- 2025
- Mar
- 26
The Heatkit AF-1 Analog Frequency Meter, Part 9 - Testing the rebuild.
It lives! After a quick check of my work, I plugged the device in to the isolation transformer and received this wonderful sight:
For testing, I used the manual’s suggested 3/4 scale for all bands. Here’s what I discovered - everything except for the 300Hz band will dial in as expected, with the parts that are currently installed in the unit. I was able to get close to the specified value on the 300Hz band, but I ran out of potentiometer before getting to the right value.
So - in order to get where I need to be, these are the potentiometers that should be specified:
100Hz - 200Ω
300Hz - 10kΩ
1Khz - 200Ω
3Khz - 5KΩ
10Khz - 200Ω
30Khz - 5KΩ
100Khz - 200Ω
The device probably could have sufficed with just the four 1xxx bands.
I’m currently waiting on a 10kΩ potentiometer of a similar style to what I purchased for the other bands, as soon as that arrives I’ll install it and do a final test and calibration post, as well as a wrapup. I’ll have a final corrected schematic at that point, stay tuned!
Next part of this series:https://wereboar.com … l-assembly-and-test/
Previous part of this series: https://wereboar.com … ding-the-rest-of-it/