Really Rugged Coils Antenna System
In my construction article published in the 2014 May issue of QST on how to build a 17 meter HF monobander for your mobile, I described how to utilize PL-259 connectors for building a unique style of antenna that utilizes coils with PL-259 connectors as part of the coil assembly.
The PL-259 connector works well for this application, and I have since carried it further by utilizing them in several of my latest HF mobile antennas.
Having said that, I have actually changed the design of the coils somewhat, making for a much more robust coil assembly, as well as a coil that has a higher Q rating due to less metal being utilized in the build of the coil.
I build the coliform from 3 pieces of Delrin that I turn to shape in the lathe, that being the main Delrin coliform tube section with the two Delrin endcaps.
The coilform is wound with 14 gauge wire with 8 tpi spacing that I cut in the lathe.
To build the mounting hardware at either end of these coils, I initially start with a UHF to BNC rf connector.
I remove the BNC end and then with the remaining UHF end, I make the modifications required.
I replace the center insulators of the UHF rf connector at either end of the coil with solid brass machined inserts to increase the ruggedness of the coil.
There is no need for an insulator, as the screw-threads at either end of the coil are conductive, and all the center pins in the PL-259's are utilized for are alignment when changing out coils.
All of the coils that make up my RRC (Really Rugged Coils Antenna System) utilize the same mast and 60 inch whip.
I also designed and built the RRC antenna system to handle 500 watts of rf power.
Also my coils are sealed against any and all weather that may occur with temperatures ranging from -40C to +40C
Click on the photo for a closer look.....
Here is a another look with an insert photo that shows the modification on the UHF rf connector at either end of the coil.....