It would be interesting to know how the antenna would have performed without
feedline distortion by using with a choke-balun, however you did the test
correctly following the manufacture's instructions. You were testing and not
optimizing the antennas. I wonder if the stations that claim to be doing
well with these antennas are isolating their feedlines. Mosley's PRO-57B
claim of 8.5dBd gain on 20m with only a 24' boom is incredible
Subject:Re: [TowerTalk] If you had a choice
From:"Ward Silver" <email@example.com>
Date:Tue, 16 Oct 2012 11:13:31 -0500
That is correct. We used a Force-12 1:1 bead balun (i.e. common-mode choke)
on all of the other antennas, including the reference dipole, except for the
KT-34XA which came with a 4:1 balun/transformer.
There are a number of stations with good signals, using Mosley beams. Most
notably, K4RO has a pair of them and does quite well. He also has an
extraordinary ridge-top location and has taken great pains to locate the
antennas and towers to take advantage of that location. As in real estate -
location, location, location. I used a Mosley Classic 36 at W0EEE for years,
myself, with pretty good results.
The Mosley manual we had with the loaned PRO-57B (I think it was a B model)
gave specific instructions how to construct the coax pigtail and said
specifically not to use any additional devices at the feed point. It has
been a long time since we did the tests (11 years, I think) and it is quite
likely that the manual has been changed to recommend a common-mode choke. I
would applaud that change as good practice. Feed line interaction could have
certainly affected the results on one or more bands. We followed the rule of
doing what the manufacturer said to do.
73, Ward N0AX
Date: Tue, 16 Oct 2012 10:14:21 -0400
Subject: Re: [TowerTalk] If you had a choice
Was this test run with no choke at the feed point of the Mosley and the
other antennas in your test had one?
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