amirb, thanks for the info on the likely causes! I need to spend some time working through the RF operation, but this should focus my search. The frequencies are very close. Not precisely correct, but they don't look far off. They're pretty stable, but they do bounce around a bit. This is especially noticeable when I set the frequency span low.
Don, the noise floor is exactly as you describe. When I perform a preselector peak I get:
2.2GHz: -1.7dB
4: -1.7
5.7: -3
5.9: -2.8
8: -3
12.4: -5.5
12.6: -14
18.5: -13.5
18.7: -13.5
20: -11.9
That's as high as I can go. I'm not sure if this is normal, but the amplitude moves around a lot during "peaking!". The cable is of high quality, but is only rated to 18GHz.
