[AMPS] 3CX800

[Peter Chadwick]

Rich says:

>?  ZSAC can be set quite nicely with E-screen.  The primary consideration 
>is to set the dc grid potential so that virtually zero grid current flows 
>with max. drive.  

Sure. But that affects the peak plate current. Having the screen volts set
so that the correct peak plate current flows at Eg = 0, and then setting the
bias for correct zero signal current is surely better?

The business of 'overdrive' caused by reliance on ALC (which is quite likely
defective in design) is another matter.

>The simple solution is to choose a grid-term. R that is the most
appropriate >for use with the exciter/tube combo

Yes. With 3 6146Bs driving a 4CX1000, 50 ohms isn't too bad: 25 would be
better. (the tx on 12metres is a bit short on output) But a 3dB pad and 50
ohms is easier, especially when you have a fairly large number of high
wattage carbon stick resistors to hand.

73

Peter G3RZP



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