[Heathkit] SB 200 with Harbach mods has problems

[John King]

I have an SB 200 that the Harbach power supply upgrades (?) have been installed in and it developed a problem where R8 burned and after replacement, the multi-meter reads zero in all positions with only a SLIGHT kick when switched to plate and high voltage then instantly returns to zero after the slight kick.

When the multi-meter is placed in the "plate" position and the relay is energized, the meter plate current position PEGS but there is no indication from sound of tubes pulling current. It is believed that this might be a meter multiplier problem. When the relay is energized by grounding the relay there is NO meter indication in the Grid , HV, or relative output positions.

I am in Montana for the summer and have ONLY a multimeter (Fluke) with me and the maximum voltage it will read is about 1000 volts. I find the documentation from Harbach to be confusing.

If you have had serious trouble shooting experience with the SB 200 with Harbach mods in power supply, I would greatly appreciate the benefit of your knowledge and experience. I am not sure that installation of the Harbach power supply rectifier board is a great idea. What do you suggest be done with very limited test gear? Your help will be appreciated. 73, John, K5PGW



























about 1800 vdc in the plate current position, not in the plate voltage position.