I currently switch my 90 foot toploaded vertical between 40, 80, and 160
meters using vacuum relays at the 30 and 60 foot point. They are latching
types, so they just need to be pulsed. There are coils across them which
resonate out the several pf of stray capacitance and also give DC continuity
for static drain (and in the case of the 30 foot relay, the coil signal to
the 60 foot relay). I run full power on 80m, but have had some problem with
overheating of the 60 foot relay. Conclusion: it is workable but may be
problematical. It was a fair amount of work to build the switch boxes. I
am still trying to figure out how to keep condensation out of them; maybe I
will pot the whole assy someday.
Rick Karlquist N6RK
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