sean...Your comment about unit-to-unit differences was very true in the days of analog tuners, where exact alignment of multiple stages of tuning circuits was as much art as science. With today's digital tuners and phase lock loop chips I had the impression that unit-to-unit differences were small, although I must admit that I never had a bunch of the same models on hand to compare. I did have a tuner where the biFet front end RF amplifier transistor was blown, (so the RF gain was 1) and the tuner still worked fairly well. I suppose that RF gain variations could occur and produce the effect you remark upon.
