#18516
Dan Middleton
CVRS Member

Les, For the radios designed for 25 Hz I always end up adding a resistor between the rectifier and the first filter capacitor. The value is selected by how much you need to reduce the B+. I recently worked on a Stromberg Carlson 180. This unit has 400 volt B+ and an idle current of a whopping 200 ma. It required a 200 ohm 50 watt power resistor to drop off 45 volts. The resistor runs blazing hot. I attached a photo. I built a cage around it for safety. One end has 450 volts DC.
I have an AC powered TRF I’m working on that was putting out 220 volts DC instead of 150 volts. It needed a 2,000 ohm 10 watt resistor. The current draw is only 25 ma. It runs warm.