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BC-348 Power Supply
11-29-2023, 03:02 PM
I've acquired a BC-348 receiver and need to make a power supply. There are several designs out there, with the Hallicrafters conversion being the most widely known. But my research has turned up that Philco also had designed or made a BC-348 power supply for 117 V house current. Does anybody know anythng aout it of have the plans? Thank you.
11-29-2023, 06:25 PM
IMHO Any supply made to fit in quantity would have been via gov. contract, in doing so, they would all be alike.
Pliny the younger “nihil novum nihil varium nihil quod non semel spectasse sufficiat”
11-29-2023, 07:48 PM
No, none of these were gov't issue. This was after the war, when they were being bought by hams and Hallicrafters offered an AC power supply to replace the original dynamotor. But I have read that Philco also offered one, but cannot find any info about them. It would not necessarily be the same design. There was no government issue or mandate on these radios, now in private ownership.
11-29-2023, 08:45 PM
I've had one or two (BC-348's) over the yrs but it's been a long time ago. Here's a good starting point https://www.radioblvd.com/bc-348_dynamotor_part3.htm I don't remember if you have to rewire the heater circuit to make it usable at 6.3v vs it's normal 24vdc. That's a common thing with WWII aircraft set like the command set SCR-274N/ARC-5 that were dynamotor powered.
If you can find a pt that can make 250vdc at 60 or 70ma + a 24v transformer to power the heaters that's a good start. The rest is just some caps, diodes, and resistors. If you have some room a choke is always a good think to filter the hum out. When my pals were reading comic books I was down in the basement in my dad's workshop. Perusing his Sam's Photofoacts Vol 1-50 admiring the old set and trying to figure out what all those squiggly meant. Circa 1966 Now I think I've got! Terry
11-29-2023, 10:16 PM
Quote:No, none of these were gov't issue. This was after the war, when they were being bought by hams and Hallicrafters offered an AC power supply to replace the original dynamotor. But I have read that Philco also offered one, but cannot find any info about them. It would not necessarily be the same design. There was no government issue or mandate on these radios, now in private ownership.At a local estate sale (1985) of former Air Force pilot I bought a 348, it is equipped with a gov power supply drop-in for dynamotor. Some 348's never flew and were used on ground in a military environment thus the gov supply. Pliny the younger “nihil novum nihil varium nihil quod non semel spectasse sufficiat”
11-29-2023, 10:27 PM
Well if the government issued them I'd like to see that design too.
11-30-2023, 10:24 AM
Here's what was done right after the war. You may find some of these circuits added to your set. In those days 120 to 24v transformers were rare now a dime a doz. I would bother to rewire the heaters just use a 24v trans.
https://www.w7ekb.com/glowbugs/Military/...l_vol1.pdf See pg 29 When my pals were reading comic books I was down in the basement in my dad's workshop. Perusing his Sam's Photofoacts Vol 1-50 admiring the old set and trying to figure out what all those squiggly meant. Circa 1966 Now I think I've got! Terry
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