I just got a mail from a SB1000 owner who gets the normal 750 -900 watts out with his old used tube. But wíth two different new EIMAC tubes he only gets around 200 -250 watts out and both tube
? The 3-500Z is supposed to get red. Hard to say. If you think it's oscillating, look around 150MHz with a wavemeter. Also, unsolder one end of R-supp and measure the actual resistance. An open R is
Sounds like bad tubes. Very very doubtful. The way you can find a parasitic is to key the PA without drive so it has idling current, and rotate the tuning control through it's range while looking fo
Yet another old wives' tale. This is how you test for instability at the operating freq. To generate the requisite damped wave anode circuit ringing, it takes transient anode currents. Owners who ha
I agree, I've seen exactly this in an AL80B whose 3-500Z had a grid/cathode short. 73, Vic, K2VCO Fresno CA -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administ
With a grid/filament short, there would not be any output. later, Vic - Rich..., 805.386.3734, www.vcnet.com/measures. end -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contest
I'm not sure of the mechanism. There is certainly part of the grid which is not touching the filament, and the whole structure has a certain amount of inductance, allowing for some voltage to appear
The grid is a welded cage. There is only one part. Very little. The grid cage is grounded in three places. With a shorted grid, one has zero volts bias. This typically doubles ZSAC. This is the wors