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Re: [Amps] HF2500 - 15 meter problem

To: "'Steve London'" <>, <>
Subject: Re: [Amps] HF2500 - 15 meter problem
From: "Paul Christensen" <>
Date: Wed, 24 Aug 2022 19:30:57 -0400
List-post: <>

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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