[R-390] Ballast Tubes

[ToddRoberts2001 at aol.com]

I think this has been said in the past. It is a bit more work in the 
beginning but I have had very good results by re-wiring the filament line in the I.F. 
deck to run the BFO and PTO tubes in parallel with the 6.3VAC filament line. 
This does away with using a resistor and saves the heat being dissipated. If 
you want to keep the original look of the radio just plug in a dead 3TF7 in the 
socket and leave it there. No one will know the difference unless they touch 
the tube and find it is cold. All I know is one time I used a variac and varied 
the 115 VAC line voltage +/- 10 volts with and without the ballast tube - 
with the BFO turned on - I couldn't hear any change in the beat note with the 
receiver tuned to an AM BC station. 73 Todd Roberts WD4NGG.