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previous: Pat F Picked up an old PA with 7868 OP tu... -- 8/3/1999 9:50 PM

Re: 7868 compatible tubes

8/3/1999 10:52 PM
Dirk	Re: 7868 compatible tubes RCA Receiving Tube Manual shows Push-Pull Class AB1 at Plate/Screen Voltages ranging from 300/300 to 450/400 as 6600 ohms effective plate-to-plate load resistance when using fixed bias. Cathode biased (70 ohm) at 450/400 it lists 10,000 plate load. Guitar amps seem to run loads of 70-75% of what the manual lists. I suggest measuring the turns ratio and calculating the impedance of the OT raher than guessing.

8/3/1999 10:52 PM

Dirk

Re: 7868 compatible tubes

RCA Receiving Tube Manual shows Push-Pull Class AB1 at Plate/Screen Voltages ranging from 300/300 to 450/400 as 6600 ohms effective plate-to-plate load resistance when using fixed bias. Cathode biased (70 ohm) at 450/400 it lists 10,000 plate load.

Guitar amps seem to run loads of 70-75% of what the manual lists.

I suggest measuring the turns ratio and calculating the impedance of the OT raher than guessing.