John, you get to play with some of the *neatest* stuff!
My Dad has some books on vacuum tube design and characteristics. One is by
Spangenberg and he has two others (can't recall the author). I was reading in
Spangenberg about TT filaments vs oxide cathodes. I didn't see anything about
power cycling, but there was quite a bit in there about optimal operating
temperatures and the ways that oxide cathodes get poisoned. Pretty interesting
stuff. There was also lots of stuff in there about odd-ball (to me) very
specialized tubes for all sorts of pulse generation and high-speed switching.
I needto ask my Dad if he's willing to let me have those for my library :)
Cheers,
Kim N5OP
----- Original Message ----
From: John T. M. Lyles <jtml@lanl.gov>
To: amps@contesting.com
Sent: Wednesday, February 14, 2007 1:18:38 PM
Subject: [Amps] Incandescent and tube filaments tspa
One thing to consider when comparing these, is that the filament in a
lamp is lit to incandescence, higher temperature, than the filament
in a TT or oxide cathode filament. These are typically less than
2000K, dull orange or less for oxide cathode. Also, the light bulb
filament, does it use thoria in it or is it pure tungsten? Way
different mechancially. Finally, the light bulb filament, in my
recollection, is coiled like a tiny spring, or so i thought. Tube
filaments are bars, strands, sometimes coils, but much different
geometry. In some tubes they are tensioned with a mechanism to allow
for changing dimensions when they warm up.
John
K5PRO
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|