[amsat-bb] Re: C Band Downconverter

Andrew T. Flowers, K0SM aflowers at frontiernet.net
Fri Sep 15 10:21:28 PDT 2006

I think someone mentioned the idea of using the S-band RX converter as 
an intermediate IF.  I was playing around with the idea of using an MMDS 
converter with a C-band mixer.  If you can move the LO in the MMDS 
converter up to 2700 MHz, that gives you a 3130 MHz IF for 5830.  If you 
then use the MMDS converter's guts for the second conversion (you may 
have to tweak a filter or two to pass the 3130), you will get 430 MHz IF 
received.  In other words, you can use the MMDS converter's LO for both 
first *and* second IF. 

Granted getting those things to oscillate at 2.7 GHz is a ways from 
where they were designed.  Still, it might be a fun project....and you 
get to do a little algebra.  It may be easier just to get an old PLL 
brick, preamp, filter and mixer.  RX or TX converters aren't too hard to 
build since you can generally avoid complexities for TR switching.

-Andy K0SM/2

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