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

[Leslie Smith]

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
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/arc5/attachments/20230107/93e2aabb/attachment.html>