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.".

I am going to try and drive the detector diode in
my R2000 with a ~20K resistor feeding the junction
of to force the Ge diode slightly into conduction.
(for a diagram of the R2000 please see:
http://www.qsl.net/kc7bum/schematic-1.jpg
for a diagram of the R2000)

But I would prefer to find a diode with the lowest
Vf possible. Back in the mid 1970's GE had a diode
with a very low Vf, but I can't remember the name.

I think I would do away with the simple diode envelope detector and
substitute something more sophisticated. In my homebrew RX I am using an
NE602 as a multiplier- this from Wes Hayward's latest text- Experimental
Methods in RF Design.
Another approach I have used with good fidelity is an MC1330 (?) video
detector. Finally, see:
http://www.amwindow.org/tech/htm/alowdisdet.htm
for a nice treatise on the shortcomings of classic diode AM detectors.

Dale W4OP