The AM Forum

I want to build a power supply for my GRC-9 and would like to make reasonably compact, so it would fit in a 50 caliber ammo can, I need the following voltages.

Trans. Plates -- 475 - 580 v @  100ma plus or minus 5%

Trans . Filaments -- 6.5 - 6.6 v@ 2 amps

Rec. Plates -- 105 - 120 v @ 45ma

Rec.  Filaments -- 1.35 - 1.5 v @ 500ma

Keying Relay -- 6.0 - 6.9 v @ 575ma

I have a transformer with two windings, 590 volts CT at 130 ma and 6.3 volts at 5 amps.

1.   The 580 volts I would use a bridge rectifier and 200 uf of filter capacitance

2.   The transmitter filaments use the 6.3 volts winding and full wave rectifier, 3000 uf of filter capacitance and a voltage regulator. I would like to use an adjustable regulator in a TO-3 to keep the parts count down. Suggestions for a regulator?

3.   I also need a regulator for the 1.4 volts receive filaments, will use the rectified 6.3 volts winding but need a regulator and would like to use an adjustable regulator, again suggestions for the regulator?

4.   Keying relay, use rectified 6.3 winding

5.   Receive Plate voltage, 105 to 120 vdc at 45ma. I have a 6.3 volt at 1.5 amp transformer, I will connect the 6.3 volt winding to the 6.3 volt winding of the 590/6.3 volt transformer and full wave rectify using 50 uf of capacitance.
My values of capacitance are based on for 1% regulation a 1000 uf per amp for current.

Appreciate any suggestions, thanks !!

 

Probably going to be a problem with regulation of the HV supply on standby with no choke in the supply.  You'll have problems with the receive filament voltage.  What type tubes are in the receiver?? Are they the usual lineup of 1 volt filament type??  I would use two xfmrs, one for the xmitter and one for the receiver if you have something.

I see #5 that you have a second filament xfmr. Better if you have two small filament xfmrs.  Use one backwards like you described and the other one with a
FWB or if it has a CT use a FW rectifier to get about 3 volts and then a resistor and zener or even a resistor and some diodes to ground to bring the voltage down to 1.4 volts.  You'll end up with a rec filament supply with better regulation.

Fred

This will be a challenge. Hum issues are the typical problem. I went through a similar build with my no 19 set. BTW Ammo can will be fine. No choke is fine.In fact eventaully you will wind up there anyway. Bridge might be better on the heater rectifier. Bypass everything insight with .01s. Before you build take a long hard look at the ARC 5 group recommendations. Dave Stinson I believe it is offers some very good although unconventional advice. After many false starts I wound up very close to his recommendations and am pleased with how it is working. I should have followed them up front. My voltages are similar  although not exact. (510 hv, 275v rx and lower voltage Tx and 12 volts heaters (AND Relay and meter LT) There are lots of circuits around and lots of recommendations however these old Mil rigs present their own special problems. The final product that works is a far cry from where I started. I would sugest again you read Dave Stinson ARC5 recommendations and give it a long hard think with mods for your special voltages of course. It isnt going to be easy but it is possible.
donVe3LYX

I am doing the same thing.

I got some of those dirt cheap little buck regulator boards on eBay from China, the ones with the trimpot to adjust the output, and am thinking about using DC with one of them for the low voltage filaments.  I haven't checked yet to see what sort of noise they output, as they typically run at 70 kHz, or whether it will be much of a job to bypass and clean that line so that it can run "battery" tubes.