I have a YT-100 connected to my FT-857d in my remote-by-default shack in the attic (i.e. I operate it over a VNC connection from elsewhere in my house). Whenever I change band I have to go up to the attic to press the button to re-tune the ATU. It's an easy enough process as it finds the match itself, however it's a bit of a pain to do.

Question is, if I just start transmitting without re-tuning, will the ATU detect the mismatch and trigger a re-tune on its own?

Follow-up question (if it doesn't re-tune itself) - is anyone aware of an interface between the remote jack on the rear of the ATU and a PC to simulate pushing the tune button?


1 Answer 1


The YT-100 will not automatically initiate a tuning cycle when there is high SWR present.

There is, however, a simple solution to your problem. The YT-100 has a 1/8 inch jack that facilitates a remote tune button (see page 16 of the manual). You could run a shielded, decoupled cable to a push button at a convenient location; you could use an RF keychain remote control device to avoid the use of the cable all together; or you could connect the input to a TCP/IP switch to toggle it remotely from your PC.

If you are comfortable with homebrewing, you could put an SWR detector circuit on the input of the tuner that automatically triggers a tune cycle if a given SWR threshhold is exceeded.

  • 1
    $\begingroup$ Thanks Glenn. I'm thinking something like an arduino attached by USB to the shack PC which can trigger an opto isolator to do the tune. Arduino is probably overkill but it makes USB connection easier and I can probably extend it to do other stuff later too. $\endgroup$
    – MattC
    May 3, 2018 at 13:19
  • $\begingroup$ @MattC That sounds like fun. Enjoy the project! $\endgroup$
    – Glenn W9IQ
    May 3, 2018 at 13:28
  • $\begingroup$ Yes, @MattC, it would be a perfect companion to a Raspberry Pi (making what I call a Piduino). You can load the Arduino IDE on the Pi and access it via WiFi. It can send commands via USB (/dev/USB0 usually) via Python or even miniterm. Then the Arduino could pick up the command and execute it. So it would not need a long cable to your PC at all. $\endgroup$
    – SDsolar
    May 4, 2018 at 2:15

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