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In Reply to: RE: Tube Radio sounds great then fades.... posted by MannyE on May 28, 2016 at 12:15:17
It's something. My experience when it does that it's more often a tube. I restore old radios. However a guess is just that. Do you have a tube tester? What's the make and model of the radio? Have you ever worked on stuff? If you're OK with soldering and have some tools and test equipment tube stuff like that is easier to work on than solid state. Let's here more
ET
Follow Ups:
It is an RCA Victor Model X-551 "Golden Throat" I don't have access to a tester, but the power tube (I assume because it's the big one) has a big silver blob along the side. I don't know if that means anything.The chassis has RC 1089B and U 274 stamped on it.
Edits: 05/30/16
The radio has five tubes in a series filimant, no transformer. You can get all five for under $20 on ebay. The silver color on the tube is no big deal. Also because the sound goes away doesnt mean the audio output tube is the problem.The five tubes are
12BA6
12AV6
12BE6
35W4
50L6Radios with five tube no filimant transformer are called All American fives or AA5. Your radio was designed with four tubes from the second generation of these radios and the 50L6 which was from the first generation.
Take the chassis out or at least take the back off. If when the radio cuts out out all the tubes become dark or turn off one tube filimant is at issue. Could be a cap or even a cold solder joint too.
Next time it cuts off jiggle and tap all the tubes one at a time in their sockets. Better yet remove them all and clean the pins and sockets and reinstall them.
ET
Edits: 05/31/16
When one tube heater connection stops, all downstream stop.Series connection.
Edits: 05/31/16
I will check and report back the findings.
The back comes off quickly with 4 screws but I haven't figured out how to safely remove the antenna. I assume it unplugs somewhere, which I will figure out when I have it on the bench with more time to peer into it.
Actually few of those antennas disconnect you usually have to unsolder the two connection points.
ET
Well that's a pain in the ass isn't it? How was the consumer supposed to replace the tubes? I have to say that it is hands down the best AM receiver in the house. I guess back then the engineers ruled. :)
The back will remove far enough to take the tubes out. However it will hang there and eventually break loose if you are not real careful. Ive resoldered quite a few. You should hear a nice console radio with ten or more tubes. They can be great. A Zenith with two audio tubes in push pull and a twelve inch speaker can really be something.
ET
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