What audio connector is on the Minifon P55 recorder?

Just bagged a Minifon P55 wire recorder, and while I know it will take a bit of work and engineering to get it going, I am looking forward to doing so. Although, one thing I haven't been able to identify yet is what kind of connector the audio goes though. (It's the one on the right in the picture.) I have noticed, though, that there are some that has a plain, Jane 1/4 phono connector, although I would rather build a dongle to plug into the one installed for now.