I´m using the Yaesu FT-8800 with the Byonics TinyTrak4 as APRS tracker in my car. There is a menu setting to bind the data jack to a VFO, but transmission is always done using main VFO. So if I talk to someone using the second VFO, the modem will send its beacon to the voice QRG.

Since a few days I´m working on a modification to the rig, but I want to be sure this is really needed. My modification will intercept the communication between the main CPU and the panel CPU and supress the data transmission while in QSO... Its open source - if you are interested have a look at http://github.com/thosch1800/FT8800mod

Question: Does someone know a way around (without any modification)? I wonder if I´m the only one who owns this setup and is not comfortable with it...

EDIT: I want to be able to use my radio like a normal radio - grab the mic and start talking - plus the APRS via TT4. In my opinion it has many benefits: You need only one antenna, only one device, your able to use it like a 'normal' radio.


1 Answer 1


I believe you may have misinterpreted the menu setting. You can select the packet receiving band (main, right, left) but the packet transmitting band is fixed on the main band.

The TinyTrak4 has a PTT input connection for the purpose of suppressing data transmissions when the transmitter is in use for other purposes. This would seem to be a good fit for your use case. To take advantage of this feature, simply route your microphone PTT line to this input. When the TT4 sees this input is grounded (via the microphone PTT), it will suppress transmissions.

If you are concerned about the TT4 interrupting a QSO when you are not transmitting but listening to the other station, you could add a delay timer (e.g. 555) to the PTT input to the TT4. Setting the timer for 4 or 5 minutes would hold of any TT4 transmissions during the course of most QSOs.

  • $\begingroup$ This is the point. I want to modify the FT-8800 to suppress the data transmission during QSO. And I dont want to switch between the VFOs anymore. The voice band stays activated at any time. When TT4 sets PTT the FT will change VFO, transmit and change back to voice. $\endgroup$ Sep 13, 2017 at 20:11
  • $\begingroup$ So why not use the TT4 PTT input for this purpose? $\endgroup$
    – Glenn W9IQ
    Sep 13, 2017 at 20:31
  • $\begingroup$ Because I still would have to change the VFO manually. Your sulution would suppress the APRS transmit. I want a smart system - APRS operation as long as the radio is not in use for voice transmissions and voice operation without bothering with VFO changes. I´m not feeling comfortable with the way yaesu wants me to use such a system. I wonder why no one else want such a feature. I think with the (more expensive) Kenwood radios (designed for APRS) you would not have to change the VFO before starting a voice QSO. $\endgroup$ Sep 14, 2017 at 6:22
  • $\begingroup$ Which signal would you use for the TT4 PTT input? Doesn´t it require a modification as well? I´ve searched for 0/5V signals on the main PCB where I could infer the active VFO - but no luck. $\endgroup$ Sep 14, 2017 at 7:37
  • 1
    $\begingroup$ Yes, it will almost always involve compromises. Good luck with the project. $\endgroup$
    – Glenn W9IQ
    Sep 14, 2017 at 8:03

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