Modifications for the Kenwood VFO-120



09-04-2000 VFO-120 Dial Lamp Switching Circuit
Author: Trio-Kenwood Communication, inc.


Service Bulletin no. 862 (14-4-1982)

When operated with a TS-130 series transceiver, the dial lamp on the external VFO will remain on if the power supply remains on, ever through the transceiver is off. Adding a transistor switch on the VFO-120 switch unit X41-1240-00 will provide automatic lamp operation from the transceiver power switch.

On the Switch unit, add transistor Q1 2SC1959(Y) (V03-1959-06) as a pilot light ground switch, controlled by the transceiver 9V DC line. Connect Q1 emitter to ground, collector to the pilot light ground (either the lead, or connector CJ-2, pin 2) and base through a 4.7 Kohm resistor (R9) (RD14CB2E472J) to the 9V line.

Note:

  1. This change may be applied to units before serial number 110001.
  2. Installation time for this procedure is ½ hour or less.