Just wanted to share this
I never cease to be amazed when I watch videos from the old days before technology made things easy for the every day person. I've seen videos for changing a crystals frequency by sanding them or putting them in acid, I've seen wavelength and tuning measurements with a lecher line and a neon bulb, I've seen single conductor transmission lines that have less loss than coax or twin lead, and now I believe I've seen it all... An optical lens made of glass focusing RF energy!
This particular video starts out very boring to the average wire nut, but the second half is an excellent demonstration of reflection, refraction, diffraction, and standing waves. Just thought I would share the link for those interested.
https://www.youtube.com/watch?v=Vwjcn4Vl2iw&t=636s
EDIT: "The way things used to be done" is almost worthy of its own section on the forum!
Last edited by brandon lind; Fri 9th Aug 2019 at 07:41.
Oh wow, I had forgotten about those. As a kid, I used to watch the Royal Institute Christmas Lectures. If I remember correctly, they were shown on TV during the school summer holidays on BBC2.
As for re-tuning crystals: remove the metal casing and a little bit of pencil lead (OK, graphite) would knock it down a few kHz.
He's not a patch on Irving Finkel
nice one, enjoyed it
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