[Amps] New 4-1000 Tubes ?

Carl km1h at jeremy.mv.com
Sun Jan 6 20:15:02 EST 2013

Hello Carl,

You wrote 5 января 2013 г., 22:30:46:

> It only has a 500W anode dissipation altho without forced air cooling.
> Sockets arent that common and look poorly made?
> Very similar to the QB5/1750 which conveniently fits a 4-1000A socket and
> are often available in the US as a few BCB transmitters used them.

> The GU-81M is also similar, and sockets seem to be more available but
> expensive.

> They all make excellent AM modulators (-;

> Carl
> KM1H

Thank  you for very useful notes. GU46 were rare used here because of
we  good  choice  of  another  cheap  tubes. I know a few designs with
1-2pcs of  GU46,  1 tube is able run 500-1000W, but better 500W for its long
life. It is not a big problem to find these tubes here, but sockets is
not easy to find. Local people try to make these sockets, they are not
masterpiece of course, but they work.

GU81m can be used of course, it is cheap, its socket is not a problem
(my  socket  cost  $35ea,I think it is not expensive). Sometimes it is
used without original electrodes,this make it much compact. You can
watch  plenty of pictures GU81m with sockets and without electrodes if
you google GU81m and then open the first topic.

 Dr Alex Gavva   QRO Parts Site: http://www.ur4ll.net
 KO70XG          mailto:ur4ll at ur4ll.net

Thanks for the reply Alex. I already have a pair of NOS GU-81M's and used 
sockets via friend who picked them up at Friedrichshafen and shipped to my 
son who was stationed in Germany and then via APO to me. They are currently 
modulating a 4-1000A.

That same son will be flying to Kiev in a week for about 5-6 weeks, then to 
Moscow for 2-4 weeks and then Tiblisi for a 18 month or longer US Embassy 
assignment. Possibly he can contact you and do some shopping for me. 
Diplomatic mail is cheaper than the direct way by far (-;
 He speaks, reads, and writes fluent Russian and has a MSEE degree but 
understands little about vacuum tubes except those in his custom guitar 


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