Tim Wescott ) writes:

I've seen designs in old handbooks that used regeneration in the RF stage
to sharpen up the response there -- that would, indeed, help the image
rejection at the expense of intermodulation performance.

That was a weird period, because it seemed to only exist after there
were single conversion receivers with IFs in the HF range, and then
disappeared somewhat later.

Indeed, it seemed to all be tracked to a receiver using a 7360 as
the mixer, and I can't remember whether the Q-multiplier was in
that famous article in QST by Squires circa 1963 (and if so, it
would have been in that famous Squires-Sanders receiver of the same
period), or if the construction article in QST that seemed based
on the Squires article introduced it.

So for almost the next decade, others would put that front end
q-multiplier in their single conversion receivers with the 7360
mixer (and there was even a mosfet based version).

The secondary articles were clearly doing it because the first
article did.

But I've always wondered about the first article. Since yes,
the receiver used a tuned circuit into a mixer, so the receiver
did lack front end selectivity. But, the mixer was about the
best for the time, and the IF was in the HF range. So it was
far less likely to overload than many mixers of the period, and
image rejection was easy with the high IF.

Later, the notion of high IFs became more common, and nobody
particularly worried about image rejection, even though they
too were using single tuned circuits into the mixer.

So did Goodman toss in the front end Q-multiplier because
of a perceived or real need for extra front end selectivity?
Or did he simply want to play with the concept?

What never made sense was that he went for the front end
q-multiplier with it's added tube and added ability to overload,
when any other receiver would have simply added better front
end selectivity.

Michael VE2BVW