"Jack Schmidling" wrote in message
...
A friend gave me two 807's for my exciter project. The
first one I tried turned into an 866 and just glowed blue
and had a mini lightning show inside.

The second one looks like it has a coating of soot on the
inside or at least a smoky glass sort of look. It is so
neat and evenly distributed that it is possible that it
was made that way on purpose. I have never seen another
tube that looked like that and no one I have asked has
either.

So, the question is: could this be intentional or is it
indicative of a tube problem?

I can only seem to get about 10 watts out with about 30
input and wonder if there could be some connection.

I just ordered a NOS from Antique Radio but thought I
would ask anyway.


Pics of this project are at
http://schmidling.com/radio.com

The first tube is obviously seriously gassy. Black
coating were applied to some tubes but I don't remember
seeing it on 807's, just some receiver tubes. It might also
be a deposit of something from the filiment/heater. Do you
have a tube tester? Many will test 807's. Low power output
may be due to low filiment emmission the tester will tell
you.


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Richard Knoppow
Los Angeles, CA, USA