Mixer design - comments please

[Alex Crow <acrow@xxxxxxxxxxxxxxxxxxxx]

Hi All,

With the help of some very good chaps on this list I am now comitted to 
working on a General Coverage receiver to work with Linrad in the I/Q mode, 
to receive SSB and AM, both amateur and broadcast. My design is based largely 
on the SDR-1000 articles, and I have just finished the design of what should 
be the Tayloe Detector part.

I have replaced the (too expensive) Instrumentation amps with a cascade of 
NE5534's, and have (tentatively) reworked for a single +5V supply. What I 
would like is for you chaps to have a look at my circuit and make any 
criticisms and reccomendations you see fit: I only have enough resources at 
the moment to make one board for each part and would like them to work first 
time! BTW, I am using Eagle for the CAD of these bits.

If you feel I should give the Op-Amps a 10V supply please tell me, and if you 
can explain why the input bias to the Tayloe detector in the SDR-1000 seems 
to be 1V, when the Instr. Amps have the whole 10V to play with!

The url for the schematic  is:
http://home.clara.net/alexcrow/mixer.png

I can also put the Eagle files up there if anyone is interested.

BTW, I know I need some electolytics on the ouput to the soundcard!

Thanks  muchly in advance,

Alex



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