The “Tape” output of the D100/D200/D230/240x bat detector has a two-channel (stereo) jack. In order to use a mono recorder, you need a special “stereo-to-mono” cable that connects the channel from which you want to record to a mono (2-pole) plug that fits in the recorder.
The D940/980 uses “phono” jacks on the Tape output, hence a mono cable is all it takes to connect it to a mono recorder.
If you have a stereo recorder, you should use a two-channel (stereo) cable. The D500X and D1000X have built-in recorders so there is no need to connect an external recorder.