FT-991 - Dual CAT port operation

Discussion in 'Radio Circuits, Repair & Performance' started by PY2RAF, Sep 3, 2019.

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  1. PY2RAF

    PY2RAF XML Subscriber QRZ Page

    Hi there, QRZers.

    In my quest abusing investigating my FT-991A functionalities, I found something very interesting.

    As of now, I thought that you would control the FT-991/A using either the Serial port (the DB9 connector at the radio rear) or make use of the USB port that seamlessly exports the CAT interface to your computer via the USB port.

    So, I thought it was a either selection: You would control the radio by either the USB or RS-232 ports.

    Well, after doing some tests with the serial port I just went curious and connected both USB and Serial to the computer. It is not a OR, but a... AND!

    To my amazement, the radio was happily controlled via both interfaces at the same time. And the noteworthy news is, when you send a command through a CAT interface, this command is not echoed on the other interface, which is great, the radio providing separation of both interfaces.

    So, if you have a FT-991A and have to resort to hacks such as Virtual Serial Port Splitters, etc., well, you can definitely use both interfaces, at the same time. Just change the menu 028 - GPS/232 Select to 'RS232C', set the proper baud rate and connect it to your computer serial port. If you don't have a serial port (which is the case on modern computers), just get a USB-to-serial converter, hook it to the DB-25 port in the radio and the USB port in your computer.

    Choose the USB port in one app, the Serial port in other app and let them both take advantage of CAT. At the same time.

    Hope that helps, 73,

    - Rodrigo.
    Last edited: Sep 3, 2019
    YT4EW likes this.
  2. K3DDT

    K3DDT XML Subscriber QRZ Page


    It seems appropriate to respond to this post here. This discovery is going to save me quite a bit of time. I was about to explore ways to enable PTT through the 6 pin DIN RTTY/DATA port. I never considered that both interfaces would be active at the same time.

    PY2RAF likes this.

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