[Dx4win] DX4WIN CW/PTT Interface LPT1 port

[kea_company]

As wrote in DX4 manual
pin 1 - strobe
pin16 - PTT
pin17 - CW
The emitter of both transistors to pin 1
Collector of each transistors to PTT and CWKey of Radio.
But where is ground? To connect Radio need another line:
two wire to PTT (from collector and ground)
two wire to CWKey (from collector and ground).
Pin 1 to ground?
In N6TR the ground was pin 18 - all other is same
Sorry for stupid question & poor English.
Vlad UA6JD
ua6jd@qsl.net