Yes, the 3B28's and a resonant choke filter makes things complicated.? The HV power supplies as far back as the '66 Handbook use silicon diodes in a voltage doubler, capacitor input filter, with a much lower voltage plate transformer secondary (and cheaper).? But I wanted real "old school" before solid state.? Exception - my bias and screen supplies will use silicon diode rectifiers, but they will also have VR and other tubes.
I thought about neutralizing the PA tubes, but most of the stuff I read says it is not necessary with a passive input circuit.? And yes, the passive input negates the low driving power needed by grid driven amps.? Ohms Law indicates I will need a peak driving power of 90 watts into a 450 ohms grid input in Class C, plate modulated use.? I will use 4 x 1800 ohm, 100 watt non-inductive resistors in parallel and a 1:9 ferrite transformer input.? ?Again, more complicated than G-G.
Thanks for commenting.
On Wednesday, April 9, 2025 at 01:31:58 AM EDT, Fran?ois via groups.io <18471@...> wrote:
Hello. I'm 76 years old. I are in my L7 !
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I will use a bridge rectifier circuit with 4 x 866A/3B28 tubes.
I think you're making things a lot more complicated on this point, even though it's nice to see this type of tube working.
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3 new Penta Labs 4-400C tubes in a parallel
Are you considering neutrodynizing the PA? This is where it gets more complicated compared to a ground grid. The big advantage is the gain, but you'll lose it in the aperiodic input circuit.
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73
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F1AMM
Fran?ois
De la part de Lawrence A Lobdell Jr KF7EYF 贰苍惫辞测é?: mardi 8 avril 2025 23:40
