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Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only. |
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2nd Mar 2018, 5:47 pm | #1 |
Rest in Peace
Join Date: Mar 2006
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When & where was the first Superhet produced?
The question may have been asked and answered before, but I wonder when & where, as per thread title, the first such radio (perhaps I should say 'wireless') was manufactured & sold. Maybe superhets are almost as old as broadcasting, or perhaps the set referred to as a 'supersonic heterodyne' in a new thread started today (2nd. March 2018) was, at least, one of the first of it's kind. A supplementary question might be 'when was the range 455-470kHz first adopted as the standard I.F. for broadcast band receivers? I know that quite a few pre-WW2 radios use I.F.s in the 100-120kHz range.
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2nd Mar 2018, 5:54 pm | #2 |
Dekatron
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Re: When & where was the first Superhet produced?
There is a write on Wikipedia.
https://en.m.wikipedia.org/wiki/Supe...odyne_receiver
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2nd Mar 2018, 5:56 pm | #3 |
Dekatron
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Re: When & where was the first Superhet produced?
https://en.m.wikipedia.org/wiki/Supe...odyne_receiver
Low IFs made getting good gain and selectivity easier with early valves, albeit at the expense of poor second channel (image frequency) rejection. IFs around 450-470 kHz appeared in the mid thirties. They were conveniently in the gap between LW and MW broadcast bands and gave reasonable image rejection performance on those bands. Edit: Bit slow off the mark!
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2nd Mar 2018, 6:03 pm | #4 |
Dekatron
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Re: When & where was the first Superhet produced?
Superhet IF took some time to get standardised in the 450-470KHz range for broadcast sets. I've seen some odd radios with an IF of 380KHz and the famous R1155 receiver used 560KHz as the IF, which turned out to be problematic because aircraft at high altitude were often 'line of sight' to the Athlone medium-wave transmitter on 566KHz meaning that IF breakthrough was a big issue until filters were fitted.
As you say, the 120KHz range was popular with early superhets, though that gave poor MW-band image-rejection unless some sort of 'bandpass' tuning-arrangement was used - either two very-loosely-coupled tuned circuits tuned to the frequency you wanted to receive, or in some cases the bandpass-arrangement used a parallel-tuned circuit at the frequency you wanted and a series-tuned one tuned to the image (to short the image-frequency to earth) - this latter type made 'tracking' alignment rather tricky! A lot of US car radios used an IF around 262KHz which may sound strange until you remember that there's no LW broadcasting in North America. 85KHz was also used as a "second-IF" in dual-conversion receivers intended for professional/amateur 'communications' service, it's easier to get good selectivity at a lower IF. |
3rd Mar 2018, 12:12 am | #5 |
Dekatron
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Location: Gateshead, Tyne and Wear, UK.
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Re: When & where was the first Superhet produced?
The concept of the superheterodyne radio receiver dates back to the early part of the 20th century. http://ethw.org/Superheterodyne_Receiver
A few superhet receivers were on sale during the 1920s. Mass produced superhets were on sale in 1933. Examples are the HMV 440 and Marconi 272. https://www.radiomuseum.org/r/marconi_272.html DFWB. |