I'm attempting to determine if eight 6J5 gt/g and four 6V6G tubes are good or bad using my Precision 912 tube tester. The tester indicates that all the 6j5 and 6v6 tubes are bad with readings down around 27-35. The problem I'm having with that indication is that exactly half of these tubes are (new/used). Other tubes, such as 6K7G, 5Y4G, and 6L7G test perfectly good with the tester. The radio in question that uses these tubes is not functioning correctly.
My Question is this: How reliable are emission type testers? If the tester indicates that a tube is good, then can I assume that most probably the tube is good, and if the tube is indicated as being bad, then the tube may, or may not be bad?
Thanks,
Romany
More likely a tube tester problem. Even when reading correctly, testers don't guarantee tubes operate properly. Most tubes, even though they test weak, will operate in a radio.
Capacitors are usually the problem if you have hum or distortion. Electrolytic filter caps dry out over time and allow hum. They are inexpensive to replace.
Norm
:Hello,
:
:I'm attempting to determine if eight 6J5 gt/g and four 6V6G tubes are good or bad using my Precision 912 tube tester. The tester indicates that all the 6j5 and 6v6 tubes are bad with readings down around 27-35. The problem I'm having with that indication is that exactly half of these tubes are (new/used). Other tubes, such as 6K7G, 5Y4G, and 6L7G test perfectly good with the tester. The radio in question that uses these tubes is not functioning correctly.
:
:My Question is this: How reliable are emission type testers? If the tester indicates that a tube is good, then can I assume that most probably the tube is good, and if the tube is indicated as being bad, then the tube may, or may not be bad?
:
:Thanks,
:
:Romany
Emission type testers are okay for tube testing but not precise enough to give a good description of overall tube quality.
Usually when there is a critical question of the overall tube quality, because of how the test is accomplished there are some conditions which might pass a tube that would fail a test, or not register as good on a mutual conductance tester.
I have a few testers that you have to give some handicapping factors to because the resistance that gets switched into the test circuit for certain tubes.
When the number of tubes you indicate were tested, and they all tested low- Open up the tester, and check all of the resistors and caps in the tester. Chances are very good that one resistor has shifted in value to 4 or 5 times what the original value was. Normally I have no qualm about buying the untested tubes at radio swaps when they are types like the 6C5, 6J5, 6K7, and a few other types because those usually would test very good. Most of them, especialy military types were made in a robust manner, and in great quantity, that they last a lot longer than a large number of other tubes.
In other words, the tubes you tested are actually good tubes to use for determining if there is a problem with a tube tester.
:Hi Romany
:
: More likely a tube tester problem. Even when reading correctly, testers don't guarantee tubes operate properly. Most tubes, even though they test weak, will operate in a radio.
:
: Capacitors are usually the problem if you have hum or distortion. Electrolytic filter caps dry out over time and allow hum. They are inexpensive to replace.
:
:Norm
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:
::Hello,
::
::I'm attempting to determine if eight 6J5 gt/g and four 6V6G tubes are good or bad using my Precision 912 tube tester. The tester indicates that all the 6j5 and 6v6 tubes are bad with readings down around 27-35. The problem I'm having with that indication is that exactly half of these tubes are (new/used). Other tubes, such as 6K7G, 5Y4G, and 6L7G test perfectly good with the tester. The radio in question that uses these tubes is not functioning correctly.
::
::My Question is this: How reliable are emission type testers? If the tester indicates that a tube is good, then can I assume that most probably the tube is good, and if the tube is indicated as being bad, then the tube may, or may not be bad?
::
::Thanks,
::
::Romany