[ARC5] How Edwin Armstrong invented the superhet (according to Wikipedia)

[Tom Lee]

I'd be very interested in hearing what others have to say on this topic. 
I serve on the board of the Armstrong Memorial Research Foundation 
(established by Armstrong's widow, Marion), so you might imagine that I 
have a certain point of view on the subject.

-- Happy New Year to all,
Tom

-- 
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
420 Via Palou Mall
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu

On 1/6/2023 23:21, Leslie Smith wrote:
> Hello All:
>
> When the Aircraft Radio Corporation built the superhets we call 
> SCR-274 (or ARC-5) it was all because the British Admiralty felt the 
> high cost of RDF (etc) was justified. Read all about it below.
>
> From Wikipedia: https://en.wikipedia.org/wiki/Superheterodyne_receiver#RDF
>
> "*RDF*
> /There was one role where the regenerative system was not suitable, 
> even for Morse code sources, and that was the task of radio direction 
> finding, or RDF."
>
> "The regenerative system was highly non-linear, amplifying any signal 
> above a certain threshold by a huge amount, sometimes so large it 
> caused it to turn into a transmitter (which was the entire concept 
> behind IFF). In RDF, the strength of the signal is used to determine 
> the location of the transmitter, so one requires linear amplification 
> to allow the strength of the original signal, often very weak, to be 
> accurately measured."
>
> "To address this need, RDF systems of the era used triodes operating 
> below unity. To get a usable signal from such a system, tens or even 
> hundreds of triodes had to be used, connected together anode-to-grid. 
> These amplifiers drew enormous amounts of power and required a team of 
> maintenance engineers to keep them running. Nevertheless, the 
> strategic value of direction finding on weak signals was so high that 
> the British Admiralty felt the high cost was justified."/
>
> I found the above when hunting for a little history of the development 
> of the superhet.  My first reaction was to send it to "our" resident 
> historian (Hue).  I admire his extensive knowledge of radio history 
> and enjoy reading his postings here.  Then I thought others may find 
> the role of the British Admiralty "interesting" and so I sent it here 
> instead.
>
> I must seek information about the development of the superhet 
> elsewhere, it seems.
>
> Best 2023 to all
>
> Leslie
>
>
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