Until now, I have been using the Aerial-51 Model 404-UL antenna installed on a 12-meter Spiderbeam telescopic mast for portable operation. Although this setup delivers very good performance, its installation is often quite demanding in terms of the space required.
For this reason, I decided to purchase a Yaesu ATAS-120A antenna for use with my Yaesu FT-857D and create a more compact system suitable for quick deployment, even in locations where space is limited.
Since I wanted to make use of the K&F Concept K234A7 tripod with the FH-03 ball head, which I normally use for satellite operation, I designed my own custom mount for the ATAS-120A. The result is a compact mounting solution that can be used together with the WiMo Counterpoise Kit, allowing several installation configurations described below.
Technical Documentation
The mount was designed using FreeCAD. The PDF document below contains several 3D views of the model together with fully dimensioned 2D drawings required for manufacturing.
The drawing package is provided for reference, personal use, and further development of the project.
If you are interested in the original CAD model, the STEP file can be provided upon request.
Tripod Mount Details
The photographs below show the completed mount before and after the installation of the RF connectors.
To keep the installation compact and visually clean, the coaxial cable is routed internally through the mount body. Since H155 is used throughout the rest of my portable setup, I decided to use the same cable inside the mount as well.
Due to the cable diameter and limited internal space, routing the H155 through the mount proved to be quite a challenge. Particular attention had to be paid to the orientation of the solder lugs connected to the coaxial shield. The lugs had to be aligned with the dedicated 0.5 mm deep recesses located next to one of the M3 mounting holes used to secure the UHF connectors.
Option A – WiMo Counterpoise Kit with Integrated Radial Mount
The photographs show the WiMo Counterpoise Kit radials mounted directly to the tripod mount. The mount was originally designed with six threaded holes intended for conventional wire radials placed on the ground. During the design process, however, the concept was revised to incorporate eight mounting points compatible with the WiMo Counterpoise Kit, eliminating the need for the original counterpoise ring and creating a compact and mechanically robust assembly.
With the tripod fully extended, the antenna feed point is approximately 2 meters above ground level.
Option B – WiMo Counterpoise Kit with Original Counterpoise Ring
The photographs below show the WiMo Counterpoise Kit installed using the original WiMo counterpoise ring. This configuration follows the manufacturer’s recommended installation method and requires no modifications to the counterpoise system.
While the original ring slightly increases the overall size of the assembly, it offers a simple and proven solution that can be easily transferred between different ATAS-120A installations.
With the tripod fully extended, the antenna feed point is approximately 2 meters above ground level.
Conclusion
The project successfully transformed an existing satellite tripod into a compact and versatile mounting platform for the Yaesu ATAS-120A. Both counterpoise configurations work well and provide a practical solution for portable operation where space is limited.
Further field testing will determine which configuration becomes my preferred choice for everyday portable use.
OK1TK HAM Radio 