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Make a Modified "CT-69" for other Yaesu Radios.
By Brian, MW0GKX
With additional content by Phil, W4AIN.

Because this project uses a modular plug you may require the use of specialised crimping pliers.

My thanks go to Phil Parrish, W4AIN, for the heads up on the fact that Yeasu mics don't have a "common" pin configuration, this page has now been updated to cater for this.


This adaptor allows the use of 8 Pin round Yaesu microphones on some Yaesu radios with the 6P6C modular socket. The image below shows the view of the 6P6C plug with the locking tab underneath and wire connectors toward you. The 8 Pin round "socket" (actually the male, or plug but referred to as socket) is viewed looking into it as if you were about to put a plug in it.

I suggest building this in a small project box as there are some resistors that need fitting for the functions to work, if you only require the PTT function you may be able to fit the required resistor (R1) inside a line plug but the design shown here also allows for the Up/Down on the microphone to work as well.


6P6C modular plug.
8 pin round socket (locking ring type).
R1: 27kΩ ¼W.
R2: 66kΩ ¼W.
R3 148kΩ ¼W.
Small project box.
3 core cable to suit.
Some short lengths of hook up wire may be required.


connection diagram1 Strip off a small amount of the outer sheath of the cable and, making a note of the order of the colours, crimp the modular plug onto the cable.
NOTE: only pins 1, 2 and 3 are used. (You may find it easier to line up the wires if you carefully press pins 4 to 6 in with a screwdriver on the bench first).

2 Drill holes in the box for the cable and the chassis socket and mount the chassis socket to the box.

3 Cut the cable to the required length (if not already) and insert it into the hole drilled for it (you may wish to use a grommet) and tie a knot in the cable for strain relief.

4 Strip some of the sheath from the free end of the cable and strip and tin the free ends of the wires ready to connect the chassis socket and resistors.5 Using the notes made in step 1 and referring to the diagram, solder the wires to the correct pins on the chassis socket. Modular pin 2 goes straight to pin 8 on the chassis socket and modular pin 3 goes to both pin 2 and pin 7 (or pin 5 and pin 7, see note above) on the chassis socket.

connection diagram6 Connect (using some hook up wire if needed) R1 to pin 6 on the chassis socket and the wire from pin 1 of the modular plug.

7 Connect (using some hook up wire if needed) R2 to pin 3 on the chassis socket and the wire from pin 1 of the modular plug.

8 Connect (using some hook up wire if needed) R3 to pin 1 on the chassis socket and the wire from pin 1 of the modular plug.

9 Check that nothing can short out (use some tape or sleeving if required) and close the box.

Compatible Radios

This adaptor will work with: FT-90, FT-100D, FT-2600, FT-3000, FT-7100, FT-8000 and FT-8100 and other radios that use the MH-36B6JS or MH-42B6J / MH-42B6JS microphone.

Other Yaesu 6 pin Modular Mic Socket Radios

For an adaptor to fit the FT-1500, FT-1802, FT-2800, FT-7800 (Dual Band with Modular Socket), FT-8800, FT-8900 see the Yaesu CT-69 Adaptor page.

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