[TMC] Friday PAL 350 update

[Chris Bolkan]

Hi TMC lovers!

I reassembled the amplifier after verifying that the screen grid bypass
capacitors are good. Powered it up to make sure everything still works and
it does.

I tuned it up at 3.9 Mhz into a 50 ohm load. Tuned the drive to 3.9 mhz ,
then applied HV. Dipped the plate current with tune and peaked output with
load as drive was increased. Did this until plate current was 240 ma. At
240 mA, power output was 50 watts, Drive level was 20, Screen grid current
read 0.

I could probably roast weenies over the output tubes. It purrs along
nicely........at 50 watts.

Once all tuned up I fiddled with the tune and load controls and saw
virtually no change in screen current. This is suspicious because I would
expect to see more happen here. But it doesn't.

Could my finals be weak? Do these symptoms align with weak finals?
Everything seems to work so well and tunes up so nicely that I wonder if
the tubes are weak. I'm out of other things to try.

I have no way to test these tubes because I do not have a known working amp
to check them with. Unless someone has more ideas of something to look at,
test or do, I am out of ideas except for testing the tubes.

Without a known good amp, is there a way I can test these tubes? If
not.....this is a big ask, but is there someone willing to put my finals in
their known working amp and check their condition?

Until I know the tubes are good (or not) I don't know what else I can
try, or even if trying other things makes sense.

As always Thanks for all the help and advice.

Best regards,

Chris