[Elecraft] K3 - FSK question

[nr4c at widomaker.com]

Hi, I'm new to the K3, (Aug 2010 sn 4536). I have really enjoyed it a  
lot. I have dabbled into digital modes a bit and am wondering, how do  
i connect and send/rec FSK?

I have determined that I need a cable from PC serial port to the  
"accessory" connector and connect to gnd, PTT, and FSK. Do I still use  
the soundcard to rec or does the radio have a line out that would  
connect to the serial port RX pin?

Another question. Last night I was messing with PSK, and noticed that  
in PSKD mode, the waterfall on Digipan showed a band of activity at  
one area of the display, while in DATA A mode, it had shifted a lot to  
the left, maybe 1khz. What gives?

...bc nr4c