Quote:
Originally Posted by Electronic M
Many early AC powered TRF sets used paper caps for filtering since lytic technology wasn't there yet. Higher uF paper caps get bigger and more expensive as capacitance increases so many TRFs had less than ideal filter capacitance as a result. Increasing filter capacitance is advisable if mild to moderate hum exists post recap or as a preventative measure now.
|
True enough, although when using a choke filter it's possible to get the input capacitor too large and the B+ will go higher than intended. If hum is a problem I'd first try increasing only the cap on the output of the choke.
I'm now having reservations on my recommendation of 250wvdc for the caps. If the 80 rectifier turns on before the other tubes fully conduct, B+ could temporarily become much higher than normal. 350-450wvdc may be the safer bet given how small modern electrolytic are. What are you guy's thoughts?
Ultimately once you get the set operational you can monitor the B+ and see how high it surges at turn on.