[Amps] HF2500 - 15 meter problem
Paul Christensen
w9ac at arrl.net
Wed Aug 24 19:30:57 EDT 2022
Steve,
Closely examine the plate choke. I'm looking at a photo that shows it's
*very* tightly wound on a ceramic of Delrin form with fine magnet wire. If
a few turns become shorted due to heating, it could present a self-resonance
condition on 15m.
Also, continue to carefully check around the shorting band-switch for any
signs of heat-arcing in 15m position. The abridged schematic I have shows
two fixed doorknob padding caps, but they're likely inserted for 160m/80m.
It looks like the input matching network is relay switched -- at least the
very early version of the HF2500 offered ca. 1990-1991. Have a close look
at the input relays if your version uses relay switching.
Paul, W9AC
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