I read the Deketh book pages 396 to 399 and only found issue with the load imposed on the driver stage for current Fdbk. What paragraph are you referring to?
UnSet fixes the loading with the Mosfet follower.
The problem I see with the usual resistive Schade scheme is that the N Fdbk current is being corrupted by the output tube grid drive voltage swing. The voltage across the feedback resistor is being varied by BOTH the plate voltage swing AND the grid drive voltage (with an INVERSION between them that causes 2nd harmonic distortion for each tube, 3rd H overall ). So the N Fdbk current is no longer purely proportional to the plate V. UnSet fixes that by isolating the tube drive from the N Fdbk. High gm output tubes could minimize the grid V effect, but they only came along late in the game.
Taking the "localized" N Fdbk back to the driver stage cathode or grids (crossed) fixes the corruption problem (more gain in loop minimizes drive V effect on Fdbk ), and that is what is seen in the classic commercial Amps using a localized loop (along with a global loop besides ).
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Used by Philco in their 38-116 receiver, 1938.
Circuit lifted from Beitmans 1926-1938 Most Often Needed Radio Diagrams.
The only circuit of this kind in a reference of 235.
Attachments
so it is not Schade as described in the original circuit
the page you mentioned
this is the first commercial use of the original Schade config I see
Exactly 87 years ago, then nothing similar
Walter
This cct was devised by those left standing shortly after
the Winslow, AZ crater was formed by a
large mass traveling at high velocity.🙂🙂
Oh man, were they lucky, I had to crawl out of that crater. There is something -wrong- with the Universe's chirality near there, L->R
R->L
Cosmologists are saying now that the Universe is spinning slowly, that we must be inside a spinning black hole. Determines fundamental constants like left handed neutrinos, the way clocks turn, how phonograph records spin....