>>>>> I can see an oscillation causing very high
>>>>> dissipation,
>>>>> Push-pull parasitics, yes, push-push parasitics no.
>>>>> To explain: With
>>>> a push-pull parasite, the VHF energy from one tube
>>>> alternately pushes
>>>> energy into the other tube,and vice-versa, so both
>>>> tubes have high
>>>> dissipation until the operator stops transmitting.
>>>> However, since
>>>> there is a load on each half-cycle, there is no wild
>>>> and crazy arcing,
>>>> and grid-I is not excessive. If you want to see a
>>>> push-pull parasitic,
>>>> short out both parasitic suppressors in a SB-220,
>>>> transmit, and with a
>>>> litle bit of luck you will see both anodes turn bright
>>>> red, The
>>>> frequency is c. 50MHz. .
>>>> However, Push-push parasitics tend to run amuck
>>>> because they are not
>>>> loaded.
If that is true I wonder why tubes in push-pull amplifiers
don't blow up, why the output of a PP amp isn't zero, why a
push-pull self excited oscillator is easily possible to
build and why it works quite well, and many other things
like that.
Between the push pull parasitics and the melting of glass in
the area where there is no dielectric stress that only
happened in Chinese tubes that would also melt at the same
spot while only having dc, I'm almost thinking this could
just be a fixation about parasitics.
73 Tom
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