David wrote:

The fixed-step (10 kHz) tuner is what killed music on AM radio. You
can get a much more pleasant sound by detuning a few 100 Hz. This
PLL crap sounds like ****.

Assuming that indeed a more pleasant sound is had by detuning off the
center frequency by a few hundred Hz (Patrick was skeptical), this is
not a problem for the Channel TRF tube tuner design since I believe a
very fine tuning control will be necessary, due to both tuner warmup,
and long-term drift as bandpass component values slowly change over
time between "calibrations".

Only guessing, I think the control should vary the center frequency
for a channel by about +/- 1 khz, enough to cover the several hundred
Hz of deviation for those who think this makes the station sound
better.

Jon Noring