Drake R-4C - Receiver - Noise Blanker Alignment

Always Turn off your Drake R-4C Receiver before Plugging in or unplugging the Drake 4-NB Noise Blanker Module.

Connect a VTVM between the chassis and R45.
Tune the Drake R-4C to 28.5MHz while using the crystal calibrator as a signal source.
With the function switchin the CAL position , adjust C3 and C6 for the maximum S-Meter reading.
With the function switchin the NB Position and the RF Gain set fully CCW, adjust R28 for a maximum positive voltage on R45.
Connected a Jumper from Pin 2 of the Calibrator Socket (Brown/White Wire) to Ground.
Adjust the RF Gain Control to maintain 10 Volts on R45 while adjusting C19 and C25 for maximum positive voltage of R45.
Remove the Jumper from Pin 2 and return the RF Gain control to fully CW.
With the Calibrator turned on, adjust R12 so that the S-Meter has the same reading with the Drake 4-NB installed as it does with it removed and the jumperplug installed.

Thanks to Gary, (W8PU) and the Zerobeat Website for the information.

Last Updated : 30th August 2024

Drake R-4C – Receiver – Noise Blanker Alignment