I want to use a straight key. So the way I figure it, I can use a tone generator (http://www.morsex.com/misc/ttone.htm) sent into either a USB mic converter (http://www.antonline.com/p_ICUSBAUDIOB-NX_531075.htm) or into the analog line input on the computer's sound board.
Occasionally, I must use a code practice oscillator instead of Dahdidah to send code on QSONET.
My kit includes the MFJ 554 ($90) Sine Wave Output Classroom Code Practice Oscillator, a Vibroplex Standard Original Bug, a Vibroplex Deluxe Straight Key and two cables. One cable has a 1/4 inch mono audio plug that goes to the key input of the CPO. The other end of that cable has 2 gator clips to connect to the keys.
The second cable is a length of RG-58 (it's what I had laying around) with an 1/8 inch mono plug on one end and a 1/8 stereo plug on the other. I opened the cable in the middle and wired a .1 microfarad low voltage cap in series with the center conductor for isolation and crude impedance matching. It works very well. Nice clean tone and no clicks, pops or buzzes.
I adjust the pitch to my liking on the CPO. The volume knob sets the level on the CQ100 transceiver. I monitor my transmit audio in the computer so I can hear what I'm sending.
The CQ100 is set for VOX operation mode with sensitivity set at 8 and Dwell set at 1 second. Works great!!!
It's not as nice as running Dahdidah but it works well and allows me to enjoy the CW experience on QSONET.