[TMC] PAL 350 questions

[Chris Bolkan]

Hi TMC lovers!

I have been tinkering with my PAL 350 and have a couple of questions.Can
anyone tell me if the power input requirement (100mw I believe) to achieve
full output is based on RMS, peak or P-P?

I have been struggling with neutralizing the finals. I've used the
procedure in the manual but I do not have a HF VTVM so I was using a 100Mz
scope with 10x probe. My results were less than satisfying when going back
and forth between 16 and 32 mHz and trying to get a consistent 1V. So I
tried something else that seemed to work pretty well. I would like feedback
to know if there is a fatal flaw in my approach.

Procedure that seemed to work:

I turned off the HV and grounded it because the "off" state neon light
still allowed enough current to pass through the primary of the power
transformer that it produced 250 or so volts under no load on the finals.

I disconnected (unsoldered)  the feedback coax from the finals to the
driver cage.

With the amp on but HV off (covers on the amp for shielding) I fed a 32 mHz
signal from an RF generator to the amp input and peaked the driver stage
tuning. I then set the generator level for about 1/4-1/3 meter deflection
on the driver output meter and re-checked the tuning peak.

I hooked a 50 ohm load up to the output of the amp with a 100 mHz scope
across the 50 ohm load. I peaked the tune and load controls for resonance
(maximum signal) on the scope.  I re-peaked the drive tuning which really
hadn't changed and double checked the peak voltage on the amp output with
the tune and load controls.

I then screwed the neutralization adjustment on the back panel in and out
and found a defined dip in the signal on the scope. I am hoping that dip is
where the finals are neutralized.  I re-checked the tune and load peak and
it had not changed. When I took the top cover off the gap between the disk
and plate was around 3/8-1/2 inch by eyeball.

Does this sound right?

One other question: How can I tell if my final tubes are good? What do
tubes that are getting old and weak behave like? Tetrode amps are new to me
and there is a lot I don't seem to really understand.

Thanks!

Chris
KI7NXY