IC-746 - data TX at 144Mhz

Discussion in 'VHF/UHF - 50Mhz and Beyond' started by MW1CFN, Oct 3, 2019.

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  1. MW1CFN

    MW1CFN Ham Member QRZ Page

    I've just acquired an IC-746, which I am having difficulty sending data with, but only at 144MHz.

    I can't see any obvious settings problems. Any advice welcome!

  2. KC3RN

    KC3RN Ham Member QRZ Page

    What interface are you using? What acc port on the rig? I use port 1 and a SignaLink with mine. Port 1 doesn't recognize the PTT signal on 2m, so I need to switch the rig into transmit manually.... Also, the 746 doesn't mute the mic input, so be sure to turn the mic gain down on the front of the rig.
  3. MW1CFN

    MW1CFN Ham Member QRZ Page

    Thanks very much. I had a kind reply from ICOM themselves today. The interface in use isn't really relevant as it turns out, but it's a ZLP DataLink.

    ICOM tell me that 2m PTT is triggered by the VSEND pin (6) on ACC2. One can toggle HSEND and VSEND for HF and VHF operation, or they can be tied together as far as I understand. I'm not yet clear as to the best way to connect things up, so if you or others have any ideas, happy to hear about them!

  4. MW1CFN

    MW1CFN Ham Member QRZ Page

    KC3RN likes this.
  5. DM2TT

    DM2TT Ham Member QRZ Page

    I used these radios,incl. ic275,475, 7400,and now 970 with a homemade vox box that triggers ptt once the computer throws out audio.
    Extremly simple but works OK.
    But there is one big problem with the IC746/7400:They drift a lot on 144MHz!
    So you might consider the (expensive) icom crystal oven or built something yourself.
    Not exactly a rig made for digi modes on 144MHz!
  6. DM2TT

    DM2TT Ham Member QRZ Page

    I use the ACC plug on the back for straight audio in and out to the computers soundcard.No problem!
  7. N2SLO

    N2SLO XML Subscriber QRZ Page

    CR282 you can still find them like $150.. I wouldn't call that expensive to stop drift. I have a 746 that drifts, but with other radios that have digital capability, not worth it to add it.

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