On Friday, September 3, 2021 at 5:36:16 PM UTC-4, Phil Hobbs wrote:
Michael Terrell wrote:
On Sunday, August 29, 2021 at 10:07:35 PM UTC-4, Brian Gregory wrote:
Suggesting silicon diodes as substitutes for a germanium signal diode is >> pretty daft too.
Hot carrier or Zero bias diodes work well, and have better specs but they aren't cheap. They are made for microwave mixers and detectors
With a bit of bodging, something like a BAT15-03 (<$1 in onesies, 21
cents in reels) ought to work at least as well as a 1N34A, assuming that
a 4V rating is enough, which it ought to be for an RF detector. (1N34As
work up to something ridiculous like 60V).
I suppose the 1N271 is obsolete, as well? Microdyne had switched to them from earlier pat numbers in the late 1990s.
There are Ebay listings for 1N34 diodes. I had a pound of them, from Poly-Paks, but an animal dug a hole under the wall into my shed, and used them to make a nest. Needless to say, the several thousand diodes had their leads rusted away. I still have
some that were salvaged from some '70s era computer PC boards. They were daughter boards with individual flip flops, and they had silver mica capacitors. I can't imagine the price of something like that, back then.
Another trick is to DC bias a diode to give it closer to a zero volt forward drop. This was done in some radios in the early days to improve sensitivity. I had to scratch my head the first time I saw that trick, with a 6H6 dual diode vaccum tube.
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