Hello

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Please do not think that I am not interested in your relevant information. I have to integrate them and, often, I redo the experiments not to verify their validity but to adapt them to my environment.

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In a previous theard, I showed how I was able to make the plate of a single tube red under a relatively low voltage with a very positive grid voltage. One of the next steps is to move to high operational voltages (CW and SSB) and again to be able to make the plate red in this new condition.

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The removal of the 50k + 50k +5k bleeder resistors worries me.

1.???? It quickly makes the high voltage disappear

2.??? It regulates the high voltage a little

3.??? It avoids stressing the amplifier with a no-load HT which will be equal to the peak voltage

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Here are the measured data:

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With the bleeder resistors and a zero anode current I note:

·???????? CW: 1500 V DC

·???????? SSB: 2500 V DC

At the secondary of the transformer, depending on the transformation ratio and at no load:

·???????? CW: 230 x 2.95 = 678.5 V (960 V peak)

·???????? SSB: 230 x 4.14 = 952.2 V (1347 V peak)

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The high voltage at no load, without bleeder could be (estimated):

·???????? CW: 1920 V

·???????? SSB: 2694 V DC (we are therefore 200 V above the voltage without bleeder - Is this serious ?

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Concerning the polarization, I am a little in the dark. What you are proposing to me is a little like what I did a long time ago, in AM, with a "clamp" modulation on the screen of a tetrode. The idea was then to send the carrier only when the operator spoke. When he spoke weakly the carrier was not at full power. I did this by rectifying the BF to obtain a continuous voltage which was superimposed on the modulation on the screen. This artifice allowed the tube to be used at high power in the modulation peaks only.

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For these 3-500Z, I am trying to apply this principle. When the operator does not speak, the quiescent current allowing to switch from class B to class AB is not useful.

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·???????? When the BF is weak, is it useful? the distortions in % will be higher but since the output power is low, is it serious.

·???????? When the BF is strong (PEP peak), it seems important to be clearly in class AB. Please confirm.

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Do you have a diagram showing where you place the diodes on the L-7?

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73