March 6, 2025
16:30
by: Dan

IRYS Yaesu-to-Icom Tuner Adapter

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Overview

The IRYS device lets you control Icom AH-4 compatible tuners (including LDG) from your Yaesu radio natively. This means the radio controls the tuner, indicates the tuning state on the screen, and does not require use of the key jack to do this. Benefits:
  • Use your native “TUNE” button on the radio, see tuner status on the screen
  • Remote-mount a tuner, control it from the radio
  • Access the much wider range of available tuners for Icom radios with your Yaesu
  • Retain the ability to use your remote keypad *and* an external tuner!
  • Tuner is powered from the radio (like an Icom radio does, when supported by the tuner)
  • Manual activation button for times when the radio refuses to initiate the tuner due to high SWR
I designed this so that people at field day with Yaesu radios can use their voice keyer keypad and an external tuner at the same time. It also brings the extra benefit of being able to swap antennas and tuners with Icom users!
 
This has been tested with the following radios:
  • Yaesu FT-450
  • Yaesu FT-710
  • Yaesu FT-891
  • Yaesu FT-991A
  • Yaesu FTDX10
  • Yaesu FTDX101MP
  • Vertex Standard VX-1700
It should work with any Yaesu radio that supports the FC-40 tuner (i.e. FT-857, FT-897, etc), but the above have been tested. It should also work with any tuner that implements the AH-4 tuner protocol, but the following have been tested:
  • Icom AH-4, AH-730, AT-120, AH-2
  • LDG Z-100A, IT-100 (and friends) with the IC-100 cable
  • LDG AT-100/200/600/1000 Pro-II with the IC-PAC cable
  • MFJ-929
The device has an 8-pin Mini-DIN plug that interfaces with your Yaesu radio’s TUNER/LIN jack, and provides a 4-pin Molex connector for connection to an Icom-compatible tuner.
 

Versions

In mid-June 2025 IRYS rev4 hardware was released, which includes the following changes:

  • A manual-tune button for triggering the tuner directly. This allows manual tuning (in a constant-power mode like CW) for situations where the radio refuses to drive the tuner itself due to high SWR.
  • Exposed LEDs for better status and troubleshooting
  • A dedicated AH4 mode which disables the un-bypass action on the radio when used exclusively with the AH4 (which supports bypass but not un-bypass).

Notes and Errata

  1. It is important to understand that this is an adapter. It intends to make two incompatible devices talk to each other that were not meant to. Even though this works very well for most people, it is not perfect and you should not expect 100% seamless operation. However, for my purposes it works extremely well and opens up Yaesu owners to a much wider array of available tuners.
  2. I have received one report that the MFJ-939B tuner does not operate properly with the adapter (hence why it is not on the supported list above). It is workable, but requires three attempts to operate the tuner each time (the first two fail to initialize the tuner, but the third always works). This may be something I can work around, but I will have to get my hands on one to reproduce and test a fix.
  3. The power provided by the Yaesu radios via the tuner is much less than the Icom tuner jack. Even though the AH-4 and LDG tuners are very power-efficient, keep in mind that all the power for everything in the tuner chain comes from a tiny pin in the Mini-DIN connector. Make sure you have reasonably-sized control wire conductors, that they are in good condition, and that your connector mates securely.
  4. Yaesu radios (unlike Icoms) appear to “second guess” the tuner. If they determine that the initial pre-tune SWR is higher than what they think the FC-40 will be able to match (about 5:1), they will abort the tune immediately and not give the tuner a chance to make a match. Even though LDG and Icom tuners can generally do a much better job than the Yaesu FC-40, the radios will not always cooperate. The radio must provide RF for the tuners to work, and if the radio decides to abort, the tuner has no recourse. The IRYS adapter cannot force the radio to continue providing RF in that case. This usually manifests as the tuner working fine on some bands and not others, where the radio appears to “give up” immediately. Workarounds for Yaesu’s extremely unfortunate design decision are:
    1. IRYSrev4B owners can use the manual tuning button on the device to force the radio to drive the tuner with a constant-power mode (like CW). Details on this are in the instructions.
    2. If using a long-wire antenna, try adjusting the length of your antenna to move extreme SWR spikes outside of the bands you wish to tune.
    3. You may also try switching a dummy load in parallel with the radio-to-tuner RF path. That will lower the perceived SWR at the radio and convince it to tune a much wide range (just remember to switch it out for actual use!).

Resources

Here are some links that may be helpful:

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