wrote in message
oups.com...
Almost all AM detectors use Germanium diodes.
This link shows an interesting alternative:
http://www.wsdmag.com/Articles/Print.cfm?ArticleID=8628
Ge diodes have a typical Vf (forward conduction volage)
of .4V.
"Silicon Schottky diodes are commercially available
in four different versions. They offer forward
voltages of approximately 600 mV for high barrier,
330 mV for medium barrier, 280 mV for low barrier,
and 180 mV for zero-bias detectors.".

True the Schottkey diodes will have a lower Vf than
your standard garden variety germanium. You will also
have to take into account that the rcvr will be more prone
to hear more man-made interference and also the AGC will
still be active and possibly negate any gains in sensitivity.
Not sure if they will work at the lower freq's well as they are
designed for microwave uses although some do run in
the RF-ID range of 36 MhZ.
A good experiment project but methinks you would be
better off with an external FET amplifier or high gain
directional loop antenna for BCB Dx.

see these for datasheets and app notes:

http://www.microwaves101.com/encyclopedia/detectors.cfm

http://www.spelektroniikka.fi/kuvat/schot8.pdf

http://www.findarticles.com/p/articl...46/ai_17990746