haskellbob
- Apr 13, 2020
- 21
- Joined
- Apr 13, 2020
- Messages
- 21
Hello.
I have a Heathkit AR-15 receiver which has a procedure for aligning the multiplex circuit, written in the manual. I follow this procedure, the last step of which is to adjust a choke until the sound goes from garbled to clear. I have done this several times. Each time the FM works fine for a few days, and then it gets garbled again. So I adjust the "garble removing" choke until the sound is clear and... after a few days, the same thing happens. I think there is some kind of a drift?
I thought maybe the core of the choke was physically moving (it seems a far-fetched idea but it was all I could think of) and, since I had another choke to replace the original one if things went badly, I inserted a drop of glue in the choke (having adjusted it first). Well, guess what?
It's a good thing I had another choke to swap in. And I adjusted that one, and after a few days... you guessed it!
I have to think the problem is not with the coil at all, but with some other component that is drifting or changing its value over time.
I have the schematic, although I'm not finding any way to attach it. I will if I can.
Does anyone have any ideas about what could be causing this? I sure would appreciate being pointed in the direction of the source of the problem. Thanks in advance.
Bob
I have a Heathkit AR-15 receiver which has a procedure for aligning the multiplex circuit, written in the manual. I follow this procedure, the last step of which is to adjust a choke until the sound goes from garbled to clear. I have done this several times. Each time the FM works fine for a few days, and then it gets garbled again. So I adjust the "garble removing" choke until the sound is clear and... after a few days, the same thing happens. I think there is some kind of a drift?
I thought maybe the core of the choke was physically moving (it seems a far-fetched idea but it was all I could think of) and, since I had another choke to replace the original one if things went badly, I inserted a drop of glue in the choke (having adjusted it first). Well, guess what?
It's a good thing I had another choke to swap in. And I adjusted that one, and after a few days... you guessed it!
I have to think the problem is not with the coil at all, but with some other component that is drifting or changing its value over time.
I have the schematic, although I'm not finding any way to attach it. I will if I can.
Does anyone have any ideas about what could be causing this? I sure would appreciate being pointed in the direction of the source of the problem. Thanks in advance.
Bob