The AM Forum

Hello All!

     I was told by a freind, long time ham, and long time AMer, that once you use a high power tetrode in grounded grid service, that thats all its good for.

     He said that the tube will draw current, dip, but will not put out any power.

     Is he full of it? My closet full of 4-1000's would like to know!

Tnx,

  " Is he full of it? My closet full of 4-1000's would like to know! "

No he's not, they are almost worthless. Send them to me. I make night lights from them. I'll pay you $8.99 for each unbroken one your closet holds.  Trust me. The check will be in the mail.


klc

Some high power tetrodes are not suitable for grounded grid and they are damaged by trying to operate them in that manner, maybe that is what your friend is thinking about.  But they won't put out power in any configuration once damaged by grounded grid operation.  

4-1000 tubes are well suited to grounded grid but if the tube is still operational it will also operate just find\e in traditional grounded cathode, grid fed operation.  

Now of course once a tube has been used for SSB it will never be able to produce a proper carrier again :)

Make sure to pack them well.  Broken filaments resulting from UPS/Fedex destruction techniques and procedures won't light up, making them worthless as night lights. Other damage to the internal structure would make the aesthetically displeasing even if the filament did work.  Better to pick them up personally or have them hand delivered.

Carefull!   I had a friend run a  Flex radio into a pair and now the 4-1000s are so smug they wont output with any other exciter.

C

That Eimac and Orr article on the GG 4-1000 amp, and also the Elenco Commander with 6KV plate volts/4KW PEP input seem to show good uses for 4-1000 in GG.
Eimac would have said something if it were the case that they were ruined by GG service.

Eimac published GG specs on the 4-1000A. They really spank the monkey at 5KV. I had my 4-1000A on a BC610 transformer with a full wave bridge on 10 meters. The plate was glowing almost yellow.

It's possible to exceed grid dissipation in gg service and never know it with typical homebrew stuff using tetrodes. 
Maybe your friend has run into that.