> I'm more curious as to what your attempted power
> parameters are. If they
> aren't high enough plate load you will never be able to
> find enough
> capacitance to resonate that thing. I doubt you are
> running 3 -8877's with
> 2500V on the plates. They made them to run a 3-1000 zero
> bias with 2500V
> and who runs just 2500V? A 3-1000 isnt happy until it has
> at least 3500V on
> it. Even at 3000V that thing is already long for the junk
The nice thing about tank circuits is you can be off by a
factor of even three or more and it will barely make a
difference in amplifier output.
All the worry about getting the Q right at 12 or some other
magical number is largely a waste of time except the minimum
Q results in less circulating current. All you really need
to do is add enough C to make it hit.
Look for example what Dentron did in the MLA and
"Clippertron". They had some fixation that a pair of 200 pF
across a few hundred pF variable was about right. Switch
them out on 80, and the C instead of being half the 160
value is now nearly 1/4th the 160 value. The Q changes by a
factor of nearly three or four, yet the efficiency remains
almost the same. The amp doesn't suddenly "quit working"
because the Q is not some magical number.
As a matter of fact many VHF and UHF tube amps work happily
with a loaded Q of 50 or 100, sometimes even more.
Throw in a little more C and with the meaty coils in the B&W
the thing will work just fine.
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