Hi Steve, I just finished duplicating your Class H modulator design and it works great. It is a big improvement, with respect to setting up, compared to the previous series modulator. I am now building a power supply so that I can get a little more power out of my Class E transmitter. I was using a pair of 50 volt regulated supplies that are current limited at about 5 amps, so I wasn't able to fully modulate it at much over 75-100 watts of carrier.
Since I will now have a bit more current available, I decided to put in an over current trip circuit as you use in your power supply. I built the current trip circuit, but can not get it to trip when I put 1-2 volts across the 0.1 ohm resistor. I don't have it connected to the power supply, but am using 1 or 2 AA cells connected across the 0.1 ohm resistor. I wonder if the emitter of the TIP29a should go to ground, rather than the floating sub-assembly. Since the TIP29a is an NPN transistor, the base needs to be more positive than the emitter for it to turn on. With the base at the high end of the 0.1 ohm resistor, I don't think it would ever go positive. I've never been good with multiple grounds at different potentials, so I might be misunderstanding something. Well, thanks again for all the consultation over the past year while I got my transmitter going. I see that there is a lot of interest in your kit and suspect that the kit will greatly increase the high fidelity AM signals on the bands. I plan to build something for 160 M AM and originally planned to make something with a pair of 100 THs (I like the glow), but Class E would be much simpler. Regards and 73, Fred WA0GMH
