[R-390] Product detectors for dummies

[Ing. Giovanni Becattini]

1) why do we say that our R-390A has not a product detector? If I correctly understood, when we use the BFO, we practically use a product detector. I would prefer to say that we can implement a better product detector. Is this correct?
2) The use of BFO as is, produces a local carrier which is too low in relation to the IF out which contains the side band. For this, we need to attenuate the RF gain to get a good audio signal. Is this correct?
3) my 51J-4 seems to work much better than the R-390A receiving SSB signals. This is partly confirmed by the fact that Collins officially sold 51J-4 ALSO for SSB. Looking at the schematic, I could not find an explanation for that; the signal from the BFO is simply connected to the envelope rectifier diode. Was it simply designed “better”?

Forgive this donkey… 😁