news wrote:
So what happens when a power tubes fades to not good. What if I take a
pair of used power tubes that rate in the questionable area on a tester,
i.e. weak or even bad, and I put them in and turn on.

Do I get a weaker signal? Is the output no longer linear? Cant he
tranny blow up?

What happens when power tubes are used past their useful life?


If the problem is simply loss of emission, it will shift the operating
point of the tube, resulting in increased distortion, clipping of the
signal, and reduced output power.

If the tube is developing gas or leakage with old age, it can also cause
damage to the amplifier circuitry, if the tube "runs away" or arcs over
internally.


73,
Bob Weiss N2IXK