Smokey 807

[K9ACT]

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 smokey 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.

Thanks,

js

[W9GT]

As I understand it, an 807 is just a re-packaged heavy duty 6L6 wth the plate connection on the top.  A lot of glass 6L6s have that "smoked" appearance with the coating on the inside of the glass, but I don't recall seeing an 807 that looked like that.  Anyway, using a known new good tube should answer the question for you, Jack.  It does seem that your output is down considerably from what you should expect with an 807.  You should be able to get 30-40 watts out of one without any strain at all.  Of course, that would require more input power.  But with 30 watts input, you should see 20 Watts or more out.  How much plate voltage are you running?  Low plate voltage might result in lower efficiency.

73,  Jack, W9GT