Low cost and home made equiptment is a key driver here at PI4CC.

RTTY is nice mode to operate. With a K3 and divisity RX it will be nice to have 2 RTTY decoders at low cost. With 2 MTTY decoders and the 2 receivers build in the K3 we can read rtty transmisions at once.
Next step is to "foul" Win-test. Win-test can handle just one decoder per radio. With LP-brigde we make 2 virtual ports and make Win-test thinks that there are 2 radio's. connected. Those 2 radio's get the same CAT control so there are in sync with each other. Actually we use the K3 in diversity config.

To make PTT and CW keyer via RS232 possbile, just divided the RS232 port FROM the K3 in 2 com ports. Split them to group CAT with ground (5), RXD (2), TXD (3) and group CW/PTT with ground (5), DTR (4) and RTS (7). The CAT port is connected to the virtual com port splitter. Group CW/PTT is not in use while running RTTY, but needed when running SSB/CW.

FSK is done via 2 opto couplers build in a backshell RS232 connector. Build two times the interface and pallalel the feed to the K3 AUX connector.
Have a look at the pictures below.

Install MTTY in a sub directory MAIN. Make a second sub directory SUB Install MTTY in both and configure them as above. You need to copy the EXTFSK.dll into the MTTY directories.

GL!