[Amps] LF oscillation caused by defective plate choke?

[peter chadwick]

>###   250 uh is fine for the plate choke.     Instead of the 1000 pf bypass cap,  use 2-3 x 4700 pf disc ceramics.     That combo makes for an excellent lower freq bypass cap.  
Then wire 1-3 x  500pf ceramic doorknob caps in parallel with the 4700 pf caps.   The 500 pf caps make for an excellent higher freq bypass cap.<  


You will have about 1 volt across that combination on 80m. Using 1 4700 pF cap and 1 500 pF cap in parallel will give 3 volts: then a 50 microhenry choke and another 4700 pf will drop this to 27mV and you have saved 1 or 2 500 pF caps and 1 4700 pF cap and got a better result. Just adding capacitors gets to a state of diminishing returns.

73

Peter G3RZP