How do I design "SCREEN GRID DRIVE"

[multi]

You could just use a real zero bias tube like the 811A/572B, 805.
Driving G2 using 807/Kt88/ PL509 and what ever; just makes a zero bias tube.
811a's are cheap any way. The Chinese 572b is an excellent tube 150watt plate dissipation so you can use lots of current.
Phil

 

[bucanian]

You could just use a real zero bias tube like the 811A/572B, 805.
Driving G2 using 807/Kt88/ PL509 and what ever; just makes a zero bias tube.
811a's are cheap any way. The Chinese 572b is an excellent tube 150watt plate dissipation so you can use lots of current.
Phil

Thank you, do you have a schematic of your suggention???

 

[multi]

811a amp

Circuit for 100 watt 811a amp. The original was a record cutting amp.
600 volts is the maximum for the 811A with 70Ma current draw the 572-160 could handle a lot more but the driver circuit would need some changes. I found the Chinese 572b is very good, the Russian 572B's are less stable and cost $170 each. I made two mono-blocks for a Friend he has used the Russian 811A's for 17 years. The Russian 811A or the RCA 811A are the best tubes to use.
I have several more circuits will scan. The 12BH7/6GU7 is the best tube for the voltage amp, not the 12AU7.
The original used mercury vapor rectifiers with choke input; I have used solid state rectifiers with and without choke input.
The Mac used 8005's but can be changed to 811A's. very complicated circuit.
Se 811A.
Phil

 

[bucanian]

Circuit for 100 watt 811a amp. The original was a record cutting amp.
600 volts is the maximum for the 811A with 70Ma current draw the 572-160 could handle a lot more but the driver circuit would need some changes. I found the Chinese 572b is very good, the Russian 572B's are less stable and cost $170 each. I made two mono-blocks for a Friend he has used the Russian 811A's for 17 years. The Russian 811A or the RCA 811A are the best tubes to use.
I have several more circuits will scan. The 12BH7/6GU7 is the best tube for the voltage amp, not the 12AU7.
The original used mercury vapor rectifiers with choke input; I have used solid state rectifiers with and without choke input.
The Mac used 8005's but can be changed to 811A's. very complicated circuit.
Se 811A.
Phil

Hi Phil, thank you very much.

I'm wanting to set a good tube amp to be used in cars, I can design the switching to reverse voltages of 12Vdc to sources as needed. Do you have any suggestions?

Grateful Buck.

 

[multi]

zero Bias amps

Gotham record cutting amp & Mac M1200 from VACCUUM TUBE VALLEY Magazine.
Phil

 

[bucanian]

Gotham record cutting amp & Mac M1200 from VACCUUM TUBE VALLEY Magazine.
Phil

Excellent. Did you ever mointar some of these amps? Thanks. Bucanian.

 

[wa2ise]

Question, is screen drive related to ultralinear operation? In ultralinear operation, the screen is connected to a tap on the output transformer primary, so the screen sees a portion of the signal that's on the plate. As a feedback signal? If true, one could disconnect the screen from that tap, and connect it to another transformer (other end of the winding connected to a B+ source). And this new transformer being driven by a driver being fed the music signal, and ground the g1 of the output tube. Does this make sense?

 

[TonyTecson]

Question, is screen drive related to ultralinear operation? In ultralinear operation, the screen is connected to a tap on the output transformer primary, so the screen sees a portion of the signal that's on the plate. As a feedback signal? If true, one could disconnect the screen from that tap, and connect it to another transformer (other end of the winding connected to a B+ source). And this new transformer being driven by a driver being fed the music signal, and ground the g1 of the output tube. Does this make sense?

no, screen grid drive converts the beam tetrode into a triode....
the control grid G1 is tied to the cathode, and input is fed to the G2...
there are a lot of threads here that you may want to search for...