Some of the packing shows SEM 52 even though there is a SEM 52-A inside. Also, Jane's mentions several other versions of the SEM 52 with more channels or different frequency bands. If anyone has seen a nameplate showing a straight SEM-52 without the A, please let me know. There is an easier way, so now I have to get some of the male connectors that interface to the H-250 handset. Anyway, the following info is about the SEM 52 audio connector.
Progression is clockwise from the top of the unit connector.
Be careful your colours may vary. Mark and I have one wire a different colour. SEM 52 Headset wiring diagram. The surprise is two wires for the ear piece. There has to be an ohmic connection between yellow and white or the audio goes away.