[HomeBrew] DIY Vacuum Tubes!

[James Kearman]

DavidE Benedict wrote:
> DIY Vacuum Tubes!

When I was a kid and didn't know it couldn't be done, I made what I 
believe was a working "vacuum" tube diode. I used a Mason jar, in which 
I rigged a circular anode around a nichrome-wire heater/cathode. I 
sealed the holes in the cap with wax, and put a couple of birthday 
candles inside to burn up the oxygen. Lit the candles and threaded on 
the jar.

I know the candles did remove quite a bit of the oxygen. I could make 
the heater very bright after they'd burned out, and when I unthreaded 
the jar and let air in, the heater would burn out. I hooked up a 
voltage-doubler supply built from a TV power transformer, so I had about 
1700 V. I only had a Simpson 260, but I could see current flow, that I 
couldn't duplicate by running the heater at its maximum brilliance just 
short of burning out, when the jar was removed.

Of course, I had about 100 lb of tubes in those days, and if I'd been 
smart I would have been making transistors. That had to wait until I 
went to work at IBM's East Fishkill, NY, foundy in 1970. :)

73,

Jim, KR1S
http://kr1s.kearman.com/