It's been interesting to read the various comments and observations in
the recent thread about matching a tower and using it as a radiator.
I am in the throws of finishing up an HF tower at a new QTH located
out in the country (finally getting away from 80'x120' city lots after
all these years).
My dilemma is this...the new tower is a 130' rotating Rohn 55. The
rotor and stationary set of guys is at 40'. There are guy rings at
80' and 120'. I have TH7's stacked at 41', 81', and 121' and a Mosley
3 element 40 meter yagi at 130'. The elements on the Mosley are
insulated so I don't believe it will contribute to any top loading.
However, with the TH7 at 120', my guess is that the tower is
electrically more than 90 degrees (maybe 100 or 110?).
Since the tower rotates above the 40' level, 40' would be as high as I
could attach any sort of gamma rod. If I use elevated radials at 10',
that would make the gamma rod length only 30'. Does anyone have any
thoughts on whether or not such a short gamma rod might work? Are
there issues of efficiency (or inefficiency) involved with a short
gamma rod? Would I be better off putting up something like a delta
loop??
Thanks and 73,
Dave
W0FLS (formerly WA0FLS)
CSUS04@email.mot.com (that's CSUS ZERO FOUR)
P.S. Had a great time operating the 160 mtr contest last weekend at
N0NI's. I thouht the overall discipline/use of the dx window
was the best I've seen in recent years...condx weren't bad
either. What happened to the Carribean??
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