N2EA writes:
>
> If it were balun connections, why would
> it manifest only on 15 meters?
I would be more inclined to suspect a problem with the beta
insulators and/or the driven element insulator. Although
they are common to all three bands, the RF voltages are
very different at those points (particularly the beta match)
on each of the three bands. If one of the insulators is
cracked or has a small "pin hole," perhaps from lightning
the RF stress could be causing heating, etc.
Given that a TH3MK3 would be quite a few years old, I
would be very tempted to order a complete set of insulators
for the driven element and beta match. In fact, the beta
match was completely redesigned in the TH3MK4 to eliminate
the insulators ... anyone know why?
73,
... Joe, K4IK
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