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Originally Posted by kalee20
The 'special circumstances,' though, are not mentioned by Sturley! He's an author of pedigree, but it's still appropriate, as good engineers, to challenge and try to understand WHY.
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One of the nice things about writing a book (unlike lecturing, for example) is that you can use vagueness to sweep messy details under the carpet. Sometimes this avoids adding many pages (which might upset the publisher), sometimes the author is just not interested in that topic, and I assume sometimes the author realises that he does not know enough about that topic to write anything useful but still needs to mention it in passing.
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With an infinite impedance detector, AC/DC load is not an issue as long as there is a sufficient cathode current drain to allow the cathode capacitor voltage to decay between HF cycles so that it can always follow downward modulation.
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The capacitance is still being discharged by a resistor, so it still suffers from the negative peak problem. The valve cannot do anything further beyond being cutoff. AC/DC load is less of an issue because the II detector cathode circuit can use lower impedances than a diode detector, but it is not a non-issue.