I am very inexperienced.
I am a HAM, I just got a HA-10 amplifier that has been modified. The half wave tubes were replaced with a string of Z5U .01 ceramic caps in parallel with 1M ohm resistors and unknown diodes, four sets on each side.
Please see the pictures and schematic.
There is no visible identification on the diodes, the caps are Z5U .01 2K. The string is off a 3500 volt transformer that powers this string to the transmitter tubes 4 of 811a's. I want to replace it with new parts because the wires have black dust on them, I am guessing from running to warm. It is a 1 kW amplifier.
Can anyone PLEASE help me and explain what this genius did maybe 50 years ago?
I want to build a nice little board with the proper diodes/diode and caps to replace this cardboard setup. I have wiring diagrams and some specifications. I do not have the knowledge at this level.
Any comments or suggestions are appreciated. I have a drawer of 25amp 50 volt full wave rectifiers and would love to use them. I am not sure how I would without it being partly guessed.
Correct, I looked with magnifying glass and bright light. If it is there it has long burnt out of eyesight range. You should be able to zoom in on the photo, I may have made it too small, but the only thing I could get was numbers on the caps, and a guess on the code of the resistors because the colors are not according to text book. The two tubes that were replaced were 866a half wave. I will send specs in a few minutes. Thanks, I hoped to just buy the same and rebuild the existing setup.
Correct, I looked with magnifying glass and bright light. If it is there it has long burnt out of eyesight range. You should be able to zoom in on the photo, I may have made it too small, but the only thing I could get was numbers on the caps, and a guess on the code of the resistors because the colors are not according to text book. The two tubes that were replaced were 866a half wave. I will send specs in a few minutes. Thanks, I hoped to just buy the same and rebuild the existing setup.
Best Answer
The Heathkit Warrior HA10 kW amplifier power supply used a transformer with a 3400V center tapped secondary, followed by two 866 mercury half-wave rectifiers connected in a full wave center tapped configuration. Each rectifier had 1700V on its anode.
Many owners of this and similar equipment replaced the 866s with silicon diodes when the 1kV diodes became readily available at low cost. The method used was to string multiple diodes in series, each shunted by a 500k-1M resistor in parallel with a 0.01uF ceramic disc capacitor, usually Z5U dielectric.
Most likely, what you have are 1kV, 1A diodes, such as 1N4007. Better replacements are available today, but you would be safe using this same diode in that configuration for the HA10.
Before you replace the diodes, I suggest you replace the filter capacitors and test the choke for shorts.