Re: Ferrograph Quiet Crackly Audio
Do not know the actual values when in a Series 5. A shame the manual does not list them.
Heater voltage would expect to be 6.3VAC, this is off a separate transformer winding to the heater supplies for the other valves which is listed as 6.3V
The AC voltage across the anodes will be at least 500 volts and could be as high as 750 volts, depending upon the actual transformer secondary winding output. This winding has a centre tap, so it would be safer to measure each anode to the centre tap, i.e. lower/approx half voltage.
The cathode is the rectified DC output, in the manual it is referenced as 285 volts in Playback mode. i.e. "input to smoothing choke L5".
All voltages are approximate, the rectified DC output can vary somewhat depending upon load and reservoir/smoothing capacitor condition.
Be extremely careful measuring the high voltages.
David
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