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Weatherproofing helix feeds.



After some success with AO-40 reception in the past few days, I mounted my 
helix outside with mixed results.

The helical winding rests on insulating PCB mounting pillars pushed into the 
half inch square Aluminium boom. This works fine and rain cannot electrically 
connect one turn to the next. 

However at the first sign of rain the antenna detuned. This turned out to be 
due to water droplets bridging the gap between the ground plane and the 
quarter turn matching section.

Any practical suggestions  from the reflector on how to waterproof this 
without de-tuning?  I've looked at a few web sites, but you lucky people all 
seem to be blessed with sunny climates.
I suspect silicon sealant may change the dielectric constant between the 
matching section and the ground plane giving the same detuning effect as the 
rain.

Thanks


David G0MRF
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