[MRCA] TBW and the 803

[Ray Fantini]

The PA tube is a mystery to me, have tried and tried to damage the 803
but it won’t die! When I first got the transmitter going collected up
couple spare 803 tubes because I thought I would need them but still on
original tube. The transmitter runs full screen voltage on the PA in
tune mode with no plate, always thought that was supposed to damage a
tube but has not hurt it yet. The IPA grid drive is always strong but
that has not been an issue yet, do have a problem getting IPA grid
current above 5 ma or so epically on higher frequencies but 2 to 5 ma
appears to be plenty of drive from the IA. Have had issues with finding
strong 837 tubes but the 803 for a sixty year old tube just goes on and
on. I am only running about 1.25 kV on plate instead of 2.0 kV but still
way impressed with old GE transmitting tubes. Anyone have a TDE or
anything else like that works the tube harder and what have been their
results?
Ray Fantini KA3EKH


>>> mac <w7qho at aol.com> 06/05/09 5:47 PM >>>
Ray,

Nice video.  Odd, though that the TBW (and GO-9) seem to be designed  
to significantly over-drive the PA.  Note that you were getting almost  
40ma where the book calls for 25ma CW and 15ma phone.  I noted the  
same thing when i fired up a TBW a few years ago.  Any thoughts?

To see some of my video stuff search on w7qho.
73,
Dennis D.  W7QHO
Glendale, CA