Yaesu FT-757GXII Software and CAT info


Development of the software on this page has been discontinued.
Source code now available further down.

About the Yaesu FT-757GXII Cat interface

The cat interface on the FT-757 is a standard Mini-DIN 6 pin (PS2-style) connector with TTL levels.
An RS232 converter like the MAX232 or similar (I use MAX233) can be used to interface a computer.
Adding a simple opto coupler to this to control the PTT also found in this jack and a 78L05 to supply the power from the 8V or 13.5V RCA jacks makes this a complete cat interface.
People often use darlington opto-couplers but the 4n35 will probably work just fine.

ONE IMPORTANT THING: If you have problems getting data through from the tranciever to the computer you might have to add a pull-down resistor to the TTL serial output of the cat connector. About 2K will do. Apparently the 757 does not have any external or internal pull-down resistors on this output.
The problem can apparently be found on other older Yaesu rigs as well.

Yaesu FT-757GXII Control Software for Windows

I have bodged together a simple control software for the FT-757GXII. It is freeware and source code is available
on request. It was made using Visual Basic 2005 Express and requires .NET 2.0.

Features include:
Mode and frequency setting
Split mode toggle
Clarifier mode toggle
Gen/ham step toggle
Dial lock toggle
VFO A/B selection
Band Up/Down buttons
Memory Up/Down when in Memory Mode
Status polling of all these values and TX status
Switching between VFO and memory mode – Thanks to Robert, N2JTX.
Bugs are included at no extra cost.

Download: Updated EXE 2009-09-07 v1.1.0.0
Download: Installation package v1.0.0.6
Download: Old EXE file v1.0.0.6

Download Source Code: ft757gxiicontroller-src

18 Replies to “Yaesu FT-757GXII Software and CAT info”

  1. Dear Robert,
    I would like to adapt your software on my old FT767GXII to enable the Cross-Frequency VFO function.
    Wowld you be so kind to send me the source code to my Email?
    Thank you in advance and ’73 de IZ4FXC op. Greg.

  2. Hi Robert,
    I recently got a Yaesu FT-757GXII and am interested to program the CAT interface. I am a professional .NET programmer so I’m very interested in the source code of the Visual Basic application you wrote to control the FT-757.
    Could I get a copy of that please?
    73 de Cees

  3. quick question you refer to adding pullup resistors I am planing to use optocouplers for the serial connection do the pullup resisors need to be on the radio side tor the PC side?


    1. Hi Yonu,

      This rig has a floating nature of the TTL rx and tx so on the radio side I had to put pulldowns (or pull-ups, if you have a sink design) on my rs232 converter. I had a max3232 to do that job and I didn’t use opto coupling on rx and tx, only on ptt.
      Good luck

  4. Thanks that is what I need to know I think 🙂 I am using optocouplers as I want complete isolation between the pc and radio I am even using them on the audio. now I just have to figure this out with optoisolators lol.


  5. I’m working on getting a CAT interface working for the X1M transceiver and thought looking at your source code would help speed up the process. I’d appreciate it!


  6. Looking at the features of the FT-757GX CAT system it does not seem to offer the feature of reading out the frequency of the transceiver. Am I correct is this assumption?


    Larry DL8VKO

    1. I am fairly sure that is correct. The CAT commands of the Mark I and II are very similar, but commands 12-16 are missing in Mark I.
      Also, the 757GX Mark I only has CAT input (TTL RX), so it can only be controlled from an external device.
      The 757GX Mark II has both input and output, and frequency can be read back with command 16 (10h “READ STATUS”).

  7. Hi friend.

    Can you send me the code please?
    I will try to adapt to Ft-747

    My email is (address removed)

    Thanks a lot.

  8. I too am interested in adapting the source to to my Yaesu FT-100
    Could I get a copy of the source code? Thanks
    Lloyd – WA9NLA

    1. The 757GX Cat reference is available in the official service manual. The 757GXII has this information included in the user manual. (also see email 🙂 )

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