ITT Marine STR 12
The STR12, an older marine VHF from ITT Marine, can be modified quite easily with a discriminator output for the reception of AIS.
ITT Marine STR-12
The receiver IC, an SL660C, can be found on the left side of the circuit board. To reach the IC, the outside and inside covers have to be removed. The unfiltered audio can be found on pin 8 of the SL660.
SL660 - pin 8 carries the unfiltered audio
The components used
Follow the next steps to make the discriminator output:
The connections to the IC and ground
The 3.5 mm chassis socket
The chassis socket can be mounted in the cover plate of the unused right input. Use some hot glue to fix the cover plate.
Photos and text: Henk van Rooijen