audmod01
Super Member
OK, results: I do now see a definite peak in the 10.7mHz signal by adjusting the primary of the Mixer output IF coil. The secondary does also. I do also see that among the many stations that I pick up on the air, more of the stations now show close to level 2 on the signal meter (full limiting at that level). I picked up some more selectivity, but not any more indicated gain at the level meter. I checked the parts list and the two level meters do not have the same part number. They differ by one digit. Externally I only see that one has its needle pointing to the right (FM meter) and the other points to the left (AM meter). In other words both meter's pointers point toward the center of the dial. I suspect that both have the same movement and internal resistance etc. and so one more check I am going to make is to temporarily disconnect the AM detector feed to the AM meter and lift the lead going to the FM meter and run a clip lead from the meter out connection point to the AM meter input to compare and see if the detected level of the FM is higher on that meter.
Another thing I might do is to use my scope at the IF frequency and input a low level 10.7mHz signal to the mixer grid again and look at gain stage to stage. There must be at leas one or more stages that are not providing gain for whatever reason unless the level meter is lying to me.
Every IF stage up to the FM level meter shows a peak at the FM level meter which appears to be a sharp peak the best I can tell so far. I will try again tomorrow to see if I notice anything else.
Joe
Another thing I might do is to use my scope at the IF frequency and input a low level 10.7mHz signal to the mixer grid again and look at gain stage to stage. There must be at leas one or more stages that are not providing gain for whatever reason unless the level meter is lying to me.
Every IF stage up to the FM level meter shows a peak at the FM level meter which appears to be a sharp peak the best I can tell so far. I will try again tomorrow to see if I notice anything else.
Joe