John (xrhonda91) and I have both used BAT-46 diodes to replace 1N34 diodes with excellent results. I've used the BAT-46 for AM detectors, and FM ratio detectors.
I recently found out about another low Vf Schottky diode, the 1N5819. The BAT-46 is a 100V small signal fast switching diode with a 6pf capacitance. The 1N5819 is a 1A 40V power rectifier with 110pf capacitance.
While the 1N5819 has a lower Vf, the BAT-46 performs better as an AM detector in my test radio. The 1N5819 weak signal audio level was about half of the BAT-46. I did not notice any difference with stronger stations.
I am curious if anyone else has tried the 1N5819 and how it compares to other diodes, as I've only tested it with one radio.
The Vf is slightly lower for the 1N5819 compared to the BAT-46 and 1N34a diodes I tested.
Code:
Current BAT-46 1N34a 1N5819
0.1mA .20V .18V .14V
0.25mA .23V .21V .16V
0.5mA .25V .24V .18V
1.0mA .27V .26V .20V
2.0mA .30V .29V .22V
4.0mA .34V .33V .24V
Leakage @9V 0.1uA 0.5uA 1.2uA