thanks for the replies..
The MX-12 works on Relfex how it should. Further i checked outgoing voltage on the jack output. My 7C puts out 2,75 volts, the MX12 1,1 volts.
So i tried amplifing the signal and that did the trick. Phoenix now read the transmitter, but i know it's not the way it suppose to work.
And profile in Phoenix itself does not matter. I tried all of the JR types.
I'm going to try on a different PC in a while, but if anyone has another idea just shout out!