[FARC] Re: FARC Digest, Vol 37, Issue 9

[Howard W3CQH]

> Message: 2
> Date: Wed, 18 Jul 2007 17:37:25 -0400
> From: "Kirk Talbott" <KirkTal7237 at msn.com>
> Subject: Re: [FARC] The best antenna for a new ham
> To: "Frederick, Maryland ARC" <farc at mailman.qth.net>
> Message-ID: <BAY101-DAV767ADFA9FAA8D432ED2A8A6FA0 at phx.gbl>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Tnx Joe for the great antenna info.  It's good to know what works and I'd 
> like to relate for the benefit of others what I've tried that doesn't.
>
> Beware the "shortened" dipole.  I don't have a lot of tall trees or the 
> yard space for a very a long dipole antenna. The plethora of ham magazines 
> that arrive in the mail are full of ads and ideas for "shortened" dipoles 
> or wire
> antennas much shorter in length than the standard length of a dipole for a 
> particular band.
>
> I took the bait and bought a 20 meter "shortened" dipole which is 20 ft. 
> long with two small coils.  This particular antenna carries the label of 
> QRP antenna and the instructions indicate that it is for use with 150 
> watts or
> less.  From a diagram in a book, I assembled my dipole in a "sloper" 
> configuration, the high point attached to my TV tower about 12 feet up. 
> Per the diagram in the book, the low end of the sloper is attached to a 1 
> foot
> wooden stake hammered in the ground.  The dipole is center fed with RG-8X 
> coax at a 90 degree angle to the wire, or nearly so.
>
> This was an easy, neat, and compact antenna installation project.  The 
> only problem is that it doesn't work. I would say it works marginally on 
> PSK and RTTY because it is actually cut for the CW portion of the 20 meter 
> band. I
> have made a few contacts with it.  It doesn't work at all on 20 meter SSB 
> phone and I've made no contacts with it. The instructions did indicate 
> that an antenna analyzer would probably show that it would need trimming 
> to
> operate higher in SSB phone portion of the 20 meter band, however, since 
> it didn't work very well with PSK or RTTY for which the dipole was 
> originally cut, trimming it couldn't possibly have made it better.
>
> So, the moral of the story is an old one.  The antenna was $39 plus 
> shipping and it looked too good to be true.  It wasn't.
>
> 73
> KB3ONM
> Kirk
>
>
> ----- Original Message ----- 
> From: "Joseph M. Durnal" <joseph.durnal at gmail.com>
> To: "Frederick, Maryland ARC" <farc at mailman.qth.net>
> Cc: "MADXRA's Friends&Members" <madxra at madxra.org>
> Sent: Tuesday, July 17, 2007 11:26 AM
> Subject: [FARC] The best antenna for a new ham
>
>
>> Short answer: A 40 meter dipole
>>
>> Short why: Because it works great on 15 meters too
>>
>> When I ordered my Elecraft K1 2 band Transceiver kit, I had to decide 
>> which two bands I wanted it to come with.  After a lot of thought, I 
>> decided on 40 & 15 meters, for two reasons.  First, 21 MHz is the third 
>> harmonic of 7 MHz, making a 1/2 wave dipole for 40 meters a 1 1/2 wave 
>> dipole on 15 meters, a 50 ohm match that will even have a little bit of 
>> gain.  Second, the propagation properties of 40 & 15 meters complement 
>> each other.  While 40 is great for local and regional communications, 15 
>> is a great DX band, but that doesn't mean that you can't work DX on 40, 
>> or work state side contacts on 15.  I  also thought about the 11 year 
>> sunspot cycle, and sadly, right now,
>> there are few sunspots, which isn't so good for 15 meters, but it is rare 
>> for the maximum usable frequency not to get up above 7 MHz.
>>
>> I've been asked by a few hams new to HF about what they should do for 
>> their first antenna.  I often answered generically, "it depends on what 
>> you want to do".  But often new hams don't have a predefined idea of what 
>> they want to do, but want to try different things.  After the
>> long hours of deciding the bands I wanted in the K1, I figure I could 
>> apply the same logic to a first antenna recommendation for a new ham.
>>
>> Building a 40 meter dipole (on the cheap):
>>
>> 68 feet of wire (14 ga +/- is fine, copper is best, no insulation 
>> required)
>> 3 insulators
>> length of light rope
>> length of coax
>>
>> 1.  Locate two supports at least 70 feet apart
>> 2.  Cut wire in two equal lengths
>> 3.  Attach one end of each leg to the center insulator
>> 4.  Solder the coax center conductor to one leg of the dipole and the 
>> shield to the other. It is also advisable to provide some strain relief 
>> which can be accomplished by wrapping the feedline once around the center 
>> insulator and securing with a cable tie-wrap.
>> 5.  The connection can be weather proofed with silicone sealant
>> 6.  Attach the other end of each leg to an end insulator, each leg should 
>> be about 33 feet, the excess wire can be folded back and wrapped around 
>> the leg and/or trimmed.
>> 7.  Attach a length of light rope to each end insulator and tie to 
>> supports located in step one.
>>
>> Some notes:
>> - Dipole legs don't need to be perfectly straight or horizontal.
>> - Do not put any part of the antenna system over, across or near electric 
>> lines.
>> - Keep the ends of the antenna at least 8 feet above ground to prevent it 
>> from being a hazard to those walking by.
>> - Insulators can be made out of just about anything that doesn't conduct 
>> electricity.
>> - A commercially made 40 meter dipole can be bought for $35 or so,  most 
>> will require a little trimming to make them resonate.
>>
>> Please save this note and pass it on to anyone seeking advice on a good 
>> first antenna, feel free to improve it in any way you wish.
>>
>> 73 de Joe NE3R

=============
Kirk - If you are still having problems with the dipole - I will loan you my 
6 band 80m - 6m, Mobile antenna system, that you can mount on a pole.  The 
only thing that you will have to do is make a small harness to feed it with 
RG58u cable and some PL259 connectors...
73's de Howard W3CQH
1-240-793-6736 - cell