K7ITM wrote:

There is such a thing as TOO HIGH a loaded Q. Let's say you start off
with a coil with unloaded Q of 500, and couple lightly to it with your
circuit (antenna and detector), so the loaded Q is 250. That means the
bandwidth at 3dB points, if you tune a station at 1MHz, is 4000Hz. If
you've tuned to the center of the station, your demodulated bandwidth
will be only 2kHz. Since the rolloff is gradual with a single-tuned
circuit, voice should be OK, but you'll be missing out on a lot of the
highs. (Mind you, it's not easy at all to get an unloaded Q of 500 at
1MHz!)

Ok, I'm back with a couple more questions, since y'all are so
informative... I know it's not a true xtal set if I add an amp, but
wouldn't the best way to minimize the drop between the unloaded and
loaded Q be to add an amp? With a transistor/op amp, it seems that you
could tailor the load imposed on the tank circuit so that it's minimal,
while it seems a headphone load would be pretty significant (depending
on the headphone)...?

Also, I've seen some schematics with transistor-based and Op amp-base
amplifiers. Generally speaking, are there advantages/disadvantages to
either transistors or op-amps as the first-stage RF amplifier?

Thanks again for all the information!
Dave