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Shipmate RS 8100

Airspy 007

It's not too difficult to make the marine VHF Shipmate RS 8100 suited for the recepton of AIS by adding a discriminator output.

The receiver IC is located at the bottom of the circuit board. To reach the bottom, 9 metal screws and one plastic screw need to be removed. After that, the board can be carefully lifted from the enclosure.

The baseband audio can be found on pin 9 of the MC3361.

Shipmate RS 8100
Top view
Location of the MC3361
10 screws need to be removed
Pin 9 of the MC3361 contains the unfiltered audio

Follow the next steps to make the discriminator output:

  • Connect a 10 k resistor to pin 9 of the MC3361
  • Connect a 2.2 nF capacitor from the resistor's other lead to ground, e.g. to the solder pad shown on the photo below.
  • Connect the inner conductor of a piece of shielded wire to the junction of the resistor and capacitor
  • Connect the braid to the solder pad
Because the enclosure is rather robust, which makes drilling difficult, you can choose not to put a chassis socket in the enclosure, but to put a female (cinch) connector to the shielded wire outside the RS8100 ('pigtail', see top photo).
Connection to the IC
Shielded cable detail
Close-up of the connection to the IC
Shielded wire, leading to the outside world

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