I’ve already built some ATU-100 automatic antenna tuners in the past: One was a build for QRO and one for QRP with only 5 windings on the binocular transformer and adaptions to the original firmware. While the QRO version worked fine, I had issues with the QRP variant. After I’ve discovered the very nice alternative firmware of DG4SN I’ve decided to build an ATU-100 based phantom powered remote antenna tuner that can be mounted on the mast directly beneath my M0PLK Delta Loop. The nice thing with DG4SN’s firmware is that it allows QRP operation with the original 10 windings on each side of the transformator.

I found a nice waterproof enclusure with the perfect measurements but without any possibilities to mount it to a mast. So the first thing to do was to add four M4 brass threads that were melted into the ABS enclosure on the back:

Two 3D printed t-shaped parts were then screwed to the enclosure. With them, the enclosure can be mounted to the mast with zip ties or big hose clamps:

To be able to mount the ATU-100, the Bias-T and the display inside the enclosure, I’ve designed a simple inlay and printed it in PETG:

This is how the tuner looks like with all components mounted and wired together:

I sadly had to use hotglue because the screw head of one of the screws that hold the display broke off.