Shipmate RS 8300
It's not too difficult to make the marine VHF Shipmate RS 8300 suited for the reception of
AIS by adding a discriminator output.
The baseband audio can be found on pin 9 of the MC3361.
Shipmate RS 8300
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 (GND on the picture below)
- Connect a 10 uF, 16 V electrolytic capacitor with its plus lead to the junction of the resistor and capacitor
- Connect the inner conductor of a piece of shielded wire to the minus lead of the 10 uF capacitor
- Connect the braid to ground
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 (3.5 mm mono)
connector to the shielded wire outside the RS8300 ('pigtail', see top photo).
Pin 9 of the MC3361 contains the unfiltered audio
Close-up of the connection to the IC
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