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![]() ) writes: Many years ago,Superheterodyne Shortwave Radios were all the rage,Shortwave Radios wise,that is.There were ads in magazines gloryfying the advantages of Superheterodyne.Factory made and kits were available,Superheterodyne Shortwave Radios. Superheterodyne cuhulin Maybe the newsgroup would be better if you didn't spew nonsense. If you know nothing of a topic, don't bother posting. Virtually every shortwave receiver in production today, and for many a decade, is superheterodyne. They all convert the incoming signal down to a fixed frequency for selectivity and amplification. The exceptions would be fairly obscure kits, using regeneration, or maybe some commercial amateur radio receivers or transceivers, using direct conversion (which heterodynes, the incoming signal directly down to audio). You'd have to go back many decades before you hit a point where a large percentage of shortwave receivers were regenerative. Go back forty, and some would be regenerative, albeit they'd be at the low cost end of the spectrum. Go back to the thirties, and regeneration likely was still common, because superheterodyne designs used more components and hence were too costly for many in the depression era. Go back to the twenties, and besides cost there were still bugs (the issue of images for instance), and maybe even a reluctance to move to something new. Once again, Howard Armstrong received the patent for the regenerative receiver in 1914, US patent number 1,113,149, He received the patent for the superheterodyne receiver in 1920, US patent number 1,342,885. And he received the patent for the superregenerative receiver in 1922, US patent number 1,424,065. Howard Armstrong took care of all basic receiver design beyond the simple "crystal radio" and the TRF (Tuned Radio Frequency) receivers. And took care of that by 1922. Everything that came later were variants of those three (or more like two, regen and superhet) basic concepts, incremental improvements but no fourth type of receiver. Michael |
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heterodyne 455 spurious signal on AM | Shortwave |