Part of our FT-891: The Complete Guide.
The FT-891 doesn’t have an internal tuner, which is one of the tradeoffs you accept for the compact size. I went through a couple of options before landing on the one I actually keep in rotation.
Why an external tuner is non-negotiable here
Unlike the G90 or the FTX-1 Optima, the 891 gives you zero built-in help matching an imperfect antenna. Run it into anything other than a truly resonant antenna and you need something in line, whether that’s a manual tuner you ride by hand or an automatic box that does the work for you.
Why I Use the MFJ-939
The short answer, it was given to me by a friend. I had the FT-891 but did not have a tuner and he happened to have the MFJ-939 sitting on a shelf. That said, the MFJ-939 is an automatic tuner, and paired with the Yaesu-specific adapter cable, it talks directly to the FT-891’s tuner control line, so tuning is a single button press on the radio rather than a separate control head to manage.
How it actually performs
I like this tuner a lot. It finds a match quickly, holds it reliably, and the Yaesu adapter cable means the FT-891’s own tune button drives the whole process without any extra steps. It’s not the smallest box in the world, but it’s not trying to be a Field Head accessory either, it’s built for a shack or vehicle install where a bit of size is an acceptable tradeoff for a wider matching range and a proven track record.
Setup notes
Get the correct Yaesu adapter cable for the 891 specifically, MFJ sells radio-specific versions and the wrong one won’t give you single-button tuning from the radio. Beyond that, treat it like any other automatic tuner: tune at reduced power on a new band or antenna before running full output, and let it store memories for your regular setups so retuning is fast on repeat sessions.
What I’d tell someone shopping for one
- Get the Yaesu-specific adapter cable, not a generic tuner control cable, to get single-button tuning from the 891.
- Confirm the tuner’s matching range covers the antennas you actually run before buying, not just the one you have today.
- Tune at low power on any new band or antenna before running full output.
- Budget for the tuner as part of the FT-891 purchase, not an afterthought, since the radio genuinely needs one.
It’s not flashy, but the MFJ-939 has been reliable enough that I don’t think about it much anymore, which is exactly what I want from a tuner. I bring it along whenever I’m not running the ATAS-120A in the Jeep, see my FT-891 field kit walkthrough for how it fits into the rest of the gear.