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Re: NFB - when it's good, it's good, when it's bad, it's bad

163.157.254.25

Hi,

"The electrons hitting the plate do not just go on unabated, they are bounced off the plate by secondary emission and this is fed back into the tube's own "circuit" which is a very quick NFB loop"

Sounds strange to me.
Aint it rather the impact the plate voltage on triodes have of the transfer function that is feed-back? If it is set to transfer 10mA by the grid but the voltage dont reach the expected 250V (assuming load here) due to only transfering 9.5mA the plate voltage will be higher (voltage drop over load lower) and so the transfer would increase a tad (say 9.7mA) - and vise versa.
That kind of feedback aint present in a pentode or tetrode (coz the transfer is set by screen so actual plate voltage has minuscule influence on transfer).

This "secondary emission" explanation sound strange to me.
Think of a tetrode where under conditions secondary emission makes the transfered current decrease with inctreased plate voltage. Would that imply feedback more than 100%?

mvh /Pär

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