[TowerTalk] AV-640 (was GapChallenger ComparisonTesting Studies)

[Jim Hargrave]

>> So far, I have outlined several differences between 2 types of Windom and
>> the AV-640, enough to justify NOT calling it a Windom.

>> Wouldn't you agree?


Dan,

I pass. I have never owned an AV-640, so I cannot offer a qualified opinion.

I only pointed out that an antenna that is off center fed is commonly
referred to as a "Windom". We normally think in terms of horizontal.
However, I see no reason the same principal could not be applied vertically.

Perhaps I should start calling my 17M antenna a "Vertical Windom"
Its a 1/2 wave vertical consisting of a 3/8 wave whip mounted 6ft above the
ground
on a steel pipe. Its fed at the top of the pipe (base of the whip).
I use homebrewed link coupling to a 50 ohm coax.

Since it off centered fed, I guess it the meets the same principal...

    73 de Jim
     W5IFP

> -----Original Message-----
> From: towertalk-bounces at contesting.com
> [mailto:towertalk-bounces at contesting.com]On Behalf Of Dan Schaaf
> Sent: Monday, April 26, 2010 5:45 PM
> To: Tower and HF antenna construction topics.
> Subject: Re: [TowerTalk] AV-640 (was GapChallenger ComparisonTesting
> Studies)
>
>
> Jim
>
> Exactly !!!
>
> And the antenna book also mentions that the single wire feed
> Windom produces
> RFI in the shack and it works against a ground. And the single wire feed
> line also is a radiating element.
>
> Not a whole lot different than an Inverted L in both appearance and
> operation.
>
> The Carolina Windom reduces the RFI in the shack by splitting the
> windom at
> the feedpoint and feeding with coax and a matching balun.
>
> Between the single wire feed windom and the dual wire feed
> windom, the dual
> wire feed most likely resembles the HyGain 640 vertical. With the
> important
> exception of the specified lengths on the horizontal radiator.
>
> Both versions have almost a unidirectional pattern as a
> horizontal polarized
> antenna. Many lobes, unlike a dipole which has 2 distinct lobes broadside.
>
> Once again, the AV-640 is a Vertical or Marconi antenna. It
> differs from a
> typical vertical monopole in that it is 3/8 wavelength radiator, not 1/4
> wave radiator.
>
> I suppose that one could call a vertical monopole with short
> ground radials
> also a vertical Carolina Windom. But definitely not a Windom as it was
> originally designed with a single wire feed and no break in the
> horizontal
> wire.
>
> And my AV-640 does NOT provide RFI in the shack.
>
> So far, I have outlined several differences between 2 types of Windom and
> the AV-640, enough to justify NOT calling it a Windom.
>
> Wouldn't you agree?
>
> Dan Schaaf
> K3ZXL
> "In the Beginning there was Spark Gap"
> www.k3zxl.com
> ----- Original Message -----
> From: "Jim Hargrave" <w5ifp at gvtc.com>
> To: "Tower and HF antenna construction topics." <towertalk at contesting.com>
> Sent: Monday, April 26, 2010 5:51 PM
> Subject: Re: [TowerTalk] AV-640 (was GapChallenger ComparisonTesting
> Studies)
>
>
>
> "Windom" Antennas.
>
> http://www.packetradio.com/windom.htm
>
> http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=12135
>
> A little history:
>
> http://hamwaves.com/cl-ocfd/history.html#early
>
>
> The 1956 ARRL Radio Amateur handbook calls them: "Windom" or
> OFF-Center Fed
> Antenna"
> Page 343 has a description and shows two methods of feed. One is
> fed with a
> single
> wire as the original antenna and the other is with a 300 ohm line
> and Balun
> coils
> to a coax which is sometimes called a "Carolina Windom".
>
> They have been called "Windom" at least for the 56 years I have
> been a ham.
>
>    73 de Jim
>      W5IFP
>