Just built a wire vertical dipole (Lazy H style) yesterday for 80m
(very similar to the one shown on EI7BA's web site here ). Since I
am feeding the antenna asymeterically I knew an RF Choke would be in
order. EI7BA recommends an FT240-61 with 12 turns of RG-58. Not
having the recommend ferrite at hand, I proceeded to homebrew a choke
out of a large diameter (~7") plastic coffee can and 20 turns of
closely spaced RG-58 well secured.
This apparently isn't good enough?? When testing at the antenna with
my MFJ it is "spot-on" correct just like the model and resonant at
the design freq. of 3.830. However when using the homebrew RF choke,
resonance is just above 4 MHz. I did test without a choke at all and
resonance was much much higher.
Is this not enough choke at this frequency?
Thank you,
Jim...
N5SPE
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