Thank you for your patience

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As for the resistors at the terminals of the filter capacitors, I understood that they allowed to distribute the voltage at the terminal of each capacitor fairly. It is like for the rectifier diodes with respect to the reverse voltage. This point is understood.

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Indeed the quiescent current of the 3-500Z tubes is probably sufficient without requiring the bleeders. You confirm to me that the no-load voltage (in Rx) will not exceed 2650 V, or 330 V per capacitor.

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Ok for the 50 k? resistor in the grounding of the cathodes. It is the equivalent of what was called automatic polarization and it is indeed stabilizing. It is probably preferable to constitute it by two resistors in parallel in case one cuts out. You suggest that in Tx, the cathode circuit (the CT of the xfmr wire as you say) is made as you indicate to me:

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Note, Drake did not use any bias at all on TX....and idle current was very high ( 210-230 ma). Wire 10 x 1N5408 diodes in series....... in series with the CT of the xfmr wire. The 10 x diodes will provide for 7.2 vdc of bias. This will reduce the idle current down to 100 ma.

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·???????? Do you think that we could use a zener to replace the string of diodes?

·???????? Have you noticed the appearance of linearity distortion by reducing this quiescent current?

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Be aware that in France, our HF power is legally limited to 500 W PEP. The two 3-500Z will therefore generally operate at a slow trot

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F1AMM

Fran?ois