[ARC5] How Edwin Armstrong invented the superhet

[Michael Hanz]

On 1/7/2023 7:37 AM, releazer at earthlink.net wrote:
> I had always assumed that;
>
> 1.  The TRF set is essentially a Superhet IF.
> 2.  The TRF has some major disadvantages for multiband sets, like the big clunky coils of my RU receiver
> 3.  The TRF had to cost more to build than the Superhet, given that complex tuning mechanism.
> 4.  Hence the Superhet.
>
> Now, since they used CW a great deal in those thrilling days of yesteryear, how did they receive it on a TRF set?
>
> Wayne
> WB5WSV

I don't track non-aircraft developments much, but there were two methods 
I've seen, one developed by Aircraft Radio Corporation for the Navy sets 
and another by the Signal Corps.

The ARC design introduced a circuit called the audio heterodyne 
oscillator, described in this simple? explanation below:






The second method was the RC-12 oscillator/detector, described in these 
two files on my website:

https://aafradio.org/docs/Oscillator_Equipment_RC-12_(BC-RC-183).pdf
https://aafradio.org/garajmahal/BC-RC-183_Mount.html

The SCR-183/283 sets didn't have an audio heterodyne oscillator like the 
Navy sets, so the Signal Corps did the next best thing - made a separate 
box to do the job in larger aircraft.  It wasn't so great in a single 
seat fighter...



73,
Mike  KC4TOS
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