[ARC5] The Regenerative Superhet - Armstrong meets Armstrong.

[Leslie Smith]

           The regenerative (or Jones) superhet.

In a previous topic (Edwin Armstrong and the superhet) Hue Miller wrote:
"The regenerative detector in the superhet receiver was something only the
Germans and Japanese used, and even there it was not usual."

In the years before WWII Frank Jones published a number of articles about a
set he called Super-Gainer.  His designs show a 6K8 in front of a regen
detector operating at a fixed I.F. - often 1600 or 1750kHz.  In later ARRL
handbooks this appeared as the band-imaging superhet.

David Newkirk published some informative pages on this topic here:
 http://dpnwritings.nfshost.com/ej/goodman_receiver/

This leads to an early set used by the Polish underground - the Pipszhtok.
On YouTube:  https://www.youtube.com/watch?v=CsL7ekFLPGs

Another snippet of information is here:
https://www.warrelics.eu/forum/equipment-field-gear/polish-spy-radio-85602/

This was, so far as my limited knowledge goes, a Jones superhet running a
6k8 into a 6J7 (or maybe a 6K7) detector at 1500/1600kHz.  That closes the
loop to the point made by Hue, viz the "regenerative detector in a
superhet" used in Germany and Japan.  Except this was Poland and the
underground.  I have never seen a circuit of this set.  I would be most
interested to see one.  The Pipszhtok may also be known as the A1 or Nelka;
I'm uncertain on that point.

I always admired the underground operators; they were, it seems,
extra-ordinarily brave.  Please, do not take my remark 'extra-ordinarily
brave' to detract from the courage of non-wireless operators except:  Every
time these fellows closed the key a signal went out that said, "Over here,
Gestapo, look over here."  And so (as I understand it) about one in four
Polish operators were caught by one means or another.

The idea of a receiver radiating a locating signal applies particularly to
the Paraset radio.  Even when receiving (at least when searching for CW
from England) these radiated a "locating signal" of some milliwatts
directly to the aerial.  Recently I built a small transistorised regen
receiver.  I was astonished when I tuned my set to the frequency of the
local 10kW broadcast station - 1512kHz.  The signal from my set into the
aerial (6V DC at 3mA) "buried" the BC station on a nearby radio!   Wow!
How far up and down the street was my signal killing reception on 1512?
How soon before the district radio inspector's van arrived at my front
door?  I disconnected the 6V supply from my little 3-transistor wonder,
turned off the house-lights and went to bed.   I pulled the blanket over my
head.  There I was safe, I knew, from the dreaded RI.

Despite this tendency to radiate, I always admired the very practical
design of the Paraset.  It was functional, simple but also offered the best
chance of being repaired by the underground.  The Pipszhtok added one
additional 'toob' (6K8) to reduce radiation a good deal and provide better
selectivity than was available in the Paraset.  Clever fellow the Polish
types.  Gave us a lead into Enigma and (after that) Reverse Polish
Notation.

Thus Armstrong's superhet took about 12 to 15 years to appear in commercial
and military use.  (We may think that Drake intended his "K" series for the
aviation industry initially - I don't know about that.  In a very short
time the Jones superhet was replaced by the full superhet.  It was always a
curiosity.  The SCR-274 by the A.R.C was, I guess, the model for the AA5 -
but that's certainly speculation on my part.

At any rate, if anyone here has a circuit for the Pipszhtok or Nelka A1,
please write.

73 from VK where it is summer.

Leslie
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