| Let me say this about "But we all know any tube less than 100% is showing signs of age and possible performance." I didn't know that. What's your tester? Some tubes are oranges and some are apples and whatever else. Some tubes will never read 100% even brand new ones. Your tubes reading 65% may be excellent performers. Tubes reading barely in the green or even in question area could still do ok. If I was testing a tube from a set say a 6EU7 and thought it was reading low I would test another good one and compare them. Testing a number of the same tube, same manufacturer, and known to be good generally results in very close reading for all on the green scale. I like a tester which checks leakage too. The tubes in bad area are to be replaced. You could always sub back in set if not shorted to see the difference. And remember the best test for an oscillator in my opinion is the set. Somtimes you got to swap them out regardless of tester results. For me anything in the green stays in the set for a trial. For me I think the most replaced tube reading in the green after this trial period is the output tube. Bill VA
:I am replacing Tubes on a 1960 RCA stereo, the unit has a total of 14 tubes for the power supply and amplifier. As I test the individual tubes with a tube tester, I am finding the variations one would expect after 45+ years.
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:I have tubes that have tested "GOOD" at 65% and others at 85%. Also, only 2 that tested "BAD" at 25%-35%
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:So, one would simply conclude that any test results showing in the tester Green Scale as "GOOD" is acceptable. But we all know any tube less than 100% is showing signs of age and possible performance.
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:I/m looking for feedback from the experts, what level should be the lower threshold of acceptability. Should tubes below 65% be replaced and those above installed ?
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:I want to have some level of confidence after replacing all the capicators and bad/questionable Tubes this unit should work correctly as expected.
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:So, what is "GOOD" enough ?
:Comments ? |
Bill 
Doug Criner 