Frede,
No rush. It's just always exciting when something like this turns up.
I would think that a decoder like the one mounted in my Grand Prix 609 would
be the one to fit.
The Dirigent 610K service manual mentions a complete MPX module as part
number 900 H 198
I have checked this up against the one in the Grand Prix but
that one only has the number 602 L 24 stamped on the backside.
I seem to remember that it is running on 200V DC so it could very well
fit in the Minette (and others).
The Dirigent 609K service manual mentions the FM stereo test broadcasts that
could be received by connecting f.e. a Beolit portable radio to the Dirigent, thereby
letting them receive each their channel using the stereo amplifier in the Dirigent to amplify
the signal from both but that's about all MPX info found in there.
The Minette 609K service manual shows three points for connecting the MPX decoder
(just before the output) but neither of the above manuals give any documentation
on the module itself.
The Grandprix 610 service manual mentions the Decoder 610 with a Noval socket
but refers to a separate manual for that module (which I am quite sure that I don't have).
However, it does give the connections to the Grand Prix circuit and also shows 6,3V AC
going to the MPX module so I suppose that would have been valve based or at least
prepared for it.
I have some Dirigent 609/610 sets in my collection that I never opened and also
some Grand Prix and Master Deluxe models from that time so maybe - just maybe -
one of them will contain a module. (I can dream, can't I).
I think, I will try to document the decoder mounted in the Grand Prix and maybe
also figure out how - and where it is connected.
Martin