LA1K / LA100K / LA1UKA

Yaesu G-1000DXC input transformer replacement

In this short entry we show how we fixed what seems to be a fairly common issue with Yaesu’s G-1000DXC azimuth rotor controllers.

The problem was that the front panel of the controller was unresponsive. After opening the chassis to diagnose the fault, we discovered that the primary side of the mains voltage input transformer had become open. Several other hams also report similar issues, which leads us to believe that the problem stems from a fairly common event such as voltage spike or current surge. Further, the input has no clamping against such faults, so damage is likely.

The faulty input transformer, marked KT-28-E-3.

The fix is to simply replace the KT-28-E-3 transformer. Our solution was to reach out to WiMo and hear if they had some spare parts in stock, and luckily they did. Other alternatives include salvage, or attempting to repair/rewind the original core. See the two schematic cutouts below for specs of the transformers.

The transformer is accessed by removing the top lid and the electronics board. These are fastened with screws on the upper back of the rear panel and the front of the top panel. Further, the connectors to the electronics board must be temporarily detached.

We elected to attach the new transformer in the laziest conceivable way, by using wago 221 wire clamps on stripped cables.

Cable ties installed, connectors reinserted.

With everything re-assembled, all that remains is to test that is functions properly.



  1. Gavala 1

    Looking at the manual, the rotor voltage is 11 – 24 Vdc and not 28Vac.
    Would you be able to clarify anything I’m not aware of?

    • LA3WUA


      It’s been some time since I looked into this, but I believe that this is the transformer seen on page 17 here (, so it would appear that I’ve made an error in the original post. I’ll update it so that it less confusing.

      73s LA3WUA

      • Gavala 1

        No problem.
        What is this skiiing to a portable location? A wonderful life and such a nice club with a mixed age group.
        Good luck.

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