04-16-2020, 02:15 PM
I found this radio on Ebay. It is the same model my mother listened to every day while working in the kitchen. I fell asleep to it listening to WLS in my early teens. Certainly not a great radio but I have it working for nostalgia reasons.
Question for the experts among us on IF transformers with silver mica disease: I cut out the silver mica caps and installed new mica caps and the radio works. I was able to tune the transformers for the 455khz IF. However, I did not have the exact caps. Instead of 110 mmf, I used 100mmf, and on the second IF, instead of the 75 mmf, I used 70 mmf. As I said, I was able to peak the IF at 455. The question is, does the efficiency of the IF transformer suffer by reducing the capacitance of the LC circuit and increasing the inductance? The radio works ok, but is not as sensitive as I think it should be. (I have to say, though, I did not test the tubes., and I have no experience with AA5's.)
Just as an aside, I was pleased to see that this design isolated the chassis from line voltage.
Question for the experts among us on IF transformers with silver mica disease: I cut out the silver mica caps and installed new mica caps and the radio works. I was able to tune the transformers for the 455khz IF. However, I did not have the exact caps. Instead of 110 mmf, I used 100mmf, and on the second IF, instead of the 75 mmf, I used 70 mmf. As I said, I was able to peak the IF at 455. The question is, does the efficiency of the IF transformer suffer by reducing the capacitance of the LC circuit and increasing the inductance? The radio works ok, but is not as sensitive as I think it should be. (I have to say, though, I did not test the tubes., and I have no experience with AA5's.)
Just as an aside, I was pleased to see that this design isolated the chassis from line voltage.
