In article ,
Scott Dorsey wrote:
Hank wrote:
I've always felt that deForest's history was another exercise in
alchemical strangeness. It seems fairly clear that he did not have any
real understanding of why or how his tubes worked, or what they might be
capable of actually doing. Nor did he ever devise any practical
circuitry for using them. A much larger contributor to circuitry was
Armstrong, whose patents were overturned in favor of deForest later
on---generally regarded as a travesty of justice. Development of the
high-vacuum triode with a scientific understanding of what the control
grid was doing to the electron stream---and development of a concomitant
technology for series production of the devices was more an AT&T/Bell
Labs effort. Also, the first major use of these devices was as
telephony repeater amplifiers.

Well, one of the problems is that DeForest was convinced that electron
propagation in the vacuum only took place if there was a small amount of
gas left in the tube. In fact, if you do allow a little gas in there, you
get much higher transconductance but much poorer linearity (the extreme
case being a thyratron where all of the electrons are carried by ionized
gas). Because DeForest never really got the idea of modelling the tube's
transfer function, he was never able to separate out the two mechanisms
and consequently was never able to make consistent devices.
--scott

DeForest's misunderstanding of the principles of the Edison effect and
the Fleming valve seems to have been pretty basic. His first attempts
to control current flow were "grids" mounted on the outside of the glass
envelope. And he always seemed to think that what he was controlling
was ionized gas conduction, not electrons emitted from a cathode
element.

There were tons of texts written around 1920 that had some pretty
strange theories about what tubes did inside. As I recall, the first
really good text on radio circuits I encountered was Mary Texanna
Loomis's text from the late 20's. I learned EE basics from her text,
Ghirardi's "Radio Physics Course" from 1932, and Terman's 1937 "Radio
Engineering." One text that baffled me was Zworykin/Morton
"Television," which I got as a present at the end of WWII. No
wonder--the physics were much too advanced for me to understand.
Looking back some years later, I think the best text on vacuum tube
physics was Spangenberg's "Vacuum Tubes." It wasn't published until the
dawn of the transistor era, so never got the play that Terman and some
of the others did.

Hank