The work was done by a Certified McIntosh Technician (who returned all of the replaced tubes and nuvistors, all of which had tested weak or bad), and then reworked (as I watched) for two-hours employing an FM signal generator and oscilloscopes to compare the wave forms. The three-gang tuner was cleaned and aligned, and all of the other components inspected and the connections checked and tightened where appropriate. We are scratching our heads, but the bottom line is that over 100 MHz, the FM MPX works only marginally. He is not satisfied with the result at all. As mentioned, below 100 MHz, the sound truly is remarkable. Do you have any additional ideas as to what we might check?
Thanks for the reply.
Thanks for the reply.