• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Baking Tubes Procedure - Help...

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My regular domestic GE goes to 550f. At least once a week to bake me some home made pizza.
Cutting the latch off the lock and putting it in clean mode is another trick of home pizza chefs, and maybe tube bakers as well. Then you can get to about 900f.
Lemme make sure I've got this straight. we're supposed to make our ovens unsafe in order to melt our tubes and we're supposed to do this before we actually put those tubes in an amplifier to see if there's actually anything wrong with them?

Is that right?
 
I can't see a mere 300 - 400 degrees F doing anything at all to rearrange the metals or gas molecules in the tube or create any kind of "healing effect". There is some chemistry in the tube with Cathode coatings. but tubes run from 1200 to 1700 Kelvin at the cathode, thats 1700 to 2600 Fahrenheit! 350 degrees is a winter compared to 2000 degrees. I don't buy this. On the other extreme we have cryogenic sellers, to me cooling a tube in liquid nitrogen wouldn't do anything except maybe break the seal between glass and the pins due to different expansion rates.
 
Baking the tubes isn't going do do anything to get the heaters to light. Maybe bake off some greasy crud from the heater pins.


Very possible this is what helped the tubes start working after heating them in the oven. I can't say what heating tubes in the oven did that helped them start working. Maybe there was moisture or crud inside the base or pins causing problems, anything is possible all I can say for sure is it worked and saved tubes from the trash.
 
And did you try them in your amp before you cooked them?


I did not try them in the amp before. These were supposed to be "nos" but as I mentioned they were stored poorly for the past few decades so I didn't want to destroy anything by plugging in unknown junk. I have a couple of tube testers but no tester is perfect so I usually check with Simpson or Triplett meter for continuity/shorts in addition to the tube tester. Tubes and audio equipment are nothing more than a fun hobby but I have a little bit of experience testing equipment from 20 years of working on low and medium voltage electronic equipment.
 
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