I have added an "optional" i.f. regeneration component (C15) to my 1941 Single-Signal receiver.http://www.bignick.net/images/RadioPix/7_tube/schematic_7_tube.jpghttp://www.bignick.net/Morgan_Radio/Radio_6.htm
It provides a degree of regeneration in the i.f. stage, sharpening response.
The handbook tells me to re-align the i.f. stage after the installation of the feedback capacitor (C15), which I did. The i.f. peaking adjustment was much more touchy than it had been when aligning the i.f. without the feedback component.
Now, when I advance the r.f. gain, the audio will squeal if adjusted too high, which is expected because the i.f. stage breaks into oscillation. The optimum r.f. gain setting is just prior to the i.f. stage breaking into oscillation according to the handbook.
The receiver sounds differently than it did without the feedback component, as expected. The sharper i.f. has a narrower band pass and hence less background noise.
The whole idea of adding the i.f. regeneration is to allow the operator to be able to tune to a CW signal on just one side of zero-beat instead of on both sides, as is the common case.
The problem is that I still cannot seem to achieve the single-signal reception that the sharper i.f. tuning is supposed to provide.
For that matter, I cannot locate any theory of circuit operation that explains why this sharpened regenerative response will create single-signal reception.
Does anyone have experience with this circuit/methodology or could point me to a reference?
The ARRL handbook talks about phasing of crystal filters in the i.f. which makes sense, but I do not see why a sharp regenerative i.f. peak could provide single-signal reception?