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Re: VTTC from Eimac 8755 on eBay



Original poster: Jim Lux <jimlux@xxxxxxxxxxxxx>

At 04:52 PM 2/3/2007, Tesla list wrote:
Original poster: westland <westland@xxxxxx>

It's interesting how they use it as an electron gun ... they break off the top part of the ceramic, and they pull off the anode ... I guess leaving them with a cathode gun and a grid to modulate it.

As the fascinating tome on building your own lab gear ("Building Laboratory Apparatus" by Moore, et al.) says: "Don't build your own electron guns. They're a commodity item, and a lot of time and money has been spent by the mfrs figuring out how to make them."
To that, I will add some observations of how they design and build 
things like TWTs.. designing and *building* a high performance 
electron source is very much an art.  Sure, any competent hardware 
hacker who can run a vacuum pump can go out and heat a hot filament 
up and spew some electrons through an anode to make a beam.  Heck, 
Thomson did that back in the 19th century.  But to get a consistent 
flux, with good life, etc.  is definitely non trivial.
If I knew of a tube that had the right electron optics configuration, 
I'd do exactly the same thing. (hey, is it any different than sawing 
the can off a transistor to make a photo detector)
Jim Lux