Carl says:
>Then get back to the group for Phase 2 if necessary. Often the first sign
>of aging tubes is power loss on the higher frequencies
Why is the output low on the higher frequencies? I agree with Carl that it
often is a sign, but I fail to understand why. If the peak cathode current
is available on 80m to give full output, why isn't it there on 10? I guess
one could assume that if the gm is going down, the input impedance will
change, but that should be seen on the other bands as well. Might be
interesting to do an input SWR measurement with old tubes, then substitute
new ones and see if there's a difference.
73
Peter G3RZP
--
FAQ on WWW: http://www.contesting.com/ampfaq.html
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|