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RCA Model R78
3/29/2008 10:00:28 AMJohn D
The 82 rectifier tests real weak in this old console. Would a #45 tube work? Don't have an 82.
3/29/2008 11:11:56 AMDoug Criner
John: No. An 82 is a mercury vapor rectifier. A 45 is a triode audio amplifier. Totally different.

Most tube testers do a poor job of checking rectifiers. Is your radio getting normal B+ plate voltage? If so, then the rectifier is doing its job - leave it be.
Doug


:The 82 rectifier tests real weak in this old console. Would a #45 tube work? Don't have an 82.

3/29/2008 6:11:08 PMJohn
Ya, that's wierd! I have this real old sub book by H. A. Middleton that says a 45 will sub and also a 2A3 will sub.


:John: No. An 82 is a mercury vapor rectifier. A 45 is a triode audio amplifier. Totally different.
:
:Most tube testers do a poor job of checking rectifiers. Is your radio getting normal B+ plate voltage? If so, then the rectifier is doing its job - leave it be.
:Doug
:
:
::The 82 rectifier tests real weak in this old console. Would a #45 tube work? Don't have an 82.

3/29/2008 8:34:24 PMDoug Criner
Hmmm. I think that substitution book must be in error. If you compare the pinouts for those tubes, you will see that they are different.

2A3s and 45s do have the same pinouts, but have different filament current draw and different specified plate voltages. I don't think they are interchangeable. The 82 is a full-wave rectifier, a completely different thing, electrically - the only thing it has in common with a 45 or a 2A3 is that it fits in the same type socket.

But anyway, if the radio works, the rectifier is OK. Or, even if the radio doesn't work, but you're getting satisfactory B+, then the rectifier is OK.
Doug

:Ya, that's wierd! I have this real old sub book by H. A. Middleton that says a 45 will sub and also a 2A3 will sub.
:
:
::John: No. An 82 is a mercury vapor rectifier. A 45 is a triode audio amplifier. Totally different.
::
::Most tube testers do a poor job of checking rectifiers. Is your radio getting normal B+ plate voltage? If so, then the rectifier is doing its job - leave it be.
::Doug
::
::
:::The 82 rectifier tests real weak in this old console. Would a #45 tube work? Don't have an 82.



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