Several weeks ago I mentioned here on the reflector that I had received some
reports of a nasty problem with key clicks (tnx W8UVZ, VE3DO, and others).
I had some problems replicating the problem but, to make a very long story
short, I have isolated the problem to my 4 sq array. I had no problem with
clicks on my 1/4 elev feed vertical. When I transmitted into the 4 sq on
1825, I could make the clicks occur with about 1200w. Also, when the clix
did occur, my SWR back at the shack (abt 800' away) suddenly jumped from
about 1.5 to about 1.8 (I hadn't noticed this until today). I also noticed
that when I moved down to the bottom of the band it took more power to make
the clicks occur. When I went up to 1870 I could not make the clicks occur
at all.
My 4 sq array is made up of ground mounted vertical wires (each with its own
independent radial system) suspended from catenary lines hung on a 190'
tower. When I modeled the array I noticed that the tower degraded the f/b
performance of the array about 6 or 8 db. The modeling showed that tuning
the bottom 100' of the tower made it transparent to the array. So I decided
to tune the tower with a side mounted #14 copperweld wire spaced about 12"
from the tower extending from 4' above ground to the 100' level. I used a
fairly wide spaced air variable cap (it takes about 83 pf to resonate at
1825) at the bottom of the tower to resonate the wire. I had suspected the
tuning circuit to be a possible culprit all along (probably from a flashover
in the tuning cap).
To shorten this already too long story, when I short the tuning cap, the key
click problem disappears altogether. Careful inspection of the cap shows no
signs of flashover. That said, there is flashover taking place somewhere in
the wire/cap tuning circuit or perhaps in the tower hardware itself. I will
continue to investigate. In the meantime, the tower tuning circuit is
disabled and the clicks problem is solved.
73...Dave
W0FLS
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