfc0$8bd7c618@maine.rr.com> <003501c32246$cbd9a780$d35f62d8@ntelos.net> Message-ID: <4.3.1.1.20030525162107.00ad9bf0@mail.netidea.com> At 06:15 PM 2003-05-24 -0700, you wrote: >Barry, BRAVO. Just keep the info coming anytime you see fit. >73 >Hank >KN6DI I concure!! I have set up a special file to copy all of Barry's comments. I might not need them now but may in the future. BUT the reading and the attempt to fully understand them has helped me very much. Thank you Barry. Yes, keep the info coming. Chris opr VE7HCB From w4tg@bellsouth.net Mon May 26 01:11:51 2003 From: w4tg@bellsouth.net (Harvey&Bessie) Date: Sun, 25 May 2003 20:11:51 -0400 Subject: [Antennas] Re: Painting Antennas and Fiberglass Spreadersfor Quads References: <20030523080147.9BA5F328ACD@mailman.qth.net> <007e01c321b7$ccf13f00$a74562d8@ntelos.net> <001601c321e6$3fa0bfc0$8bd7c618@maine.rr.com> <003501c32246$cbd9a780$d35f62d8@ntelos.net> <4.3.1.1.20030525162107.00ad9bf0@mail.netidea.com> Message-ID: <3ED15BC7.450D392C@bellsouth.net> It is important to note what he has to say in the 4th paragraph of his posting, where it begins: "To begin, a radome is more properly..." The effect of such a dome covering over an antenna is quite different at VHF and UHF (where the dome material is in the near field) than it is at microwave frequencies, where it is in the far field. Harvey/W4TG From zl3nz@xtra.co.nz Mon May 26 02:28:38 2003 From: zl3nz@xtra.co.nz (Graham Dacombe) Date: Mon, 26 May 2003 13:28:38 +1200 Subject: [Antennas] High Sierra or Tarheel Message-ID: <5.2.0.9.2.20030526132607.009f05d0@pop3.xtra.co.nz> Greetings from Emmanuel House, I wish to purchase a mobile Antenna and would like to know the Pro's and Con's as to which of these brands to purchase. Regards, Graham ZL3NZ. Graham & Mary Dacombe Emmanuel House 20 Allin Drive, Waikuku Beach, North Canterbury 8254, New Zealand. Phone: +64-3-312 7782 Fax: +64-3-312 7783 Website: http://www.nzhomestay.co.nz/emmanuelhouse.html http://www.travelwise.co.nz/listings/Emmanuel_House.html --- StripMime Report -- processed MIME parts --- multipart/alternative text/plain (text body -- kept) text/html The reason this message is shown is because the post was in HTML or had an attachment. Attachments are not allowed. To learn how to post in Plain-Text go to: http://www.expita.com/nomime.html --- From zl3nz@xtra.co.nz Mon May 26 04:24:31 2003 From: zl3nz@xtra.co.nz (Graham Dacombe) Date: Mon, 26 May 2003 15:24:31 +1200 Subject: [Antennas] High Sierra or Tarheel Message-ID: <5.2.0.9.2.20030526151805.009f4250@pop3.xtra.co.nz> Greetings from Emmanuel House, I wish to purchase a mobile Antenna and would like to know the Pro's and Con's as to which of these brands to purchase. Regards, Graham ZL3NZ. Graham & Mary Dacombe Emmanuel House 20 Allin Drive, Waikuku Beach, North Canterbury 8254, New Zealand. Phone: +64-3-312 7782 Fax: +64-3-312 7783 Website: http://www.nzhomestay.co.nz/emmanuelhouse.html http://www.travelwise.co.nz/listings/Emmanuel_House.html From wa2bpe@infoblvd.net Mon May 26 19:02:14 2003 From: wa2bpe@infoblvd.net (WA2BPE) Date: Mon, 26 May 2003 14:02:14 -0400 Subject: [Antennas] Painting of Antenna Radomes References: <20030523080147.9BA5F328ACD@mailman.qth.net> <007e01c321b7$ccf13f00$a74562d8@ntelos.net> <3ECF80E1.E32E2C83@impulse.net> <006c01c322ef$0ec49c00$4bb93418@rhmdky.adelphia.net> <004601c32315$ebaa5580$605b62d8@ntelos.net> Message-ID: <3ED256A5.CC9A96E4@infoblvd.net> I would be careful of what paint is used as some may be good absorbers at microwaves - you may wind up with something waterproof - and no signal! No, I have no data to back up what will/won't work. Also, I am not sure, but this may hv been discussed some time back; perhaps an archive search is in order. Perhaps check the microwave archives too. 73, Tom - WA2BPE "Barry L. Ornitz" wrote: > Jim Simmons, KF4TUN, asked: > > > Why not just using latex boat paint? The kind the use on > > sailboats. They stand up under horrible conditions. > > This is a good question. The new high-gloss latex enamels are > actually quite different from the latex paints of years ago. > They use an acrylic chemistry that produces a far more durable > paint, yet can still be applied as a water-based emulsion. > > They do hold up well, and most of the adhesion problems have > been solved. However, these paints are still a little porous > letting some moisture through. On old, weathered fiberglass, > I think I would still use an epoxy or urethane paint to keep > the moisture out. But if you wish to paint a metal antenna to > hide it, or protect it from a nasty environment (like salt > spray near the ocean, or acid rain, etc.) the new acrylic > latex paints should work fine. > > Watch out about paints sold by boating dealers. The paint is > often no different from quality paint sold for homes, but > because of the "boat" in the name you usually pay more. > > [Private airplane owners are probably more familiar with this > issue. An ordinary oil filter that you buy for a few bucks at > the local auto parts store suddenly costs 10X as much as soon > as an FAA number is applied and sold in an aviation parts > place!] > > 73, Barry WA4VZQ ornitz@tricon.net > > - - - > > Your moderator for this list is: > Larry Wilson KE1HZ antennas-owner@mailman.qth.net > _______________________________________________ > Antennas mailing list > Antennas@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/antennas From ornitz@tricon.net Tue May 27 00:51:16 2003 From: ornitz@tricon.net (Barry L. Ornitz) Date: Mon, 26 May 2003 19:51:16 -0400 Subject: [Antennas] Re: Antennas digest, Vol 4 #137 - 9 msgs References: <20030526080141.5831B328A5D@mailman.qth.net> Message-ID: <001901c323e1$b47535e0$965b62d8@ntelos.net> Phil Florig, W9IXX, asked about a "tab antenna" described in Electronic Desigh News magazine for the 915 MHz band. > http://www.e-insite.net/ednmag/index.asp?layout=articlePrint&articleID =CA296495 > > Thought maybe some of the experts could look at and see if > can be used on the lower bands. I am just starting to look > at modelling and this looks too complicated for a beginner. > Maybe a great test for the more advanced. HI.... Different from the traditional microstrip patch antenna designs often used at microwave frequencies (which are also small), this antenna still uses dielectric loading (via the printed circuit laminate) to shorten its physical length. Building such an antenna is pretty trivial, but the modeling is certainly not. The author of the article discusses how he simulated the distributed capacitance and losses of the laminate by using a number of discrete loads. This sort of modeling is generally NOT for the beginner. The antenna can be scaled for lower frequencies, but you will run into difficulties with size and thickness if you try to use this antenna design below the 440 MHz band. You will also run into difficulties using more than a dozen watts or so of power as the board traces are small and dielectric heating of the laminate will become a problem. This antenna, as the author noted, does have reduced efficiency. Its only real advantage is a reduction in size over a conventional antenna, and even here the reduction is not that much. I suspect the author designed this antenna for use with low-power wireless devices where size was more important than efficiency. If you are looking at reduced-size high frequency antennas that still have reasonable efficiencies, I suggest you dig up the articles published by Jerry Sevick, W2FMI, in QST a few years ago. Properly done, a reduced-size antenna can be quite efficient - BUT at the expense of bandwidth. For example, I built a three foot long CB antenna for a friend back in the early 1970's. It far out-performed any shortened commercial CB antenna on the market, and almost duplicated the performance of a full-size whip. But it was rather narrow- banded! It had a 1:1 VSWR on Channel 19, a 2:1 VSWR on either channel immediately above or below, and was totally useless on other channels. Being passed by another car slightly detuned the antenna, and a big truck nearby could change the resonance by at least 10 kHz. If this antenna were mande of lossier materials, its bandwidth could have been much better. But the perfomance would have suffered greatly. 73, Dr. Barry L. Ornitz WA4VZQ ornitz@tricon.net From ornitz@tricon.net Tue May 27 01:13:13 2003 From: ornitz@tricon.net (Barry L. Ornitz) Date: Mon, 26 May 2003 20:13:13 -0400 Subject: [Antennas] Painting of Antenna Radomes References: <20030523080147.9BA5F328ACD@mailman.qth.net> <007e01c321b7$ccf13f00$a74562d8@ntelos.net> <3ECF80E1.E32E2C83@impulse.net> <006c01c322ef$0ec49c00$4bb93418@rhmdky.adelphia.net> <004601c32315$ebaa5580$605b62d8@ntelos.net> <3ED256A5.CC9A96E4@infoblvd.net> Message-ID: <002d01c323e4$c71eb560$965b62d8@ntelos.net> Tom, WA2BPE, wrote: > I would be careful of what paint is used as some may be good absorbers > at microwaves - you may wind up with something waterproof - and no > signal! No, I have no data to back up what will/won't work. Also, I am > not sure, but this may hv been discussed some time back; perhaps an > archive search is in order. Perhaps check the microwave archives too. There are some very different considerations when painting microwave antennas as I clearly stated earlier. For painting a radome, where the signal must pass through the coating, you need not only low loss, but a dielectric constant similar to the existing radome material. Since many radomes are made of acrylic plastics for low losses, you also need to make sure the paint is compatible here. Many solvents will either soften or dissolve these plastics, and while other solvents may not, they can still cause stress corrosion cracking of these plastics resulting in an extreme loss of strength. Painting a microwave reflector is an entirely different issue. High dielectric constant is of benefit here. Titanium dioxide, the preferred white pigment of most paints these days, has an exceptionally high dielectric constant. In fact, this material is commonly used in the ceramics of high-K ceramic capacitors. It works great in paint used on reflectors like a parabolic dish. But it is not suitable for use in radome paints. Lead oxide might be more suitable from an electrical standpoint, but its toxicity keeps it from being used in modern paints. The painting of microwave antennas is a complex subject with lots of trade-offs. To read more about the materials, consult the reference to Jasik and Johnson I gave earlier. 73, Barry WA4VZQ ornitz@tricon.net From Punkymcd@pacbell.net Tue May 27 20:33:45 2003 From: Punkymcd@pacbell.net (Punkymcd@pacbell.net) Date: Tue, 27 May 2003 12:33:45 -0700 Subject: [Antennas] Auto antenna tuner wanted Message-ID: <3ED3BD99.1080003@pacbell.net> Anyone out there have an auto atenna tuner LDG AT-11 or Z-11 kit or wired they'd like to sell? De Don, W6OA From k6mhe@mendolink.com Thu May 29 02:48:47 2003 From: k6mhe@mendolink.com (Dan Richardson) Date: Wed, 28 May 2003 18:48:47 -0700 Subject: [Antennas] Trap Question Message-ID: <5.1.0.14.2.20030528184347.00b974f0@mail.mendolink.com> I have read from several sources that if one is to design a trap (such as used in multi-band trap dipoles) its resonate frequency should be lower than the desired operating frequency. However, I have never seen nor heard of the reasoning behind that statement. Does anyone know the rational for that? Please, I'm not interested in the pros and cons of trap antennas. I am well aware of those. I just want to know why the lower frequency is recommended. 73 Danny, K6MHE From ernie@netvision.net.il Thu May 29 05:29:10 2003 From: ernie@netvision.net.il (Tsachy L) Date: Thu, 29 May 2003 07:29:10 +0300 Subject: [Antennas] Cushcraft R4 info Message-ID: <046e01c3259a$da144a60$425bebd4@ernie> Hello group I'm looking for schema \ details of the R4's matching unit ("black-box"), and the user manual. Can anyone point me to a link? Thanks in advance, Isaac, 4Z4TL http://www.iarc.org/~4z4tl/ ernie@netvision.net.il 4z4tl@iarc.org From Punkymcd@pacbell.net Thu May 29 07:04:14 2003 From: Punkymcd@pacbell.net (Punkymcd@pacbell.net) Date: Wed, 28 May 2003 23:04:14 -0700 Subject: [Antennas] Trade laptop for AT-11 or Z-11 auto antenna tuner References: <20030528080122.DA210328A56@mailman.qth.net> Message-ID: <3ED5A2DE.7010501@pacbell.net> Trade: AMD-K6 processor 266mHz Pentium Compaq Presario 1235 laptop with Win 98, Users Guide, 100mb external zip drive. Laptop has a CD Rom, 4 gig hard drive, 56k modem, MS Office 2000, Original Compaq software, carrying case, power supply, 32meg ram, 3.5" floppy drive. Trade for an AT-11 or preassembled Z-11 auto antenna tuner. Thanks. De Don, W6OA (925)443-1769 Livermore, Ca. From demetre@fastmail.ca Thu May 29 08:58:19 2003 From: demetre@fastmail.ca (Demetre Koumanakos) Date: Thu, 29 May 2003 03:58:19 -0400 (EDT) Subject: [Antennas] Vertical Loop questions Message-ID: <3ED5BD9B.0000B7.45288@ns.interchange.ca> Hi All, I'm about to install a vertical copper wire loop for 20 meters on my roof to replace a self supporting (single center support with arms extending from the center) vertical loop that broke this past winter. this time I'll be using a support on each side (10 meter long fiberglass fishing rods) which will give me a square (instead of the old diamond) shape loop. Question1: The diamond shape loop fed at the bottom performed very well, will the square shape bottom fed have a similar performance ?? Question2: Because of the support orientation the lower side of the antenna wire will be passing near an existing short antenna, will this affect the performance of the loop ?? PSE reply direct also sv1ens@arrl.net , e-mail from the reflector gets lost in cyberspace at times... 73 Demetre - SV1ENS _________________________________________________________________ http://fastmail.ca/ - Fast Secure Web Email for Canadians --- StripMime Report -- processed MIME parts --- multipart/mixed text/plain (text body -- kept) The reason this message is shown is because the post was in HTML or had an attachment. Attachments are not allowed. To learn how to post in Plain-Text go to: http://www.expita.com/nomime.html --- From k4sqr@juno.com Thu May 29 10:46:11 2003 From: k4sqr@juno.com (Jim Miller) Date: Thu, 29 May 2003 05:46:11 -0400 Subject: [Antennas] Cushcraft R4 info Message-ID: <20030529.054612.1064.1.K4SQR@juno.com> See www.iol.ie/~bravo/r7_vertical.htm if link fails, do search for EI7BA. This site has R5 & R7 schematics. That will be close for your R4. Good luck, Jim Miller, K4SQR http://www.comteksystems.com 4-Square Experts, Stack Yagi & Remote Antenna Switching Systems On Thu, 29 May 2003 07:29:10 +0300 Tsachy L writes: > Hello group > I'm looking for schema \ details of the R4's matching unit > ("black-box"), > and the user manual. > Can anyone point me to a link? > Thanks in advance, Isaac, 4Z4TL > http://www.iarc.org/~4z4tl/ > ernie@netvision.net.il 4z4tl@iarc.org > > > - - - > > Your moderator for this list is: > Larry Wilson KE1HZ antennas-owner@mailman.qth.net > _______________________________________________ > Antennas mailing list > Antennas@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/antennas > > From KG4FET@aol.com Thu May 29 12:48:58 2003 From: KG4FET@aol.com (KG4FET@aol.com) Date: Thu, 29 May 2003 07:48:58 EDT Subject: [Antennas] Butternut HF6V 15 mtr Wire Message-ID: <1e9.9ba2b50.2c074daa@aol.com> Good Day to all, I am looking for some info on just the wire portion of the Butternut HF6V. I was given one, but it does not have the 15 mtr portion on it. What I was wondering is there anything special on the 15 mtr wire making it hard to duplicate myself. Basically what I need to know is the bottom of the wire is "loaded," or needs anything special besides the bracket, and is the wire insulated from the bracket and wire loaded by capacitance, or is it hot? I hope I have made some sense here and any help would be appreciated. Take Care, God Bless and 73 DE KG4FET Sandor BTW Antenna resonate on all bands but 15 with no grounds attached at this point. --- StripMime Report -- processed MIME parts --- multipart/alternative text/plain (text body -- kept) text/html The reason this message is shown is because the post was in HTML or had an attachment. Attachments are not allowed. To learn how to post in Plain-Text go to: http://www.expita.com/nomime.html --- From kukl@cybrquest.com Thu May 29 14:01:42 2003 From: kukl@cybrquest.com (John Kuklewicz N7ZN) Date: Thu, 29 May 2003 06:01:42 -0700 Subject: [Antennas] Butternut HF6V 15 mtr Wire References: <1e9.9ba2b50.2c074daa@aol.com> Message-ID: <3ED604B6.4060207@cybrquest.com> Sandor, I have a Butternut HF6V. Without going out and taking the thing down, I can make the following observations to answer your questions. Bencher's Website page about he HF6V: http://www.bencher.com/hf6vx.html KG4FET@aol.com wrote: > Good Day to all, > I am looking for some info on just the wire portion of the Butternut HF6V. I > was given one, but it does not have the 15 mtr portion on it. What I was > wondering is there anything special on the 15 mtr wire making it hard to > duplicate myself. No, it is just an insulated wire. The top-most bracket supports the wire at the proper distance from the antenna and also shorts the wire to the tubing at that point. This wire is simply a 1/4 wave decoupling stub to force only the lower 1/4 wave of the antenna to radiate on 15 meters. The brackets lower on the mast merely serve to keep the wire properly spaced from the antenna. You can download a manual pdf at: http://www.bencher.com/pdf_download.html#vert_ant Also on that page is a parts list for the antenna. > Basically what I need to know is the bottom of the wire is > "loaded," or needs anything special besides the bracket, and is the wire insulated > from the bracket and wire loaded by capacitance, or is it hot? There is no loading at the bottom of the wire. Butternut recommends that any excess wire be wrapped back onto itself for tuning purposes. Be aware that when/if you improve your radial field, the tuning will change. I have found that the 30m and 20m tuning adjustments do interact. Also some slight interaction with the 40m tuning. I strongly suggest you use an antenna analyzer to tune this thing - Following the manual procedure with the analyzer is pretty straight forward. Remember to tune for RESONANCE, not necessarily minimum SWR.(i.e. X-0) With a good radial field the impedance at resonance will not be 50 ohms. > I hope I have > made some sense here and any help would be appreciated. > Take Care, God Bless and 73 > DE KG4FET Sandor > BTW Antenna resonate on all bands but 15 with no grounds attached at this > point. > Again, be aware that when/if you improve the radial field, the tuning will change. ANd, the antenna will not play very well unless you are able to get a good near-field radial screen set up. The Bencher web site has some very good technical articles about the care and feeding of this sort of antenna. url: http://www.bencher.com/pdf_download.html#tech_notes One downside of a good radial field, is that on the lower bands - especially 80 meters- the tuning becomes very sharp. My setup uses 63 radials, each 52 feet long laid on tip of the sod and tied to a perimeter wire. On 80 meters my 2:1 SWR range is about 15kHz and about 150kHz on 40 meters. This is measured at the end of the antenna's 20 meter matching section. Back at my shack, the tuning ranges appear broader because of attenuation in my rather long feedline (about 250 ft of RG-213). I hope this helps. vy 73; John N7ZN > .... From va3pl@cuic.ca Thu May 29 20:23:05 2003 From: va3pl@cuic.ca (VeeAthreePL) Date: Thu, 29 May 2003 15:23:05 -0400 Subject: [Antennas] Refurbishing old TH6DXX In-Reply-To: <3ED5BD9B.0000B7.45288@ns.interchange.ca> References: <3ED5BD9B.0000B7.45288@ns.interchange.ca> Message-ID: Has any one complete listing of bolts and nuts for TH6DXX? Are those "stainless steel" bolts and nuts from Home Depot are really stainless steel? Suggestions? Andy VA3PL From w5mc@austin.rr.com Fri May 30 04:38:33 2003 From: w5mc@austin.rr.com (Herschel McCullough) Date: Thu, 29 May 2003 22:38:33 -0500 Subject: [Antennas] Refurbishing old TH6DXX References: <3ED5BD9B.0000B7.45288@ns.interchange.ca> Message-ID: <01da01c3265c$f4001a40$6400a8c0@radioshack> MFJ HyGain will gladly furnish you a complete TH-6 manual with a BOM bill of materials.. they will do this for FREE mac/mc and have all the spare or needed parts.. ----- Original Message ----- From: "VeeAthreePL" To: Sent: Thursday, May 29, 2003 2:23 PM Subject: [Antennas] Refurbishing old TH6DXX > Has any one complete listing of bolts and nuts for TH6DXX? > Are those "stainless steel" bolts and nuts from Home Depot are really > stainless steel? > Suggestions? > > Andy VA3PL > > - - - > > Your moderator for this list is: > Larry Wilson KE1HZ antennas-owner@mailman.qth.net > _______________________________________________ > Antennas mailing list > Antennas@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/antennas > From sastrup@online.no Fri May 30 05:21:13 2003 From: sastrup@online.no (Sven Arne Astrup) Date: Fri, 30 May 2003 04:21:13 -0000 Subject: SV: [Antennas] Refurbishing old TH6DXX References: <3ED5BD9B.0000B7.45288@ns.interchange.ca> Message-ID: <00b301c32662$e9162920$ab4bfea9@la6kjbbs> Hallo Andy! Follow this link: http://f5ad.free.fr/ANT-DOCS_Menu.htm 73 de Sven LA6KJ ----- Original Message -----=20 From: VeeAthreePL To: Sent: Thursday, May 29, 2003 7:23 PM Subject: [Antennas] Refurbishing old TH6DXX > Has any one complete listing of bolts and nuts for TH6DXX? > Are those "stainless steel" bolts and nuts from Home Depot are really=20 > stainless steel? > Suggestions? >=20 > Andy VA3PL >=20 > - - -=20 >=20 > Your moderator for this list is: > Larry Wilson KE1HZ antennas-owner@mailman.qth.net > _______________________________________________ > Antennas mailing list > Antennas@mailman.qth.net > http://mailman.qth.net/mailman/listinfo/antennas >=20 >=20 >=20 From Punkymcd@pacbell.net Fri May 30 23:48:56 2003 From: Punkymcd@pacbell.net (Punkymcd@pacbell.net) Date: Fri, 30 May 2003 15:48:56 -0700 Subject: [Antennas] Super Tee Balun picture References: <20030530080124.28E8E328A2C@mailman.qth.net> Message-ID: <3ED7DFD8.9000401@pacbell.net> Does anyone have a picture of the physical winding of the Super Tee antenna tuner. i.e. a picture of drawing of the BLN-43-202 (BN-43-202) Thanks Don, W6OA