Hallicrafters SR-150 Operation And Maintenance Manual page 28

(see drawing below). There is one thing to check before considering this approach. Some K1 relays do not have
that contact. The contacts are stacked. So if you have a junk box full of relays and can find a similar relay, you
can add the needed contact. You will need to add a 750 to 800 ohm resistor from the cathode of V13 to ground
to compensate for the coil resistance of K3.
By Walter Cates WD0GOF (UPDATE 10/30/2013) 28