[TowerTalk] Vertical question

[john nistico]

So I added a ground rod and a few extra radials to my 80 vertical and it raised the frequency from 3.650 to 3.890 wondering if I should lengthen it?

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From: TowerTalk <towertalk-bounces at contesting.com> on behalf of Jim Brown <jim at audiosystemsgroup.com>
Sent: Wednesday, March 17, 2021 1:40:38 AM
To: towertalk at contesting.com <towertalk at contesting.com>
Subject: Re: [TowerTalk] Vertical question

On 3/16/2021 2:50 PM, Richard (Rick) Karlquist wrote:
> What has always worked for me is to simply turn down the
> RF gain and/or change the AGC threshold such that there
> is no AGC action.  It is then possible to switch back and
> forth while listening and hear the increase or decrease in
> loudness.  This does of course require a signal on the air
> to use.

Yes. When I first moved here in 2006, I had both the Tee vertical
(although not as tall and not as many radials) and a horizontal dipole
at about 110 ft. I did exactly what you suggest, turning down the RF
gain or turning off AGC, depending on what the rig provided. I did that
for a year or two, learning that on some signals one or the other might
be louder, but, especially after adding radials and making it taller,
the Tee nearly always won. But just as with RBN 15 years later, you've
got to do a lot of A/B switching to take QSB into account. That dipole,
even at 110 ft was electrically low on 160, making it a relatively
inefficient antenna with relatively little energy at low vertical angles
and max gain at higher angles, while the Tee has very little high angle
radiation, concentrating it at low angles.

> The problem with RBN is that is measures S/N, not absolute
> amplitude.  The noise floor is not necessarily the same at
> two different frequencies or times.  In this case S/N doesn't
> correlate with signal strength.  Possibly you could fix this
> by swapping the frequencies every other time.

Yes. I take that into account by TXing TEST K9YC a half dozen times on
slightly different frequencies, then switching to TEST KU6W a half dozen
times a kHz or so apart, and repeating that process at least a dozen
times, QSYing slightly so RBN will spot me again. After taking the data,
I average the reports for each station for each antenna. And I always do
this on a part of the band with little or no activity (which is pretty
easy on 160 CW during the week). My data now consists of average signal
reports for each antenna from 15-20 different stations, which I then
sort by azimuth.

73, Jim K9YC



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