[R-390] OT:DC Power Supply for R-392

[James A. (Andy) Moorer]

----- Original Message ----- >
> I recently bought a fair R-392 (it will be on the ship on somewher in 
> Pacific Ocean yet).
> But I don't have any 28VDC power supply.
> I know it draws around 3 amps at 25 to 30VDC but it's really hard to find 
> a good
> used 28VDC PS in Japan.
>

It does run fine at 24 volts. In fact, the 28-volts is too high for the 
filaments in this receiver. They were designed for 26 volts, not 28. They 
work fine at 24 volts.

On the power connector, there is a separate pin for the filament supply and 
for the plate supply. The plate supply actually works better at around 30 
volts. At 32 volts, it starts sounding distorted. What you might do is to 
put 24 volts into the filament pin, then add a small 6-volt supply to that 
to get the 30-volt plate. The plate circuit only draws a few hundred 
milliamps, so the 6-volt supply doesn't have to be very powerful.

Note that you should avoid switching power supplies - they make so much RFI 
that they will swamp the signals you are trying to receive.

Best of luck!

James A. (Andy) Moorer
www.jamminpower.com