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Discussion in 'Working Different Modes' started by KC3QZN, Oct 17, 2021.

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  1. KC3QZN

    KC3QZN Ham Member QRZ Page

    I am trying to explore FLDIGI using a TM-D710GA. I have the PG-5H cable kit but I'm confused about the connections for it. One of the cables is intended to connect the RX/TX unit of the radio to the PC's sound card. The other cable is shown to connect the RX/TX unit to a serial port on the PC - according to the printed manual that came with the radio. What is confusing is that the manual on the CD that came with the radio says (under the PACKET communication section) "The COM terminal is on the rear of the OPERATION PANEL. Connect this terminal to a personal computer: do not connect a computer to the PC terminal of the TX/RX unit. BTW - because none of my laptops has as serial port, I have a USB - Serial adapter (FT232R USB UART). I have successfully used the MCP-6A program to upload / download programming from the radio WHILE CONNECTED TO THE PC PORT ON THE BACK OF THE RX/TX UNIT. So, my questions are: a) Which is the proper connection point for the data (PC) cable to the radio when doing digital mode comms - the port on the back of the display (operation panel) - or is it to the port on the RX/TX unit? b) If the radio has a built-in Terminal Node Controller - why are the audio signal cables even needed. Wouldn't the TNC allow the radio to communicate to the PC via DATA signal? c) I noticed while experimenting with the FLDIGI program that I am seeing data stream on the incoming data window, and activity on the waterfall - even when there is NO possible source?! I have seen this when the radio is completely disconnected from the PC. I even disabled my network connection. How is this possible? Complete newb to this digital comm thing and will welcome any help I can get.
    Last edited: Oct 17, 2021
  2. N1ZZZ

    N1ZZZ Ham Member QRZ Page

    I run FLDigi via a Signalink to my TM-D710. I'll try to break it down for you.

    The COM socket on the Operational Panel is to get get data from the radio's built in TNC to a computer. This is a very simple TNC and has limited capabilities. This outputs binary data from the TNC and can't be used for soundcard modes.

    The DATA port on the RX/TX unit is the one I use most. This is the port you use to get audio to and from a soundcard interface for use by FLDigi. You need to use an external soundcard interface (I use a signalink) to get the proper audio levels between the radio and computer, and also allows for a PTT circuit. This is the port to use for programs like FLDigi, MMSSTV, and soundcard packet programs.

    The PC port is used for programming the radio and not much else.

    The next issue is setting the "data" VFO. I used VFO "B". To use the soundcard interface plugged into the DATA port, I turn off the internal TNC (neither APRS nor PACKET are in the display). The interface will not key the VFO that isn't set for "data." It also won't key if the internal TNC is on. However, the audio can be monitored by the computer program simultaneously along with the internal TNC. I often monitor APRS display on the D710 and the RAW packets on the computer.

    For question "b" the TNC is only used for AFSK packet. If you want to use FLDigi's other modes or even SSTV etc you need to use an external interface from the DATA port into a computer. The internal TNC outputs serial data while the DATA port allows audio frequencies to go in and out of the radio. Soundcard modes operate on audio sounds not binary data.

    The answer to "c" is line noise and happens all the time and is nothing to be worried about.

    I use my radio mostly to monitor local APRS using the internal TNC. I also send SSTV and use FLDigi for moving forms. I have also used it with soundcard packet and VARA when I use it with Winlink. I don't use the internal TNC for vanilla packet, only for APRS.

    I hope this helps. If you have any other questions, feel free to ask.

    Jeremy N1ZZZ

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