- 2025
- Mar
- 25
The Heatkit AF-1 Analog Frequency Meter, Part 6b - Testing the power supply.
The power supply for the Heathkit AF-1 has been re-done, and all of the relevant components replaced. I’ve checked my work, and don’t see anything that would cause the smoke to be let out of the device. Therefore, it’s time to plug it in. It, of course, goes on the isolation transformer/variac for safety, with the master power switch close at hand.
First thing to do is identify the test points I need to check. Input voltage and Output voltage are going to be important here:
As part of the rebuild, terminal strips were added for various parts. That made it easier to lay the new parts in (since the capacitor’s pins are no longer there,) and it makes it easier to pick voltages off.
Input voltage is nothing unusual.
Ripple is now as expected. 120Hz @ ~1VPP. Certainly much better than the 11VPP we had before.
Voltage after the regulator is as expected as well.
And there’s the purple glow of the VR150 tube.
I’m planning on rebuilding the filter section of the unit before proceeding. Stay tuned!
Next part of this series: https://wereboar.com … building-the-filter/
Previous part of this series: https://wereboar.com … -6-the-power-supply/