In a message dated 2/20/01 7:22:45 AM Pacific Standard Time,
w2up@mindspring.com writes:
> I purchased this TH7 used about 2 years ago. I was told it was just
> a few years old and appeared to be in excellent condition. I am
> using a Palomar BA-2000 balun with it.
>
> Recently, the antenna has developed a higher than usual SWR on
> 15 and 20 meters, running between 2:1 and 2.5:1. It is just about
> flat across both bands. 10m seems to be fine. Has anyone else
> had similar problems? Is the most likely source the traps on one of
> the driven elements? Comments appreciated.
Sounds like a trap problem. Is the swr constant across the whole band?
With 2 driven elements, one DE might work and the other have a problem.
Have you put an antenna analyzer on the feedpoint? That's the first thing
you need to do. If the antenna's okay, start working down the feedline to the
shack. If you're measuring the swr at the shack, make sure you go to the
feedline directly when you measure. MANY shack 'antenna' problems turn out to
be bad jumpers, bad switch, etc.
If this was a feedline problem, you'd have high swr (5:1 or so)
everywhere.
Cheers, Steve K7LXC
Tower Tech
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