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Friday, November 25, 2016

Thanksgiving Day Power Supply

After Thanksgiving Dinner this year I took the opportunity to make progress on the power supply for my 1939 transmitter.

I completed the  500 VDC and 7.5 VAC sections needed for the amplifier.  PSU Designer II indicated that I needed to allow for almost 2000 volts across each of the diodes in the bridge rectifier. I ended up using two 1000 PIV diodes in series for each leg of the bridge. This is a boat anchor power supply with silicon hidden under the chassis. It needed some glow. I added a type 80 rectifier connected only to 5 VAC so that it would look right. After all, real radios need to glow in the dark.

Eventually I'll add components to power the oscillator/buffer stage including 250 VDC, 150 VDC and 2.5 VAC. In the meantime I can drive the amplifier with either my Utah Jr or Meissner Signal Shifter.