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Original Message

About 6J52p

Posted by akltam on January 12, 2017 at 01:10:31:
I bought a bunch of 6j52p and hoping it can replace applications which use D3a.
To cut the story short. Some of the 6j52p tubes only have pin 3 as cathode. Even though the specs say pin 1 and pin 3 are cathode. So those applications that connect to pin 1 ONLY and expect that to be the cathode. You are out of luck. And obviously those application will not work with some 6j52p.
i.e. you need to make sure in your application, the cathode must be connect as Pin 3.
How do I find that out ? I was trying to match those tubes using a signal generator in a self make application which connect to pin 3 as cathode. Everything works fine and readings on every tube looks fine. later I install the tube into my pre-amp which the cathode is connected only to pin 1, some tubes work but some don't. I put back those problemtic tubes to my testing application and it works fine. During the fault finding process, those that don't work do not have their pin 1 and pin 3 connected. These tubes with pin 3 only as cathode are still working fine.
I hope this will help those keep thinking their 6J52p is faulty. Making sure your application is setup with PIN 3 is the cathode.
Alan