Robert and all
Re "I am no expert but I believe you can't rely too heavily on any tube tester. "
Well if it "reads bad" it likely is bad.
if it "reads good" it may well be good under the condition it is being tested at.
Most TTs measure Gm [where amplification is part of the intent in the tube.]
If you have a variable Mu tube you really want to know if it works properly with a small bias. But you want it to also work properly at a large negative bias
.. if you don't test it down there you might not know it has too hi a gm .. maybe that is where the gas messes things up like Jacques said.
I recently saw other postings somewhere the front end tube tested ok … but did similar things
.. but we need to get the books out on the details
From: Amateur-repairs@groups.io [mailto:Amateur-repairs@groups.io] On Behalf Of Gary WB6OGD
Sent: Friday, January 19, 2024 11:58 AM
To: Amateur-repairs@groups.io
Subject: Re: [Amateur-repairs] Creating a LSB and USB Test Signal!!
Robert,
Good advice.
I am no expert but I believe you can't rely too heavily on any tube tester. The actual circuit where the tube goes is the best tester.
I downloaded the 51s1 manual just to have a look. The BFO is one tube. I would try another, there are probably many types that could substitute
there if you don't have a good spare. I am thinking it maybe has a filament to cathode short or leakage of some kind that lets the AC filament signal onto
the BFO signal. But just a guess.
73,
Gary
WB6OGD
--
73 don va3drl
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