My TH7 has exhibited high SWR, especially at high power, when it's
wet. On my antenna, some of the DE trap cover drain holes were either
misaligned or missing.
The trap end covers on the outboard end of the traps, that is the end
furthest from the boom, should have drain holes. If not, pull the
trap cover off or at least away from the body of trap before
carefully drilling a pilot hole and then enlarge to 1/4 inch. The
hole should be on the tapered part of the cover where it meets the
larger circumference that fits onto the trap body. (No drain holes
are on the covers on the inboard trap ends.)
Even if current production does not have these end cover holes, I
would add them. This is something to be considered for trap end caps
on any brand of trapped antenna.
It's also a good idea to make sure that the screws under the trap
inboard end cover are hand tight.
At final assembly, the trap drain and end cover holes should all be
in the same plane and aligned directly towards the ground.
73 - Steve WB6RSE
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