Perhaps there was or was intended to have a 12 volt option for the BC348?  The BC603 from the SCR 508 family has a 12/24 option. All the tech has to do was install the dynanmotor  for the required voltage and the filaments were rewired internally via the dynamotor assembly  .

On Saturday, July 6, 2024 at 09:40:15 AM EDT, <[email protected]> wrote:


I have been working on a BC-348-N, restoring it to original configuration.  I have a DM-36 24VDC 220VDC dynamotor and an actual BC-348 dynamotor base to power it and have wound the required filter coils.  The most challenging aspect has been rewiring the tube filament strings and installing the missing resistors in those circuits.  I could not figure out why a 28 VDC input did not make it to the filament string.  Then I realized that the 28VDC power runs Through The Dynamotor Pack, a jumper between two terminals.  I have no idea why they did it that way; perhaps it would make substituting an AC power supply easier?

Wayne
WB5WSV     
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