Hi all,I am shortly replacing my short vertical antenna with a newer
version....This consists of a 12 foot diameter 6 spoke top hat with
perimeter wire above a 70uh edge wound inductor ex broadcast gear...I
should know the answer to this but I have forgotten some of my previous
experience with my short 160 meter antennas
I have mounted the structure on a piece of 12 foot masting and run a
few radials to check where the structure resonates....It works out in
that configuration as resonant around 1.940 khz..
My question......I am going to mount this top loading on a 50 foot mast
over 40 150 foot radials replacing the current vertical.....With
resonance showing 1.940 khz at 12 feet high how much do you think the
resonance will drop when the top loading is at 50 feet? The top VK band
edge is 1.875khz....I only use the CW portion of the band to 1.843 so as
long as resonance doesn't drop below that I am happy....I will be using
the usual series inductor at the base of the vertical for fine tuning
and matching to the LDF 450.....That inductor is only 10 turns 6 inches
dia 5/8 inch copper tubing....
Depending on work schedules I am hoping the crew will be here in the
next week or so to do the work..
Any time anyone wants details of my 160 meter antenna don't hesitate to
ask....I will post construction pictures and the actual antenna on my
web page as soon as we get the work completed...
73....Bob VK3ZL..
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