[Hallicrafters] SX101A 50.75KC IF Amplifier

[Mark K3MSB]

If one looks at the schematics for the SX-101A, specifically the rear
wafer (S5A Front) for the Selectivity switch, I notice that the
Hallicrafters engineers switch in a 470 ohm resistor (R31) for the 1
KHz selectivity setting only.    This adds an addition 470 ohms to
cathode and grid of V6, for the 1 KHz setting only.

I'm curious as to why they do this for just the 1 KHz setting only,
and none of the others.

Mark K3MSB