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Digimodes and a FT747GX........

Discussion in 'Working Different Modes' started by MI0OIM, Aug 20, 2013.

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  1. MI0OIM

    MI0OIM Ham Member QRZ Page

    I NEED AN ELMER!!!!!!

    Ok folks I'm totally new to digimodes.

    I have a DIGI M8 interface from MCR, which has a built in USB soundcard.

    the rig is a FT747GX

    form googling, I see that the only way to connect up is using the mic plug on the front of the rig for an input, output can be the AF out, round the back and as there's no VOX in a 747GX I need to manually do that.

    so, there is a PTT line on the interface. do I need to switch that manually in parallel to the rig (DPDT switch?) and the controls are TX gain, RX gain & delay. tghe first two I understand, but what needs delayed?


  2. K0RGR

    K0RGR Premium Subscriber QRZ Page

    I don't have any information on the Digi M8 interface. But on the FT747GX, all the connections are available for use with a typical digital interface. I will assume for a moment that the M* works like most of the others out there.

    PTT should be controlled by a virtual serial port through the USB connection to the M8. The PTT output from the M8 should be connected to the PTT jack on the rear panel of the 747 with an RCA plug. The computer software you use will be looking for a serial port number to use for PTT. Assuming you are using Windows, you will have to go into the Control Panel - Hardware and Sound - Devices and Printers - Device Manager. The listing will show a category for 'Ports'. If the M8 is connected and everything is working, you should see a 'port' number associated with it. You may need to unplug and replug the M8 to identify which port it is. Once you've set this port number in the digital software, it should be able to key the radio when you go into transmit.

    There is also an AF Output RCA jack on the back of the radio. This should go to the audio input on the M8 - it provides a constant level audio output so the AF gain control doesn't affect it. This way, you can turn the audio on the radio down or off, and still be able to do digi modes - a very nice feature.

    The 747 does not have a separate input for the transmit audio, so you will have to obtain a mike connector and wire it to feed the audio from the M8/computer into the mic input. I think the M8 has a separate level control for the transmit audio, so you can set it for proper operation with the mic gain set at it's normal level for SSB.
  3. MI0OIM

    MI0OIM Ham Member QRZ Page


    thanks a lot, REALLY appreciated!

    NOW my problem now is......

    what wire is where?

    the construction instructions with the interface kit are OK, but they leave out THIS info.......

    In the diagram below the connector on the right has 4 wires, but it doesn't say which is which or what goes where.....

    I can see that the top one is rig earth
    next is audio from rig to interface
    and the bottom two must be signal out to the rig? what's the difference?

    so going with what K0RGR so kindly said, the PTT line goes to the jack on the rear of the rig,

    wires 1&2 go to an RCA AF out on the rig, and these other two..... the mic plug, but where?

    and is it OK to run a line into the mic plug and keep the original mic attached or should I switch back & forward?



    Last edited: Aug 21, 2013
  4. K0RGR

    K0RGR Premium Subscriber QRZ Page

    The mic audio would go to the center pin 8 on the mic connector, and the shield would go to the ground pin. You can't tell from the diagram which side of the socket it is depicting so you will need to measure from the two pins on either side of the 'notch' pin to see which side is grounded, which will be pin 7. I think I'd use a separate plug. What you're suggesting with adding to the current one might work, but you could also damage your sensitive mic with audio out from the soundcard, and it could introduce other problems.

    I think you should contact the seller of the interface if more assistance is needed.
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