Sander deWaal wrote:

Pooh Bear said:

So don't anyone start about bad quality Russkies :-)

I've seen some Zaerix 6L6GCs go zero emission. Took some believing for all
4 to have gone but they sure did. That's more than 20 yrs ago though.

Zaerix was just a brand name, they got their valves from everywhere.
Could have been the USSR at the time you mention, but not likely IMO.
Most of their stock was RFT (DDR) at that time, and they were actually
good valves.

Interesting.

Zaerix was the brand name of Z&I Aero Services Uk - over here at least. Most
of their components seemed to be of CCCP origin. Their power resistors even had
russian characters on them. Plate ceramics did too IIRC.

If you can read German,

A little.

a very interesting piece on valve history can
be found he
http://www.jogis-roehrenbude.de/
Click on "Rohren Geschichtiches".

BTW: how long did it take for those to go "zero emission"?

I don't know for sure - but not long as in *years* IIRC.

To look at, the valves appeared fine and pretty new.

I've never seen this happen with power valves, actually. They might
get weak after many years, but *zero* ? Cathode blasted away?
Rectifiers, yes, like Carys with 1200 uF at the cathode of a GZ37!

I really don't know what caused them to fail. They *looked* fine. Just didn't
conduct any current ! Heaters glowed nicely ! Most odd.

Graham