Use of Diode Mixers & frequency-hopping 1926!

[Tom WA3KLR]

While looking through the April 17, 1926 issue of Radio World for another reason, I spotted a one-page article on page 6 titled 'A 5-Tube Super Receiver'. The set has a mixer stage, local oscillator, 2 i.f. amplifiers, and two audio stages.  The receiver incorporates 2 crystal detectors, the first is the mixer and the second is the AM detector.  I had seen many years ago, many times, the mixer in a single-conversion superhet schematics referred to as the first detector.  But this is the first I've seen a crystal diode detector actually incorporated as the 1st mixer!

https://worldradiohistory.com/Archive-Radio-World/20s/26/Radio-World-1926-Apr-17.pdf

The other reason I was first looking through the issue was due to a thread on frequency-hopping (who was first?) in the EEVblog forum for ham radio. On page 15 of the Radio World issue, in the upper right corner is a mention of frequency-hopping by a Polish inventor. Various patents go back to Tesla and others, not just Hedy Lamarr in 1941, and more patents later of course.

[WU2D]

Tom, in the late 90's when I was still at ADI, I got to take a course in Spread Spectrum from Robert Price, a Fellow at Raytheon. This was one of those one night over several weeks IEEE courses taught at a Raytheon facility in Boston. Wow that was a course in SS history and he debuted the Hedy Lamarr story which he first published in Argosy magazine. He also showed the SIGSALLY phonograph DSSS HF system used between FDR and Churchill.

[Tom WA3KLR]

Here's the frequency-hopping history article referred to in the EEVblog on spread-spectrum:

https://www.americanscientist.org/article/random-paths-to-frequency-hopping

SIGSALLY phonograph DSSS HF system - I'm not familiar with this, I will have to research!

[Opcom]

Very interesting to see commentary on its progress. How many hams are using frequency hopping?