Good Point. I also thought that the initial SWR was good for a dipole but
perhaps it was not high or has a hairpin match. I asked where the new
resonant point is and did not get an answer. If it just moved I would
readjust the tips. I also wonder if the test coax and balun are the same
and in the same configuration (running 90 degrees from the center of the
element) as the permanent.
BTW his initial post is here:
http://lists.contesting.com/pipermail/towertalk/2018-March/160150.html
John KK9A
Sent via the Samsung Galaxy 7 edge, an AT&T 4G LTE smartphone.
AC0DS Wrote:
Dave …
I’ve been following this mystery since your first post. Lots of very
experienced people contributing (including yourself), so I’m sure the
solution will surface shortly.
One thing that I just now recalled. I no longer have your initial post
handy, but remember that the initial test with the dipole hung up in free
space away from the tower was very good. In fact, so good that it seemed
suspicious. I think the SWR was something like 1.1 over the entire 40
meter band?
Don’t know what height the dipole was, but even a perfect dipole won’t be
that close to 50 ohms at most heights. And, would expect to see some
variation over the band.
Questions:
How long is the coax and what type?
You said you had a balun at the feed point. I assume it is a choke with
the coax wound around ferrite?
How were you measuring the SWR?
One possibility is that you perhaps had some unintentional losses (or
measurement error) in your first test that went away when you mounted the
dipole to the tower?
73 Craig AC0DS
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