Topband: New antenna

[robert briggs]

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..