[HomeBrew] Direct conversion receiver

[Steven Weber]

>
> The receive module is based on the MRX-40 DC receiver as seen in CQ and 
> other places:
>   http://www.w5usj.com/images/surfacemount/mrx40-smt-schem%20v3.pdf
>
I find the 612/386 combo to be a bit on the weak side, even with the extra 
gain cap on the 386. It would pay to add a differental input gain stage 
after the 612, maybe a gain of 20. Use a dual op amp and add an audio band 
pass filter contered on 600 Hz for better selectivity. Finally add a volume 
control between the new op amp stage(s) and the 386, as now you'll need it.

Not knowing what kind of filters and how they are connected on the front 
end, there maybe some losses there too.

Steve KD1JV