At XA5T over the ARRL DX CW contest, we ran into a problem which
perplexed us to the point where we had to install our 160m inverted V on
a completely different tower.
On a 90' Rohn 25 tower, with 3 sets of guys (I think they are insulated,
but don't remember for sure) we have a Cushcraft 204BA on top, a 2 el 40
side mounted at 70' more or less, and an 80m inverted V at 50' more or
less. The 160m inverted V, mounted a couple of feet above the 2 el 40,
showed SWR at 1.9 at 1830 on an AEA analyzer, but the phase warning
popped up each time we measured it. We moved it up or down a few feet
several times, ran the legs a little flatter to other towers at heights
varying from 15' to 40', and tried it as a sloper from the top of the
tower to the ground. Each time the SWR was within reasonable limits,
but the AEA analyzer phase warning always appeared. When measuring the
160 with an MRJ-259, the impedence dial always measured well above 100
ohms, no matter which configuration we used. With all this going on the
tower, the 2 el 40 showed abov 3:1 SWR consistently, but the 80 mtr wire
and the 204BA always checked good. Various configurations of the 160
wire had, alternately, a 1:1 balun which checked good, or a porcelain
dog bone.
Ultimately, after moving the 160 wire countless times with no success,
we moved it to the 50' level of a 55' twr with a TH6 on it a couple of
hundred feet away. There it checked good and played well, the TH6 was a
hose, and all the remaining antennas on the 90' tower, including the 2
el 40, performed as advertised.
We conclude we had a phasing problem of some sort. We would like to run
the 160 wire from a higher elevation, but need to resolve the problem.
We could attach it near the top of an 80' tower which contains a dual 15
mtr array, but, sadly, have no more towers left after that with which to
experiment. Any ideas?
Regards,
Madison
w5mj
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