There have been instances in the Model 16, Code 125 and 126 where a parasitic oscillation occurs in the receiver. This condition, which is caused by a slightly unstable circuit, can be corrected by placing a 70 ohm carbon resistor [not the newer film or wire-wound types], part No. 33-1129, in the plate circuit of the 78 RF tube. The wires on the plate terminal of the tube socket are removed, and the resistor is insereted in series. The condenser, shown in the digram as No. 2-A, Service Bulletin No. 205, is removed from the circuit.
From the Philco Serviceman – September, 1935.