12-11-2021, 12:58 PM
Ok, now we know that the oscillator is running at the right frequency and agrees with the dial calibration, so the dial error must be caused by the IF not being tuned to 470 kc.
I don't think anything is physically wrong with the IF, only that the IF transformers are tuned to the wrong frequency. The compression trimmer caps in the IF cans have a large tuning range, so they are easy to set to a freq other than 470 kc.
Somehow your generator is off freq or there is some other reason the IF is different from 470 kc. You can try the suggested idea to check the second harmonic of your 470 kc generator signal by listening with your digital receiver at 940 kc.
Another thing to try is to gradually tune the IF transformers toward the correct 470 kc by tuning in a known freq broadcast station, setting the dial to where it is actually received, not where it should be. Then tune slightly toward the correct dial calibration and repeak the IF transformers on the received signal. Repeat this procedure in steps until the station is received at the proper indication on the dial. Since you know your oscillator frequency is correct, this should align your IF to very close to 470 kc. If you can't reach proper dial calibration by this method then something is really wrong with the IF transformers or circuitry.
I don't think anything is physically wrong with the IF, only that the IF transformers are tuned to the wrong frequency. The compression trimmer caps in the IF cans have a large tuning range, so they are easy to set to a freq other than 470 kc.
Somehow your generator is off freq or there is some other reason the IF is different from 470 kc. You can try the suggested idea to check the second harmonic of your 470 kc generator signal by listening with your digital receiver at 940 kc.
Another thing to try is to gradually tune the IF transformers toward the correct 470 kc by tuning in a known freq broadcast station, setting the dial to where it is actually received, not where it should be. Then tune slightly toward the correct dial calibration and repeak the IF transformers on the received signal. Repeat this procedure in steps until the station is received at the proper indication on the dial. Since you know your oscillator frequency is correct, this should align your IF to very close to 470 kc. If you can't reach proper dial calibration by this method then something is really wrong with the IF transformers or circuitry.
