[R-390] Another Conundrum

[David Medley]

In the R-390 regulated power supply is a single 6BH6 tube. This is a pentode used as a DC amplifier. It is becoming expensive and difficult to find sometimes. The other day I found some on ebay NOS Amperex brand. The price was great. They duly arrived and the boxes were in great shape. Looked like new. So I plugged one in to the R-390 I was working on and to my surprise the 180v soared to 300v!! So I assumed that this was just a bad tube so I plugged another one in. Same result. So I looked carefully at the tube. Stamped 6BH6 like on the box but the tube was obviously not a 6BH6. Looked like some kind of dual triode. No resemblance whatsoever to the real thing. Made in Japan.
So guys if you need a 6BH6 for your R-390 look carefully at the tube before you plug it in especially if it is Amperex made in Japan. 300v is very bad for your radio's health.
Dave
 


Sincerely
David Medley
davidmed82@yahoo.com
If you have a minute please check out:
http://www.adminder.com/c.cgi?davidmed&123
You might even make some money!

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