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DM 780 locks up on RTTY

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  • DM 780 locks up on RTTY

    I read all I could find on the subject. I have an FT450D, signallink USB, running Win 10. I am able to decode RTTY, but when I try and transmit, the rig keys for less than a second then drops and the DM780 program freezes and must be restarted. I previously (a year ago) used fldigi without an issue. I reduced power to 5 watts after a suggestion in the FAQ about rf into the computer, with no change. Any other suggestions? Thanks Mike

  • #2
    I think you are on the right track.
    It can be hard to track down RFI.

    Get some snap on 31 mix ferrite chokes wind several turns on the cores.
    Wind everything that connects to your computer.
    Mouse,keyboard,usb cables that run to rig,if you use sdr radio then that usb also.
    And the 120v line too..I can get 6 turns on a 3/4'' snap on core.
    I also run a ground wire to the computer (the case) you may have to jumper to the different sections in the PC.

    Also it helps to have resonant antennas.
    This is a good link that will help with RFI. http://audiosystemsgroup.com/publish.htm
    Good common mode chokes can be made from 4'' cores and RG400 install at the feed of your antenna..will handle 1500w.

    Google this guy too ...he has a good power point slides ...Ward Silver N0AX Grounding and bonding

    Anyway good luck finding the problem...Like I said you are on the right track..

    73 Fred KB4QZH


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    • #3
      Thanks Fred. For some reason, I thyink I have a port issue...a port dropping. I am going to try SSTV, FT8 and Fldigi to see if the problem persists. In reality, I don't us rtty. I am just trying to set it up, become familiar with it so I can help a fellow ham.....learning

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      • #4
        If you have a port drop out issue that is almost certainly caused by rfi.
        Open Device Manager to the Com Ports list and watch them as you transmit.
        That will tell you if it is rfi or not.
        Icom ic-7610, SPE 1K-FA amp,Hex beam, Butternut HF6V and homebrew 40m/60m/80m trap dipole.
        PC - Windows 10.
        Intel 4 Core i5-4460 CPU@3.2GHz, 8GB RAM,

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        • #5
          I am waiting for a supply of ferrites. One additional piece of information, I reduced power to 5 watts and still had the program freeze. I have yet to try fldigi to see if it is an HRD computer issue. Thanks

          Comment


          • #6
            Originally posted by MadMike View Post
            I am waiting for a supply of ferrites. One additional piece of information, I reduced power to 5 watts and still had the program freeze. I have yet to try fldigi to see if it is an HRD computer issue. Thanks
            What aerial are you using? What is the feeder?
            Icom ic-7610, SPE 1K-FA amp,Hex beam, Butternut HF6V and homebrew 40m/60m/80m trap dipole.
            PC - Windows 10.
            Intel 4 Core i5-4460 CPU@3.2GHz, 8GB RAM,

            Comment


            • #7
              I'm not familiar with the FT450D but, are you trying to run AFSK or FSK? If AFSK then, can you transmit other digital modes using DM 780? If you can, that would tend to say it is not an RFI problem.
              73,
              Charlie, KØLAF

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              • #8
                FSK, not AFSK. Will try psk31 or jt65. Just seems intersinter that fldigi works normally in FSK. If other modes don't work is it a port issue? Or RF issue. Still need to watch device mgr as suggested. Wish I we're more computer savvy.

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                • #9
                  Intersinter means inconsistent. ???

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                  • #10
                    Well, I tried PSK31 and JT65. They both run just fine. Then I tried AFSK and it too ran fine. Now I need to better understand the difference between the two of those modes. Anyone with an answer?

                    Comment


                    • #11
                      http://www.hfradio.org.uk/html/digital_modes.html
                      Icom ic-7610, SPE 1K-FA amp,Hex beam, Butternut HF6V and homebrew 40m/60m/80m trap dipole.
                      PC - Windows 10.
                      Intel 4 Core i5-4460 CPU@3.2GHz, 8GB RAM,

                      Comment


                      • #12
                        Originally posted by MadMike View Post
                        Well, I tried PSK31 and JT65. They both run just fine. Then I tried AFSK and it too ran fine. Now I need to better understand the difference between the two of those modes. Anyone with an answer?
                        In PSK31, JT65, and AFSK modes, DM-780 is using the signalink soundcard to send audio tones to the FT450D which is operating in USB mode. The signalink has a built in VOX circuit which acts as a PTT to put the transceiver into transmit mode.

                        When you use FSK mode in DM-780 you have to have your FT450D in FSK mode also. The FT450D has an input that has to be toggled which causes the transmitter to generate the FSK signal. In this mode you will need to have DM-780 configured to use HRD or RTS/DTR or some external hardware to act as the PTT signal. Additionally, you would need DM-780 to toggle the FSK input of the transceiver to cause it to generate the FSK signal.

                        From a transmitted signal standpoint, there is vertually no difference between AFSK and FSK. However most rigs have additional filtering in FSK mode which is why some people prefer its use.

                        So, I suspect the problem here is that you have an incomplete setup and configuration to use FSK.

                        73, Charlie, K0LAF

                        PS., How about giving us your name and callsign?
                        73,
                        Charlie, KØLAF

                        Comment


                        • #13
                          Thanks Charlie. Makes some sense and since I would very rarely use rtty, I'll just ues AFSK and try to get used to this mode. I need to change my forum name to my call sign. Thanks, Mike Davis WA1MAD

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