Yaesu FT-736R CAT problem

Discussion in 'General Technical Questions and Answers' started by W4DWR, Jun 23, 2010.

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  1. W4DWR

    W4DWR Ham Member QRZ Page

    Just purchased a FT-736R and I love it, except for 2 problems, the CAT comes on by itself, and occassionally the radio will key up automatically.
    when the radio is on for a good length of time I will notice the CAT indicator is lit and I have no control of any functions except TX & RX on the frequency it's on. When the radio is in memory scan it doesn't seem to happen, but I can't be sure.
    I am wondering if there is a program in the CAT calling it on. I have done a master reset, before that the AQS would come on by itself, but that hasn't happened since...How can I see if the CAT is on or off.......David W4DWR
  2. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    I know one thing

    ...about this.

    Don't let the CAT circuit get wet.

    In fact, the photo shows the proper arrangement.
  3. W4DWR

    W4DWR Ham Member QRZ Page

    Thank you

    Over 29,000 posts, all the same picture or do you try to be helpfull at times :)
  4. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    I've never posted that picture before.

    I have an FT-736R myself and have never had this problem; however I've also never used the CAT interface so I'm not even sure if it works!

    There are some Yaesu reflectors where real Yaesu specialists hang out, you might inquire there and see if anyone's run across this. Yaesu Service might have a suggestion also, although I don't know if they still service this rig (mine's from 1987).
  5. W4DWR

    W4DWR Ham Member QRZ Page

    THank you

    I'll google yaesu reflectors and see if I can get some help, thank you
  6. N9ATV

    N9ATV Ham Member QRZ Page


    Do you have anything connected to the CAT interface on the back of the radio? I have owned my 736 since 1996 and never had mine come on by itself. When I start the program I use to control the radio, the interface activates but when the program is closed the interface shuts off.

    If you have anything connected to the CAT interface remove it and see if you still have the problem. If the problem clears up build or buy another interface and try that.

    If nothing is connected, your CAT should not engage and there is nothing built into the radio calling it to come on. If it is there may be something wrong with the radio. The CAT circuit should never activate by itself at any time especially if you have nothing connected to the CAT port.

    Good Luck!
  7. W4DWR

    W4DWR Ham Member QRZ Page


    I have nothing connected to the back of the radio, when I first received the radio the AQS would come on and key up the radio after it was turned on for awhile usually over an hour. I did a master reset and that seems to have stopped. I noticed yesterday, the cat indicator came on and I just let it go because I was using the radio on that frequency anyway, after about 30 minutes it went off and was okay after that until I shut down for the night. Can I disconnect that board if need be, but not sure which one it is....May I ask what program you use to control the radio, I would like to get it if it is pretty easy to install and use. I'm retired and although I am very resourceful, I am still in the learning stage with computers, and don't know anyone that could give me advice.
    I really appreciate the time you have taken to help me out, I love the radio and hopefully will be able to get into satellite work and utilize the capabilities of the unit....David W4DWR
  8. W4DWR

    W4DWR Ham Member QRZ Page


    Any info you could supply as far computer program, what interface or best way to connect to the radio, or any info that you have learned about the radio would be greatly appreciated......Thanks again......David
  9. N9ATV

    N9ATV Ham Member QRZ Page

    Sorry but it sounds like you may have something wrong with the radio but someone else may have had this problem and can chime in on what you can do.

    I don't think you can "cut" the CAT curcuit from the radio since it is most likely hardwired to the processor and you never know what might happen so I wouldn't suggest that. You may want to open it up and see if anyone did a MOD on the radio that may be causing the trouble. It is a long shot but you never know.

    For software control I use several different programs but this may be the easiest to use.


    The cable I use to connect the radio to the serial port on the computer is home made using a MAX232 chip to change the serial output to TTL for the radio to accept. Here is a link to another cable but I haven't used this one before but looks like it may work but I suggest to use the MAX232 chip.


    If you get a MAX232 chip look near the top of this page for the schematic. This is what I use and never gave me any problems and is still working today.


    Feel free to contact me at the email that is listed on my QRZ listing if you like. I will do what I can to help you out.
  10. N5AL

    N5AL Premium Subscriber QRZ Page

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