Modifications for the Kenwood MC-46



19-07-1998 MC-46 DTMF Mic. With older equipment

The MC-46 DTMF (Dual Tone Multi Frequency, or Touchtone (TM)) microphone may be adapted for operation with any VHF or UHF radio by changing the supplied six pin mic connector to a five pin, four pin, or other connector, as required. Radios not originally supplied with regulated, filtered B+ at the mic connector need also to be modified to power the microphone.

The MC-46 standard six pin mic connector is part no E07-0651-05, and is wired:
     Pin 1 White    Mic Output
         2 Red      PTT
         3 Blue     Down
         4 Green    Up
         5 Brown    B+ (8.5 VDC +/- 10%)
         6 Shield
The Four pin connector part no is E07-0403-05. Radios built with a four pin jack do not supply B+ to operate the mic, and must be modified to deliver a constant source of DC to operate the mic and DTMF keyboard. Any Kenwood product of this vintage will have a B+ line designated "C9" (Common 9V DC), wich is regulated, filtered, and noise-free. Rewire the mic as described below:
     Pin 1 White    Mic Output
         2 Red      PTT
         3 Shield   Common Ground
         4 Brown    C9
Rewire the radio mic jack: pin 3 to common ground, pin 4 to C9.

Rewire the stock mic for pin 3 common ground. Otherwise, the mic element will be returned to C9, instead of ground. Note this change on the radio schematic.

The Five pin connector part no. is E07--551-05. Radios built with a 5 pin jack supply correct B+ for a DTMF mic (originally designated MC-45, and no longer available). Wire the mic as described below:
     Pin 1 White    Mic Output
         2 Red      PTT
         3 Brown    B+
         4,5 Shield Common Ground
Mating chassis connectors are:
     Four Pin       E06-0403-05
     Five Pin       E06-0552-05
     Six Pin        E06-651-05