"Daniel A. Seagraves" wrote:
>
> [vacuum tube failures can be spectacular]
>
> Hrm. In my experience they just went out like bad light bulbs.
> But then again, all I've ever seen was radio tubes.
Russian quality control still isn't what it might be; I've had maybe
10% of the 6C33Bs I've used internally short within 3 or 4 hours
of initial use. Yeah, I was running them near their limits (in a OTL
design) but I *was* still within those limits. It's pretty spectacular
when they arc over, even with the relatively low voltages used in
an OTL design :-)
A buddy brought me his amp last week complaining that it started to
sound awful a few hours after he rebiased it to "hot up the sound".
Found a nifty hole burned clear through the plate on one of his
EL34s :-)
> I DID get to see a modern radio-transmitting tube about 3 weeks ago. It was the size of a lunch box.
> It wasn't a final tube though - I was told the AM final
> tubes are about the size of my head. It had a metal jacket so you couldn't
> see inside it, but it weighed a hefty amount. It went to some unknown FM
> broadcast transmitter.
They tend to be ceramic or metal/ceramic shells and are designed to be
remanufactured. Most of the smaller ones are designed to be cooled
with forced air, although I believe they still make some which use
liquid cooling. Eimac (www.eimac.com) make such stuff; the photo archives can
be both amazing and frightening...
Cheers,
Chris
--
Chris Kennedy
chris_at_mainecoon.com
http://www.mainecoon.com
PGP fingerprint: 4E99 10B6 7253 B048 6685 6CBC 55E1 20A3 108D AB97
Received on Sat Nov 27 1999 - 10:58:54 GMT