The Amplifier on the left was initially built in 1998, but the tube I used didn't work too well in class AB/B, it was in fact a Class C tube, I eventually got the tube I'd been waiting for (4-1000A)

It has an edge wound roller inductor, instead of the usual tank coil, so it should work out quite well in Grounded Grid with 4KV on the plates. The Amplifier employs the same circuit as used in the 4-400 Amp

I also managed to get a second 4-1000A and a chimney from Bushy ZS6YQ, we traded some tubes that he desperately needed for his Collins equipment, thanks Bushy

I'm running 4 KV on the plate, so the output isn't quite what one could expect with voltages of 6KV or greater

The Amplifier on the left was built in 1997 and uses a pair of 4-400's in Grounded Grid

The circuit was taken from William Orr's Radio Handbook, 17th Edition of 1969 and works quite well with 3 - 4KV on the plates

I didn't apply any input tuning network. I use an external antenna tuner to match the transceiver to the Amp

It was extremely difficult to find components, after many visits to swap meets, and the odd Ham or two was able to get enough junk to build the Amp. My brother Pete, also provided me with a number of components

I was lucky to get some diode blocks rated at 8KV, at around 2 Amps, and an HV transformer rated at 4KV at about 2 Amp, all of which my brother Pete gave me, thanks Pete

I regulate the secondary voltage using a variac on the primary of the transformer, the supply can actually deliver 5.6KV at around 2 Amp

High Voltage Power Supply Capacitor Bank

The capacitor bank comprises twelve (12) 3300 mf 450 VDC capacitors in series, to provide approx 300 mf at 5400 volts

Each capacitor is shunted with a 150k ohm resistor. The old filter bank comprised high voltage oil filled capacitors which only provided 18 mf of capacitance