Kevin writes:
> with respect to the burning on the plate choke: yup it's only
> in certain areas. So the comments about vhf parasitics are
> probably right on, if that's a key indicator.
>
> The 22 ohm suppressor R's physically looked okay, but I'll
> be sure to measure them.
These two observations point not to parasitics but an attempt
to operate the amplifier on a band for which it was not designed
perhaps 17, 12 or 11 meters. Burning in certain areas of the
plate choke indicates high voltage at that point, probably due
to a resonance. That often happens to older amplifiers not
designed with "WARC" band operation in mind.
Some very good examples are the MLA-2500 which had a resonance
near the 17 meter band and the Alpha 76 series of amplifiers
that intentionally had a choke resonance around 25 MHz which,
while it prevented operation on 11 meters, happens to prevent
the amplifier from being used on 12 meters.
73,
... Joe, K4IK
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