from HB9ASB
Hello Bob,
I'm using a helical vertical for more than a year and it works fine.
The lower part (7m) is a PVC irrigation pipe (11cm Diameter) the upper
part a Kevlar fishing pole (8m). I've wound about 350m of Liz wire on
it. Top load is a 60m long wire going up to 18m and then down to 8m,
zigzag over my 30*40m property. Self resonance of the whole thing is
around 170 kHz and I match it to the coax via an autotransformer (abt.
1mH), wound on a plastic waste-paper basket.
For comparison I've built exactly the same antenna a few meters away but
with a straight wire instead of the helical. The helical was always 3 or
more dB's better, on transmit and on reception.
I think the helical is good for some more dB's if you can make the
diameter larger (a handling problem, hi).
73 de Toni
Bob RIESE schrieb:
Has anyone done anything with a continuously loaded vertical and top hat.
40 Ft of large diameter plastic pipe wound with copper wire would be a
rubber duckie on LF, the only problem I see would to keep it from acting
like a Tesla Coil
Bob K3DJC
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