Cable for Yaesu FT-900

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Audio signals in FT-900 can be found on 3.5mm TRS socket:

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Serial CAT control lines and PTT can be found on 6 pin MiniDin socket:

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The pinout cable for Digirig should be as follows:

3.5mm tip (DATA IN) → audio 3.5mm TRRS ring1 (RIG_AFIN)
3.5mm ring (DATA OUT) → audio 3.5mm TRRS tip (RIG_AFOUT)
3.5mm sleeve (GND) → audio 3.5mm TRRS sleeve (GND)

MiniDin6 pin 1 (GND) → serial 3.5mm TRRS sleeve (GND)
MiniDin6 pin 2 (SERIAL OUT) → serial 3.5mm TRRS ring 1 (RIG_TXD)
MiniDin6 pin 3 (SERIAL IN) → serial 3.5mm TRRS tip (RIG_RXD)
MiniDin6 pin 4 (PTT) → audio 3.5mm TRRS ring 2 (PTT)

From what I’m gathering from online sources, the serial port uses logic levels.

The link to the manuals can be found on this page.

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I worked on a friend’s DigiRig setup today with this radio (FT-900). I will post my findings and modification necessary to get it working. I can confirm that the radio uses TTL level control on the serial connection.

I used flrig software to confirm serial port functionality of the radio with the modifications and cables I made.

The software is available here.

http://www.w1hkj.com/

My friend’s station is now up on WinLink using Vara HF and a DigiRig. He is very happy on this rainy day in his ham shack.

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So there are no commercial ready made cables for the FT-900. Hams have always been tinkering making their own setups. I will say buying a ready made cable is slick and easy. You too can make your own cable.

I did cheat a little bit. I did not make the entire cable from scratch. I like the DigiRig quality of cables so I purchased a set of Xiegu G90 cables to cut up.

The reason I chose the Xiegu G90 cables is because I have one and I already knew the pinouts would work.

The FT-900 radio uses a old school PS-2 connector type for the serial connector. It has Ground, TX data, RX data, and PTT in that connector ready to go. The Audio path for the FT-900 uses a 3.5mm stereo plug which has Ground, and Mic, and Speaker audio.

The DigiRig has the Audio path setup with PTT which is awesome, but I want clean cables. So we have to make sure the 3.3v jumper pad on the Digirig is not soldered. By default it was not. I then needed to jumper the PTT internally on the DigiRig from the Audio side to the Serial side. (See drawings below).

The 3.3v Jumper Pad is highlighted in RED circle.

PTT (Ring 2) and 3.3v (Ring 2) jumpers boxed out in BLUE.

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Here is where the actual jumper goes on the bottom of the DigiRig (Blue highlights)

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So I took the Xiegu G-90 cable and cut off the PS-2 style connector right where it enters the connector.

The wire colors were the default colors that the Xiegu G90 cable I had used.

I wired it up as this.

T - DigiRig TXD. (Red wire)

R1 - DigiRig RXD (White wire)

R2 - PTT (jumper int) (Green wire)

S - GND (Black wire)

FT-900 (PS-2 plug)

Pin 1 - GND. (Black wire)

Pin 2 - Serial Out (White wire)

Pin 3 - Serial In (Red wire)

Pin 4 - PTT (Green wire)

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With this cable made it will work with fldigi and WinLink setup.

Flrig software list a FT-900 for use. WinLink with Vara HF setup has no FT-900 to use. I used a FT-920 in the settings and it worked great.

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Only settings on your setup that will vary should be the Com port. On this computer it was Com 9, but yours may vary.

I will post the Audio cable in another reply.

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Here is the Audio cord pinout from the DigiRig to the FT-900.

I used the Xiegu G-90 serial cable 3.5mm TSSR to 3.5 mm TSR one. This would be used as a Serial cable on the G-90, but for this I will cut off the TSR 90 deg stereo connector and put a new 3.5mm TSR connector on.

Here are the pinouts once you put the new connector on.

DigiRig Audio

T - DigiRig Mic In

R1 - DigiRig SPKR Out

R2 - PTT (jumper int on DigiRig) not used in this Audio cable

S - GND

FT-900 (3.5mm plug)

T - Audio In (goes to R1 - DigiRig SPKR Out)

R - Audio Out (goes to T - DigiRig Mic In)

S - GND to GND

Here is the drawing of how to wire up the new Audio 3.5mm TSR stero jack on the FT-900. (Note The Xiegu G-90 serial cable is not wired correctly for us to use it directly for this cable. Hence the new 3.5mm TSR stereo connector.) I did cheat a little bit like I said using partial made cables with ferrite beads from DigiRig. I just repurposed them to work for this setup for my friend’s FT-900 rig).

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I can’t say enough nice things on how sleek and easy the DigiRig is. One USB-C connector to your PC that does Audio paths, Serial data if needed, and PTT.

I’ve used them all. Rigblaster, SignaLink, and others. Hands down the smallest , simplest, and cheapest is DigiRig.

https://www.tigertronics.com/slusbmain.htm

I hope this helps. If anyone has any questions feel free to reply back here.

Here is a copy of the manual for those looking to do something with the FT-900.

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I have tried to make the cables as described above. So far I haven’t succeeded with the serial MiniDin6 cable, but still work on it. The audio cable with one modification has worked for me. I connected the 3.5mm TRRS audio ring2 (PTT) with a separate wire and a phonoplug/RCA plug to the PTT jack. This works for me, (but of course it doesn’t control the frequency). See also “Cable for Yaesu FT-890 and FT-900”