BC-348-O High voltage

[WB4YVO]

All, How much current does the HV draw?   I think about 80 ma?  The voltage I think needs to be between 215-225 Volts..

My Power supply  is reading approx 350 Volts   NO LOAD.. How do I calculate what value resistor to use in series with supply to get to that value?

Skip

[KA3EKH]

So that’s how it is, now you got the bottles lit up you want to see them work too. What are you using to supply the high voltage? Remember that an unloaded power supply will rise up well beyond its regular loaded voltage.
Ohms law again! 225 VDC @ 0.08 Amps = 18 watt load. R = V/I (225/0.08=2812) so if you stick a 2800 Ohm resistor across your power supply that would duplicate the load the radio draws. Just be aware that your going to need like a twenty-watt resistor!

After all this time also have to ask, got pictures?

[KA3EKH]

Well if you’re not going to show me yours I will show you mine! This is the last BC-348 that I did, it was not finished at the time of this picture being it had just gone thru a face transplant. You can see the new internal AC power supply inside. Note that I use a 6X4 instead of solid state devices for a couple good reasons. First the delay in warming up the tube avoids putting HV on the receiver and having it climb stupid high before the tube warm up, second is that the tube drops some voltage so the B+ is further reduced and last but not least somehow, I have tons of NOS 6X4 tubes so this finds a use for them. Also attaching the schematic of the power supply I have in that radio. The transformer is from a URR-35 VHF AM Receiver that was about useless but the transformer is the perfect size for fitting in the receiver. Also, I kept the big capacitor 70A/B being although accent it was still at eight micro farads and had no leakage.

[n8fvj]

350 volts is just too high. Huge voltage during tube warm up. Find another power supply.

[WB4YVO]

I will take a couple of pictures and post them..

Skip