Using Schottky diodes in AM detectors
 

Schottky and similar diodes have a much lower diode drop, even lower than germanium diodes. Some can be as low as 0.15V. Which would make for a decent detector for weaker signals. Schottky diodes have internal capacitance, but it's about the same or less than silicon detector diodes. . A quick way to tell if a Schottky diode would work in your radio is to connect it in parallel with the existing silicon diode (0.7V drop). However, the AVC circuit may get out of balance with the lower diode drop diode. Using the old silicon diode just for the AVC circuit makes it work as it did before. This also makes for a better audio detector circuit, as the back bias from the AVC cap will not be seen by the audio detector circuit. So we have two diodes, a silicon diode for the AVC, and a Schottky diode for the audio signal. This should make for better detected sound from weaker stations.

G'day mate, sadly there is more to it than appears at first sight. There are 'schottky's and schottky's'. I use the BAT 46 schottky 'germanium diode equivalent' diodes as general purpose AM detectors with excellent results however other schottky's like the IN5711 are perfectly worthless as AM detectors unless voltage bias is used!

Voltage drop isn't the full story unfortunately. Schottky's do have advantages like a complete lack of carrier storage effects and minimal leakage. For what it's worth they are also very low noise. Regards, Felix (vk4fuq) aka catman.

As I'm using "junk box" devices, many are surface mount without any readable or meaningful markings, I've been doing the test (holding it in parallel with the old diode) to see if that new diode will improve reception or not. As I can't tell which variety of schottky diode it is.

I want to know something from your discussion. Why Schottky diode is preferred for the AM detector?
Also what are specifications for the circuit of the Am detector with the schottky diode?
What are other applications of this diode and for what rating of circuits it is suitable?

https://www.7pcb.com

Mainly for the low diode drop. Regular silicon diodes have around 0.6V, the diodes I used have lower drops like 0.2V, which should make for better detection of weak signals.

Felix Catman is better versed in this area, I'm more of a hardware hacker, trying various candidate diodes until I get one that works well. (touch it across the spot where the diode would be soldered, but not solder it yet). Better knowledge would save time. :D