[Amps] New 4-1000 Tubes ?

Alex Gavva ur4ll at ur4ll.net
Mon Jan 7 10:12:41 EST 2013

Hello Hsu,

You wrote 7 января 2013 г., 16:32:17:

> Why few amp manufacturer use GU-81M,?it is cheap and rugged.

> -----原始邮件----- 
> From: Alex Gavva
> Sent: Sunday, January 06, 2013 5:02 PM
> To: Carl
> Cc: amps at contesting.com
> Subject: Re: [Amps] New 4-1000 Tubes ?

> 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

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We  had  plenty  excellent  tubes  and people did not pay attention to
GU81m earlier.  Now  situation  is  different , it is very big problem to find
cheap  GU74b,84b,78b,etc and GU81m now in use. You can watch 2 GU81m
design made by local ham Anatol, UR5CX:   http://www.cqham.ru/pa83_12.htm

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

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