03-21-2023, 07:02 AM
I can finally declare victory.
I hooked up a scope and the oscillator coil resonated at 2.7 mHz, 2.2mHz and 2.5mHz. Each time I took a measurement I would turn the signal generator to 1.4 mHz and would tune the radio to see how far off the dial was. Then when I checked the resonant frequency again, it resonated at a different frequency.
I removed the coil and found that the mounting bracket screw that attached the coil to the chassis and provided the ground connection was slightly loose as was the rivet that held it to the coil. I sanded the bracket and the chassis at the points of contact and reflowed the solder at the rivet. Wired it back in and Shazam, it oscillated at 2.158. The trimmer brought it up to 2.185 and the dial now agrees with what I set on the signal generator.
Thanks to Arran and MrFixer55 for your help. This was an interesting problem and a good experience.
I hooked up a scope and the oscillator coil resonated at 2.7 mHz, 2.2mHz and 2.5mHz. Each time I took a measurement I would turn the signal generator to 1.4 mHz and would tune the radio to see how far off the dial was. Then when I checked the resonant frequency again, it resonated at a different frequency.
I removed the coil and found that the mounting bracket screw that attached the coil to the chassis and provided the ground connection was slightly loose as was the rivet that held it to the coil. I sanded the bracket and the chassis at the points of contact and reflowed the solder at the rivet. Wired it back in and Shazam, it oscillated at 2.158. The trimmer brought it up to 2.185 and the dial now agrees with what I set on the signal generator.
Thanks to Arran and MrFixer55 for your help. This was an interesting problem and a good experience.
Sometimes I wonder whether the world is being run by smart people who are putting us on or by imbeciles who really mean it.
