Hello Jara and Steven,It is a great pleasure for me to inform that finally the EM83 MW receiver
worked with controlled regeneration happily and efficiently.
Only needed to change the 390k anode resistor of the left hand triode to
1.2M ohms, in order to low down quiescent plate current, which in turn was
giving too much voltage gain. Regens need very litttle plate (anode) current
for controlled regeneration to be effective. Now I use conventional L-C
feedback network from plate to ground, as in Armstrong receiver.
The RF choke needed some medium-value resistance in parallel in order to
damp oscillations when the regeneration control capacitor was fully unmeshed
(vanes opened) at the low frequency end of the band. I used a 62k ohms
resistor I had at hand. My choke is 3.3mH pile wound.
I get great sensitivity. Selectivity is superb. The "eyes" work OK,
especially the right "eye", which indicates relative amplitudes of
demodulated signal. The left eye reacts very litttle.
The power supply measured 140V DC. The 1.2M ohm resistor has a voltage drop
of 120V, giving an anode (plate) current of 100uA.
Filament supply reads 4V rms on my DMM.
I am using ferrite antenna with no external antenna.
Best regards,
Ramon