The Sony Air-7 is a vintage receiver. Thanks to the spacious layout, it's not to difficult to equip it with a discriminator output.
This receiver uses a discriminator circuit with discrete components: a ceramic filter and two diodes. The unfiltered audio can be found on the cathode of diode D23.
The linearity of this discriminator circuit is poor and therefore less suited for AIS. However, the Air-7 performs well as a paging receiver.
The cathode of D23 contains the unfiltered audio
The right pin of D23 is the cathode
Use the next steps to make a discriminator output:
The components for the discriminator output
These two wires need to be connected
The earphone socket can be reused.
Overview of the discriminator output