[FADCA] Would this work for HIGH speed?

[Chuck Hast]

On Fri, 25 Feb 2005 03:34:49 -0500, Bill Sinbine <n4xeo at bellsouth.net> wrote:
> Do you think this might be a option to get some high speed links going with
> the Motorola radios?
> If they have the proper frequency on the if this might be a option and
> would let us get above 19200 baud. This would come out less than the Tait
> radios are and would go much faster.
> Does someone know if these would work in the radios we are using now?
> 
> I'm looking at putting one in my ft-847 for sat work and this is how I got
> the thought.
> 
> Just a snip from the web site listed below.
> 
> Amateur-satellites with 38400 Baud FSK-modulation (G3RUH) are in the orbit
> since 1999. First packet-radio digipeaters with 76 kBaud are operative in
> Germany. With the IFD, you can expand the capabilities of most amateur
> radio receivers to high speed data reception as 38400, 76800 and up to
> 153600 Baud.
> 
> Principle of function: The IF signal of your amateur radio receiver is
> tapped directly behind the rf frontend (1st mixer) and connected to the
> input of the IFD module. There, the signal is converted to a second IF
> frequency of  10,7 MHz by a mixer circuit and a fixed frequency crystal
> oscillator. The IFD assembly is available for most common IF frequencies
> e.g. 71 MHz, 45 MHz, 21,4 MHz, 13,45 MHz or 47,43 MHz (FT736) or 10,7 MHz.
> The bandwidth of the IFD amplifier is standard 110 kHz for 76 kBit/s
> maximum data rate. Wider filters (300 kHz / 156 kBaud) or narrower types
> (80 kHz / 38 kBaud) are available upon request.
> 
> http://www.symek.com/g/ifd.html
> 
> 180.00 EUR
> Euro   =   237.535 USD
> United States Dollars
> 1 EUR = 1.31964 USD 1 USD = 0.757785 EUR
> 

What about the TX side. This is interesting. It deals with the If filter issues
on the RX side, but many radios have BW limiting in the TX stages and
when you jumper it out you get into other issues. But the idea looks good.



-- 
Chuck Hast 
To paraphrase my flight instructor;
"the only dumb question is the one you DID NOT ask resulting in my going
out and having to identify your bits and pieces in the midst of torn
and twisted metal."