[ARC5] How Edwin Armstrong invented the superhet

[William Cromwell]

Hi,

A TRF receiver processes an incoming signal at the frequency of that 
signal all the way to whatever detector is used. Not necessarily a 
regenerative detector. The Michigan Traffic Net (QMN) for example is at 
3.563 mc. A TRF receiver processes that signal at 3.563 mc all the way 
to the detector. It could be an infinite impedance detector, a diode 
detector, a regenerative detector. a product detector,  and thereafter 
the signal is audio.

My regen receivers have at least one rf amp ahead of the detector to 
isolate the antenna from the detector. So they are TRF receivers with 
regen detctors. Simpler receivers have the detector as the first stage 
so there is no TRF processing. Could be a regen or a diode detector.

Superheterodyne receivers convert the incoming signal to some 
intermediate frequency (or perhaps two or three) and most of the 
processing occurs at that fixed frequency and that is followed by the 
detector (could be a regen detector). Superhets have many advantages 
over TRF receivers as well as some serious problems all their own. I am 
working on a superhet with a regenerative detector - just for fun. ARRL 
publications have two similar designs two use as a pattern.

73,

Bill  KU8H

bark less - wag more

On 1/7/23 07:37, 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
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