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Thursday, January 12, 2017

N6ORS's Franken-SDR Superhet


Of course, I love it.  MOSFETS!  NE602's!  10.7 Mc IF cans!  Cycles, not hertz! And a Tayloe Quadrature Sampling Detector made from junkbox parts from the Reagan administration. FB Keith.   And the frequency display is icing on the cake.  

Bill:

I thought the group might find my new Franken-SDR interesting.
It is an SDR with a superhet front end. 


I wanted to play with an SDR but I didn't want to get a kit or buy
parts, so I scrounged through he drawers and found a mux chip
cd-4016 circa-1980 some old 7400 logic that is probably per-1980.
This could make a QSD but only very low frequencies. Well I thought
how about at IF frequencies?


The frontend is a MOSFET mixer (1975) , the 10.7 IF is a dual gate MOSFET
(1975), the second mixer is a NE602, the IF cans are all stagger tuned to
give a bandwidth of 50kcs.
The only thing modern is the DDS but I old-time-ifyed it with BCD switches.


Keith N6ORS





VK6FTH did something similar: http://www.vk6fh.com/vk6fh/SDRradio.htm


2 comments:

  1. Bill, thanks for the link to franks site,
    enjoyable reading and lots of fun ideas.
    73, Keith N6ORS

    ReplyDelete
  2. I love the old thumb-wheel switches and the variants that had push buttons (top button incremented up and the bottom button incremented down) and the lever switches.

    ReplyDelete

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