[Antennas] RE: Antennas Digest, Vol 38, Issue 7
BILL CROGHAN
billcroghan at earthlink.net
Mon Mar 12 21:58:53 EST 2007
A choke across the feed point would not bleed the voltages from the antenna
due to static buildup, but a Choke from each side of the feed point to a
good ground would We use large chokes to feed AC to tower light systems in
AM broadcast antennas that might work to bleed the DC buildup. Typically
these are 50 or so turns of wire on a 3-4 inch form. The high inductance
has little or no de-tuning affect on the RF but provides a good drain for
DC, and almost no blockage for the 60 HZ AC feeding the tower lights.
Remember you are attempting to bleed off the buildup before it reaches arc
over potential (Lightning) rather than suppress the high voltage spikes
produced when the arc occurs.
Bill
WB0KSW
> -----Original Message-----
> From: antennas-bounces at mailman.qth.net [mailto:antennas-
> bounces at mailman.qth.net] On Behalf Of antennas-request at mailman.qth.net
> Sent: Monday, March 12, 2007 1:01 AM
> To: antennas at mailman.qth.net
> Subject: Antennas Digest, Vol 38, Issue 7
>
> Send Antennas mailing list submissions to
> antennas at mailman.qth.net
>
> To subscribe or unsubscribe via the World Wide Web, visit
> http://mailman.qth.net/mailman/listinfo/antennas
> or, via email, send a message with subject or body 'help' to
> antennas-request at mailman.qth.net
>
> You can reach the person managing the list at
> antennas-owner at mailman.qth.net
>
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of Antennas digest..."
>
>
> Today's Topics:
>
> 1. test (Jan)
> 2. assembly instructions (Jan)
> 3. Re: assembly instructions (Ray Brown)
> 4. rf choke (G B)
> 5. Re: rf choke (Ray Brown)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Sun, 11 Mar 2007 16:03:33 +0100
> From: Jan <antennas at pa4jj.nl>
> Subject: [Antennas] test
> To: antennas at mailman.qth.net
> Message-ID: <45F41A45.2080007 at pa4jj.nl>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> testing
>
>
> ------------------------------
>
> Message: 2
> Date: Sun, 11 Mar 2007 16:17:32 +0100
> From: Jan <antennas at pa4jj.nl>
> Subject: [Antennas] assembly instructions
> To: antennas at mailman.qth.net
> Message-ID: <45F41D8C.9090800 at pa4jj.nl>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> Hello
>
> I recently purchased a second hand Warc beam made bu Finnish Antennas.
> However, the person I bought the antenna from cannot find the assembly
> instructions.
>
> Anyone on this reflector who can give me the dimensions.
> The boomlength of this older model is (in meters) 3.8 M
>
> (The newer version of this model has a boomlenght of 4 M.)
>
> Any info would be appriciated.
>
> 73's
> Jan
> PA4JJ
>
>
> ------------------------------
>
> Message: 3
> Date: Sun, 11 Mar 2007 13:54:20 -0600
> From: "Ray Brown" <kb0stn at sbcglobal.net>
> Subject: Re: [Antennas] assembly instructions
> To: <antennas at mailman.qth.net>
> Message-ID: <00f101c76417$0f7b1b20$4201a8c0 at gateway.2wire.net>
> Content-Type: text/plain; charset="iso-8859-1"
>
> ----- Original Message -----
> From: "Jan" <antennas at pa4jj.nl>
>
>
> > I recently purchased a second hand Warc beam made bu Finnish Antennas.
> > However, the person I bought the antenna from cannot find the assembly
> > instructions.
> >
> > Anyone on this reflector who can give me the dimensions.
> > The boomlength of this older model is (in meters) 3.8 M
> >
> > (The newer version of this model has a boomlenght of 4 M.)
> >
> > Any info would be appriciated.
>
> Greetings, Jan... did you try their home page for any information?
> http://www.oh2u.com/finnishantenna/products2.htm lists several models,
> which I cannot determine which would be yours from what you stated,
> sorry. Here's a list of what's on that web page...
>
>
> Oy Finnish Antenna Ltd.
> Catalogs
>
> Product Catalog
> JP 7-2 Shorty product sheet
> JP Current Choke-H product sheet
>
>
> Manuals
>
> JP2000 Manual
> JP-Tribander Manual
> JP7-2 Manual
> JP7-2 Shorty Manual
> JP20/17 6L Duobander Manual
> JP6m6 Monobander Manual
> JP10-2 Shorty Manual
>
>
> Dimensions (Excel sheets)
> 40M2L Shorty
> JP7-3
> JP30-2
> JP14-4
> JP21-4
> JP28-4
>
> Other than this, there is very little information out on the Internet
> about any Finnish antennas. Good luck, OM.
>
> _Ray_ KBXSTN
>
>
>
>
> ------------------------------
>
> Message: 4
> Date: Sun, 11 Mar 2007 21:06:14 -0400
> From: "G B" <microsys at alltel.net>
> Subject: [Antennas] rf choke
> To: "Antennas" <antennas at mailman.qth.net>
> Message-ID: <OLEMLLLENPOJJLABJGKJCEEIDCAA.microsys at alltel.net>
> Content-Type: text/plain; charset="iso-8859-1"
>
> I am starting my 'monster' horizontal loop, about 3 wavelengths at 160M
> averaging about
> 70' high.
>
> I am very concerned about the certainty of high induced voltages on the
> antenna during
> thunderstorms. I have heard that I could add an rf choke across the open
> wire line
> junction up at the antenna end.
>
> I have never done this, and wonder what kind of choke would be appropriate
> for
> 160M thru 6M???
>
> 73's
>
> Glen K4KV
>
>
>
>
> ------------------------------
>
> Message: 5
> Date: Sun, 11 Mar 2007 20:30:02 -0600
> From: "Ray Brown" <kb0stn at sbcglobal.net>
> Subject: Re: [Antennas] rf choke
> To: "Antennas" <antennas at mailman.qth.net>
> Message-ID: <030101c7644e$56adb5c0$4201a8c0 at gateway.2wire.net>
> Content-Type: text/plain; charset="iso-8859-1"
>
> ----- Original Message -----
> From: "G B" <microsys at alltel.net>
>
> > I am starting my 'monster' horizontal loop, about 3 wavelengths at 160M
> > averaging about 70' high.
>
> THREE wavelengths... hmmm. There's a local ham that put up a 2 wave
> at 80m antenna during Field Day, and it worked out quite well. I believe
> that it was oriented in a square and it did well I'm just trying to
> envision
> what a 3-wavelength SkyWave would do.
>
> > I am very concerned about the certainty of high induced voltages on the
> > antenna during thunderstorms. I have heard that I could add an rf choke
> > across the open wire line junction up at the antenna end.
> >
> > I have never done this, and wonder what kind of choke would be
> > appropriate for 160M thru 6M???
>
> I don't know about any choke that would bleed voltages down like that.
> I don't remember for sure what my friend used, if it was a 1:1 or 4:1
> balun
> on the loop. I'd also think about a couple of PolyPhaser supressors. But
> you're out of my league here...
>
> _Ray_ KBXSTN
>
>
>
> ------------------------------
>
> ______________________________________________________________
> Antennas mailing list
> Home: http://mailman.qth.net/mailman/listinfo/antennas
> Help: http://mailman.qth.net/mmfaq.html
> Post: mailto:Antennas at mailman.qth.net
>
>
> End of Antennas Digest, Vol 38, Issue 7
> ***************************************
More information about the Antennas
mailing list