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[Amps] Cleaning and lubrication of ribbon variable coil

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Subject: [Amps] Cleaning and lubrication of ribbon variable coil
From: "Bill Lee" <>
Date: Tue, 9 Aug 2022 11:06:32 -0500
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I have a 1960's vintage military surplus amplifier that I am attempting to
put on the air. It is a Harris/Gates HFL-1000. It uses a large ribbon wound
variable roller inductor coil in the PA circuit. This inductor is different
from most roller inductors that are wire wound on a ceramic core with the
roller outside of the coil. This roller is on the inside of the coil. I have
attempted to lubricate the roller shaft with the lubricant from Palstar.
With the roller shaft inside the coil, it is difficult to get the lubricant
all along the length of the shaft. In using a CAA-500 MII to check the PA
dips versus the tuning chart, I can tell that the roller is not making good
contact along the entire length of the shaft (where I can't get the
lubricant on the shaft). I have some questions: (1) suggestions as to how to
get lubricant along entire length of shaft, (2) does the roller itself need
to be cleaned as it has some oxidation on it. It appears to be making good
mechanical contact with edge of ribbon. (3) Should I clean the inductor
shaft/end plates sleeves with say IPA and then use Deoxit as a further
cleaner/lubricant? The Deoxit that I have is not the deluted spray, but the
concentrate in the small bottle.


Thanks for suggestions, comments.


Bill Lee WA5LTA

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