Date: Tue, 7 Nov 2017 12:21:53 -0600
From: "Jeff" <keepwalking188@ac0c.com>
To: "Steve Wright" <stevewrightnz@gmail.com>, <amps@contesting.com>
Subject: Re: [Amps] Alpha 87 (not 87A)
<It's true that a mistuned amp can generate plenty of harmonic energy
content. Many years ago I was running a 76PA into a resonant but extremely
narrow banded 160m antenna. There was a contest going and so I was bumping
around the band. You get tired of tweaking the knobs in that case so I just
backed off on the power and ran around the bands roaming a frequency that
covered roughly 3:1 or less SWR match. Over the following week I collected
an OO card and a few FYI email from guys nice enough to mention that my CW
2nd harmonic was being copied in the low end of the SSB 80m band.
I've moved since then and have better antennas. But a feature of all the
new stuff is a notch on the 2nd harmonic if it's in a ham band.
73/jeff/ac0c
www.ac0c.com
## The one time I had a issue with harmonics was.... a local 1.5 miles away
was TX on 160M SSB... on 1952.5..into
a MULTIBAND VERTICAL..running 100w. I could hear his 2nd harmonic on
3905... which happened to be the freq I was on.
## W8JI did say he had complaints of folks being able to hear the 2nd harmonic
of his 160m CW signal... as in
loud and clear. Being a 160m monoband array, I was surprised, but its a big TX
array. His fix was to install a
stub..right at the feedpoint. That was years ago.
## I have never heard of issues with harmonics of a 80m monoband ant coming
out on 40m. Nor 40m signals, from a
40m monoband ant... coming out on 20m. Nor a 20m signal, being heard on 10M.
## of course, if you are on 3650 to 4000, any 2nd harmonic will be above
7300.... so nobody to complain anyway.
Ditto if you TX above 7175 khz.... u end up above 14.350.
Later... Jim VE7RF
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