[TMC] SBT-1K

[LARRY D GODEK]

Kind of curious.  The manual for my SBT-1k says that i should get 1KW output on CW and RTTY and 500W on AM (DSB with carrier and low level modulation).  Doesn't compute.  Even if i was to keep it at 1/4 KW on am.
 
1 KW output on CW would mean it has to run 1500W min (figuring 66% eff) in order to get 1 KW out.  CW should be classified as ICAS and not CCS.  If i can run 500W output in AM mode (DSB with carrier) then i should be doing 2 Kw input if you use the 50% carrier and 25% in each sideband rule.  But the tube is supposedly only a 1KW tube which would cause you to run the amp at 250W output and not 500.
 
RTTY would be harder on the tube because you have a tone applied continuously. 
 
Either way the ebst i can do is about 600W out on CW with my 8295A.  I tested several others today and found all of them to be defective dither in the screen or plate circuits apparetly internally.  Would like to find a new tube that i wouldn't have to take out a mortgage on the truck in order to afford it.  Nix on any PL-172 types.  Worse comes to worse i could change it out along with the socket to a 4CX1500B.  Only requires a couple additional parts changes then.. Got several of those NIB.
 
This things sets here at 250W output and doesn't even have warm air coming out the exhaust vent.  Gotta becareful though cause when you get to the 50 ma Ig mark then it's close to dumping.  Requires about 380 ma Ip to get 600W output in CW mode.  Oughta make some noise..
 
Larry
W0OGH