I (Eric – VA7NX) enjoy operating at parks in the Parks-on-the-Air program. In this program one takes a portable station to parks on the approved list and make radio contacts in any of the bands and modes. Reaching ten contacts or more constitutes a completed activation.  One of my requirements for a good operation is the speed at which I can set up my equipment and then pack it away. I want a simple set up that is easy to put up yet effective across multiple bands.

To achieve this, I use an OCF dipole from Spiderbeam. This antenna is raised with a centre mast of 40 feet. I use an Elecraft KX3 into the 100-watt amp to provide the transceiver portion of the station. Raising the mast is a major part of the time needed to get set up. As such I have looked for ways to streamline the process. Having long guy ropes is one thing I eliminate as they are not only more time consuming to deploy but also a hazard to the public which wander by in a park. Eliminating guys puts more stress on the support component of the tripod. To replace the guy wires, I anchor each leg with a stake to prevent tipping.

The lower support of the tripod has to securely hold the mast even when there is a breeze pushing the set up over. I have tried a number of methods of securing the mast to the tripod using various lengths of ABS pipes and couplers but all have fallen short of a good secure base.  Generally, the depth of the support is not sufficient to keep the mast in place should wind push on the mast or if the ground is unlevel. After several attempts of constructing the base from off the shelf components I gave up and decided to build my own. I acquired a 3d printer and loaded the OpenSCAD software to design the fixture that would be quick to use and provide good support.

The designing of the fixture was quite easy in the design language provided by the OpenSCAD software and the whole program design took only a few lines of coding. The end result was a hollow cylinder attached to a smaller solid one. The solid cylinder would be held by the tripod clamps and the larger would hold the mast. The sizing was such that it would be a snug fit but not too tight as to make it slow to use. It could also be left in place when the tripod is folded up for packing.

Once I had the fixture designed, I produced a smaller scaled version to test the strength of the PLA material for this application. As it was my first 3d project, I wasn’t sure of the strength of this plastic. After reviewing the small model I felt that it was adequate and so I printed off the full-size version. Once cooled I peeled it off the printer bed and slipped the mast end into it. It fit perfectly. Just enough room to slide in easily without much slop. The smaller cylinder just squeezed into the mast support and was soon clamped in position. The design worked well. But I still needed to try it at a park.

On my next park activation, I set up the tripod as usual and set the mast into the new base. It was fast and when raised, it held the mast securely even when leaning. It was going to work well. The added bonus of this approach is that should it break I can quickly make another!