Yeah, I always thought an "open circuit" was something that needed to be located and repaired.
That's generally the case, yes.
But maybe that's something else entirely...
Well, in TheChairGuy's post, "open circuit" seems to relate to the vacuum within which the tube's electrodes exist. And yeah, if you have two terminals separated by a vacuum, air or some other insulator, you would have what amounts to an open circuit as there would be an exceedingly high impedance between those two terminals.
But if vacuum tubes were an open circuit as implied here, they simply wouldn't work because you wouldn't be able to get current to flow from the tube's cathode to its plate. So this whole notion that tubes are an "open circuit" because of the vacuum inside of them is a load of rubbish.
Plus, vacuum tubes are also known as valves, and I never heard of a valve that didn't open and close.
Ha! Quite so.
And ultimately, transistors are no less "valves" than tubes. Each are three terminal devices (in the case of the triode anyway) which use one terminal to control the flow of electrons between two other terminals. Both can be turned off, and in class B amplifiers where each half alternately handles half the signal while the other half is off, this is the case whether you're using tubes or transistors. Similarly, in class A amplifiers where the devices are always on and never turn off, this is also the case whether you're using tubes or transistors.
So I can't for the life of me figure out how someone could say what TheChairGuy claims someone said without their being utterly clueless about how tubes and transistors function.
However I'm the last person to get involved in a technical discussion.
Hey, you're applying some thought and reasoning so no reason you shouldn't get involved.
se