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).