02-04-2019, 04:36 PM
Today I stumbled onto something that I want to run by everyone in hopes that someone can help me understand what is happening. This may be a little long-winded...sorry, I just want to give as much info as I can.
I decided to try to eliminate the function switch as the problem. It really acts like something isn't being connected properly when switched to FM. So I connected jumpers to the appropriate places...9 jumpers in total. Eventually, I decided to take off all but 3...those that switch in the FM oscillator circuit. I've not ruled out the switch as a problem completely, but I really don't think it's the problem.
But in the process of doing this testing I thought a heard a faint station on the speaker, so I held it up to my ear and it was a station, 104.5FM. The dial was all the way at the low end so I scanned it to the top. I received the same station all the way up the dial and it was strongest at the top end. At full volume it's loud enough to hear it from a few feet away, and distorted.
I had my generator on and when I changed the frequency the signal went away. So I did some experimenting and found that I could receive 3 or four stations by tuning my generator to different frequencies, and the tuning condenser on the radio didn't change the tuning at all.
Ok, now the interesting thing. I received 104.5 when my generator was set to roughly 95.4, and I received 102.9 when my generator was set to roughly 93.8. In each case the difference is roughly 9.1mhz which is the IF frequency on the radio. So it seems like the generator is acting as the local oscillator, and the tuning on the radio is ineffective.
Can someone explain to me what is happening and what I should do next?
Thanks,
Rich
I decided to try to eliminate the function switch as the problem. It really acts like something isn't being connected properly when switched to FM. So I connected jumpers to the appropriate places...9 jumpers in total. Eventually, I decided to take off all but 3...those that switch in the FM oscillator circuit. I've not ruled out the switch as a problem completely, but I really don't think it's the problem.
But in the process of doing this testing I thought a heard a faint station on the speaker, so I held it up to my ear and it was a station, 104.5FM. The dial was all the way at the low end so I scanned it to the top. I received the same station all the way up the dial and it was strongest at the top end. At full volume it's loud enough to hear it from a few feet away, and distorted.
I had my generator on and when I changed the frequency the signal went away. So I did some experimenting and found that I could receive 3 or four stations by tuning my generator to different frequencies, and the tuning condenser on the radio didn't change the tuning at all.
Ok, now the interesting thing. I received 104.5 when my generator was set to roughly 95.4, and I received 102.9 when my generator was set to roughly 93.8. In each case the difference is roughly 9.1mhz which is the IF frequency on the radio. So it seems like the generator is acting as the local oscillator, and the tuning on the radio is ineffective.
Can someone explain to me what is happening and what I should do next?
Thanks,
Rich