The discriminator output contains a rather strong 455 kHz component. By connecting the 10 k resistor to a grounded capacor, a simple lowpass filter is created. I used a capacitor of 2.2 nF, resulting in a cutoff frequency of about 7 kHz. The IF component is surpressed effectively this way. The capacitor is connected to the metal shield of the IF coil, which is grounded.

A 3.5 mm chassis terminal is mounted in the left bottom part of the back panel. This terminal is connected to the capacitor and ground.