I am considering buying a Byonics TinyTraK4 to connect to my Kenwood TM-281a to do APRS.

However, I am wondering if I should instead buy a separate radio (I am considering a Baofeng UV-5R) as well and connect the TT4 to it instead of the TM-281A.

My fear is that with the TT4 connected to the TM-281, I will no longer be able to use the it for other communications unless I disconnect the TT4.

Is it possible to use the Kenwood for normal communications even while the TT4 is connected to it?

  • $\begingroup$ The TT is for transmit only. How do you plan to use it for APRS? On the specific APRS channel, or on a repeater channel, with a repeater that mutes and forwards packets? I remember with the TT2 it could be used as a kind of "over bleep", then you could keep both Mic and TT plugged in and working. $\endgroup$
    – tomnexus
    Jan 5, 2015 at 10:49
  • $\begingroup$ @tomnexus I am planning to use it on the 144.39 MHZ APRS frequency but want to be able to use the TM-281A for normal 2-meter repeater work as well. $\endgroup$
    – W8AWT
    Jan 5, 2015 at 18:27
  • $\begingroup$ Hmm, tricky. But another radio is such a lot of wiring, another antenna, urgh! Perhaps you could add something to the TT to adjust the radio's frequency through its serial port, transmit, and change it back. Advanced PIC hacking though. Perhaps if the TM-281 has a Priority channel, you could simulate the button-press quite easily. Still, tricky. $\endgroup$
    – tomnexus
    Jan 5, 2015 at 20:00

1 Answer 1


No, this would not be possible unless you were to program a PIC chip to switch the radio to the call channel, which would be set to the 144.930 MHZ APRS frquency when it heard an APRS brap from the TT. It would then have to switch the radio back when the APRS had been sent. Still, It would be VERY tricky because the PIC would only be switching the radio when it heard the APRS, not before. So, unless you could have the TT start transmitting but wait one second to send the APRS so the PIC could switch the TT, it would not work.

Additionally, how could the TT know when you were keying the mike?


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