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How can I get a relay closure, or TTL ground

How can I get a relay closure, or TTL ground when I press Tune button to activate my TuneMatic screwdriver antenna controller. I have a 6400M. If I can get this signal, I can remote my setup better at an HOA.


  • KD0RC
    KD0RC Member, Super Elmer Moderator

    Hi Jonathan, the TX1, TX2 and TX3 outputs go to ground when you press Tune, MOX or PTT. Use the TX Band Settings screen to set up the PTT output that you want to use on each band.

    If setting the output needs to be done only when the Tune button is pressed, you would need a companion program that would set the output accordingly.

    Another approach is to have a small microcontroller output a low when the Tune button is pressed. It could have its own button(s) for Tune or any other functions that you might want. Check out my QRZ page to see what I have done in this area (TeensyMaestro).

    My current (so far successful) experimentation involves a $6 Raspberry Pi pico W. It finds and connects to my WiFi, then finds and connects to my Flex 6400. It currently uses an optical encoder to tune VFO A, a mechanical encoder to change volume on slice A, and it displays the frequency on a small tft color display.

    If you are interested in something like this, let me know - I would love to help. It would be cheap and easy to implement.

  • KD0RC
    KD0RC Member, Super Elmer Moderator

    Another thought crossed my mind... There are cheap ($20 ish) WiFi switches that can be accessed remotely from a cell phone. I use a 4 channel model to remotely power on my 6400 and switch among 3 antennas. One of the outputs could be used to put your antenna controller into tune mode.

  • rdwing
    rdwing Member ✭✭

    Perhaps use two different TX profiles. One for pulling say RCA TX2 to ground only, when you assert TUN. Then switch back to main profile to assert RCA TX1 for keying your amp.

  • David Decoons, wo2x
    David Decoons, wo2x Member, Super Elmer Moderator

    You can do this pretty easy with a Raspberry Pi running Node Red and an inexpensive relay hat board for the Pi. I modified my Node Red flow today to prove it out and it works fine.

    If you want to go down the Node Red rabbit hole, let me know.


    Dave wo2x

  • K1DBO
    K1DBO Member ✭✭✭

    Yet another rabbit hole is the increasingly poorly named 'Broadcast' feature in Slice Master. Currently there are two options for controlling bits of a USB bit cable plugged directly into the radio. The existing options are centered around dropping the key line to an amp when tuning a KAT-500 or HF-Auto for "one touch tuning".

    A USB Bit Cable with relays already installed can be had from Amazon in either a 4 or 8 relay version for under $30 (https://www.amazon.com/gp/product/B009A524Z0). No third party software is needed to control these boards. Their use is limited only by the configuration options already available in SSDR.

    As others have pointed out, third party software and/or additional hardware give even more flexibility.

    Now with all that said, a quick read of TuneMatic's web site suggests that simply using the TX1, TX2, or TX3 connectors on the back of you radio is likely all you need.


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