[ARC5] SS Cathode modulator.

[Kenneth G. Gordon]

Actually, from reading the blurb which accompanies the circuit, it would 
appear that all it does is control the cathode current of the tube(s) being 
modulated.

In other words, Q-4 is an audio-controlled variable resistor in the 
cathode-to-ground circuit. 

The 6 volts has nothing to do with it there. That simply provides operating 
voltage for the other 3 transistors. Current drain from the 6 V source is 
minimal.

The other 3 transistors simply drive the base of Q-4 and are connected the 
way they are so that they present a high-impedance at the INPUT.

R-1 sets the quiescent current through Q-4 at no modulation.

Although I am still not sure about it, I'll bet it does work.

As I said, I'll bread-board one of these up and try it out as soon as I can.

If anyone else feels like trying it, go ahead.

Ken W7EKB