09-16-2009, 11:59 AM
Well, as I have it now, 610 is at about 620 on the scale, while 1530 is at about 1500 on the scale. That appears to be as close as I can get it to work. It still seems like the bandwidth is compressed a little bit (i.e. 610 needs to move down and 1530 needs to move up). (my digital is just another AM/FM radio, so it doesn't tune beyond about 1700AM)
However, while the oscillator trimmer has a profound and obvious effect, I can't hear anything going on when I adjust the antenna trimmer. If I tighten it all the way down, there is a very slight drop in volume, but once it's at all lose, it always sounds the same. I can unscrew it to the point where the screw is ready to fall out, but you can have a station tuned in and nothing at all changes when you turn the atenna trimmer.
I looked at it physically, but to be honest, I can see why it doesn't work - I just know the oscillator trimmer works, but the antenna trimmer doesn't. I took off the adjustment screw, and saw that it appears to be a simple cap with one metal plate connected to ground, a thin clear plastic sheet (presumably the mica dialectric) and another plate that it all screws down upon. Reads a small amount of ohms between the two plates (which is apparently the resistance through the coil which is in parallel) and this doesn't change when you screw it together (so the two plates aren't shorting). But it just really doesn't seem to DO anything when adjusted along its range. I even tried adding a small piece of paper along with the plastic, and it had no audible effect. Maybe the effect just is too small to be heard - I don't know.
It works well enough I guess right now, and maybe as good as it ever did, being so simple, so I guess I'll leave it as is for now unless anyone has further advice.
However, while the oscillator trimmer has a profound and obvious effect, I can't hear anything going on when I adjust the antenna trimmer. If I tighten it all the way down, there is a very slight drop in volume, but once it's at all lose, it always sounds the same. I can unscrew it to the point where the screw is ready to fall out, but you can have a station tuned in and nothing at all changes when you turn the atenna trimmer.
I looked at it physically, but to be honest, I can see why it doesn't work - I just know the oscillator trimmer works, but the antenna trimmer doesn't. I took off the adjustment screw, and saw that it appears to be a simple cap with one metal plate connected to ground, a thin clear plastic sheet (presumably the mica dialectric) and another plate that it all screws down upon. Reads a small amount of ohms between the two plates (which is apparently the resistance through the coil which is in parallel) and this doesn't change when you screw it together (so the two plates aren't shorting). But it just really doesn't seem to DO anything when adjusted along its range. I even tried adding a small piece of paper along with the plastic, and it had no audible effect. Maybe the effect just is too small to be heard - I don't know.
It works well enough I guess right now, and maybe as good as it ever did, being so simple, so I guess I'll leave it as is for now unless anyone has further advice.
