Yaesu FT-90 Programming Cable – DIY Instructions – Make it yourself!

I recently purchased an Yaesu FT-90 to play around with. It came with a mic with the typical cracking, falling apart cable. Luckily replacement cables are available readily on auction sites and Amazon- so this was a quick swap to make it all work and look like new. Next question was programming.

The FT-90 is supported by CHIRP, but I needed a cable. While the FT-90 can be programmed manually, I’ve compiled a list of local repeaters on other radios and wanted to just import it. However, the unit did not come with a programming cable. I looked around and could find a suitable cable — but it was $35 bucks. The radio was under $100 and mic cable $8, so I didn’t want to put 1/3 more into this radio just to play around with it. Instead I searched and found VR2XKP’s site which described adapting a schematic from a rs232 circuit for use with a cheap Prolific USB to serial.

I was lucky enough to have an Prolific cable in my parts drawer from a previous project constructing a packet radio, and have many other basic components on hand. The only item I needed to find to construct a programming cable was the RJ12 cable. While it looks a standard telephone cable, pins 2 and 4 are used, so I opted for a flat cable 6P6C to make sure all pins were active. This cost about 5 bucks shipped on Amazon.

Parts Needed

6ft RJ12 cable

Prolific or FTDI USB-to-Serial cable (note that if you are having trouble with current Windows properly recognizing your older, potentially, ‘not authentic’ cable you will need to find and install older drivers- they will work fine with Windows 11 in my experience.)

10k resistor

1N4148 diode

solder

glue (optional)

heat shrink (optional)

Assembly

1. Solder diode between RX and TX with cathode to TX.
2. Solder resistor between VDD(VCC) and RX.
3. Solder wire that connects to pin 4 (on mic jack) to GND and pin 2 (on mic jack) to the RX.

Mic Pinout Diagram (looking at jack on transceiver):

   6 5 4 3 2 1
______________
[    |  |  |  |  |  |   ]   
[____       _____]
        [___]        

You may choose to use heat shrink to keep components from shorting and/or add glue to hold wires in place. I was able to fit all components and the flat cable into the original cable plastic housing.