Andreas DL1AJG in Germany sent the above video to me. Andreas is the fellow who ran the course in which his university-level students built direct conversion receivers.
I like the presenter’s technique. But it would have been cooler if he actually used a chunk of Galena or Iron Pyrite, with a cats whisker. (I still have some of the Iron Pyrite that Mike KL7R gave me many years ago.) I think that all radio amateurs should (as a rite of passage) actually poke a crystal with a cats whisker in search of a signal. Like here:
Thanks Andreas!
I have found that the spring out of a ballpoint pen makes a great cats whisker. I have used one with an actual piece of galena from Galena, Illinois. Literally tons of it out there to grab.
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