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In Reply to: RE: Need some opinions and maybe a lot of help with 300B design. posted by Paul Joppa on March 14, 2016 at 13:44:58
Hi Paul. I guess I'm not getting it. I was aiming for 350 on the Plate, -74 on the grid which with a 5000 ohm load should give me around 6.5 watts or so. Am I looking at this wrong? I can increase the cathode voltage to -76 easily enough. That should give me at least 6 watts right? Thank you for taking the time to look at it by the way.Gavin
Edits: 03/14/16 03/14/16Follow Ups:
The schematic you posted indicates cathode bias. That means the anode-cathode differential will be less than what the PS provides relative to ground.
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Buy Chinese. Bury freedom.
Exactly right!
T_K knows this but for others who might read this post and scratch their heads I'll note that it's a classic mistake, probably everyone here has fallen for it at some point: There is no such thing as "plate voltage"; there are only voltage differences, e.g. plate to cathode in the table and on data sheets, plate to ground, etc.
Here is my attempt at a power supply for the above. Yes I know the 5AR4 is not drawn correctly but the liitle sketch-it web app @ Digikey is kinda limited. Best I could do.Gavin
Edits: 03/14/16
This should give you much more than 375 volts, closer to 500 volts. With that, you can run around 60mA (using a 1500 ohm cathode resistor) and drive 8+ watts through the Robin Hood 5K output transformer.
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