well for a matter of fact you do not need one if you run FLDIGI or HRD/DM780 it will talk the FLEX 6500 just fine. Here is the web site to download the drivers for FLDIGI http://www.w1hkj.com/download.html you will see flex below. and of course HRD cost but it works good with my FLEX 6500 and win 7. hope this was helpful
PS for JT65 I use HRD as a connection to the and run JT65 thru HRD, it works just fine.
DAX seems to have about a 6 dB gain advantage over external digital interfaces... You lose about 3dB intelligence when converting from Analog to Digital and another 3dB of intelligence converting back to digital again inside the Signalink
Simple non scientific numbers with JT65 on the same antenna at the same time.
Best Decode with a Signalink and an IC-7700 was -19dB
Flex 6700 using internal DAX - 26dB
1st off your not alone. When I tried psk in the beginning I couldn't get DM780 to key my radio.
Working on DM780 with the HRD support staff then finally the owner of the company. It looked like the error was with the Flex software.
Dudley and I still couldn't solve it he is Flex tech support. Then one day out of the nowhere it worked. My problem was not DAX but PTT settings.
Hang in there because the final result is so well interfaced.
Now at 100+ PSK contacts I enjoy digital communications more then SSB.