I have that Antenna.
The top loading coil and whip and hat was to enable the other coils and
tubing to reach down and resonate on 75m/80m band. Expect just the top
coil and its whip to be higher in frequency than 80m and maybe
considerably.
If I can lay hands on mine, which was removed so the rest of the antenna
could fit a certain storage place, I could set up a test with my MFJ
Antenna analyzer, feeding it against a ground laid radial.
On the web you may find discussions that could guide you of Phil Salas's
43 foot short vertical plus its coil he added. Also, any of the Sevick
papers on short verticals. Probably in the QST archives.
Remember, that you double the size of the coil to get the next lower
harmonic band, if the whip et al does not change. Thus, you could make
estimates, extrapolating from articles of other short verticals.
-Stuart Rohre
K5KVH
|