[Collins] Help with my 30L-1

[Dr. Gerald N. Johnson, electrical engineer]

Parasitic oscillations should be controlled by the four individual
parasitic suppressors in the plate leads of the tubes. Those RL
networks. If they have been burned up by running 872 or removed to
"improve" 10m output that could be the cause of the oscillation.

I recall complaints that some brands or country of origin 811A have a
greater tendency to oscillate. I think that was applied to Chinese
tubes. Tubes with extra long grid leads (and the 811A design dates from
an era when 30 MHz was called ultra high frequency) won't be stable.

73, Jerry, K0CQ, Technical Advisor to the CRA
-- 
Entire content copyright Dr. Gerald N. Johnson, electrical engineer.
Reproduction by permission only.