|Portable Mast Support -
Craig LaBarge, WB3GCK
Iwas in need of a way to support a lightweight, 28-foot fiberglass mast (www.jackite.com), during portable operation. For my work with our local ARES-RACES group, I sometimes need to quickly get a twinlead J-pole up high for better coverage. Being a long-time QRP operator, I also have an occasional need to support a lightweight inverted vee antenna during the various QRP field contests held each year.
Looking at various options, I came across some real nice commerical "roll-on" supports. Unfortunately, some came with price tags in the hundreds of dollars. Plus, their heavy steel construction was overkill for the lightweight mast that I use. So, in true ham tradition, I decided to raid the junk box to see what I could cobble together.
My initial mast support (shown in the accompanying pictures) was nothing more than 2-foot scrap piece of pressure-treated 1x6 lumber, a threaded pipe flange, and a 1-foot piece of 1-inch threaded steel pipe. The flange is bolted to one end of the board, using 1/4-20 x 1-1/2-inch flathead bolts countersunk into the underside of the board. Mine are a bit longer than they need to be; that's what I had on hand. The 1-inch threaded pipe is then screwed into the pipe flange.
I chose the 1-inch steel pipe because it was the closest fit to the inside of the bottom section of my mast. Your mast may be different, so select the pipe size accordingly. In my case, I needed to wrap a few layers of duct tape and electrical tape around the pipe to get a snug fit up inside the mast.
In use, you just need to park with one of your vehicle's tires on top of the board, place the mast over the pipe and you're in business.
I also made up an adapter to fit my Black Widow 20-foot telescopic pole (www.bnmpoles.com). For the Black Widow pole support, I needed a 3/4-inch pipe. I used a 1-inch threaded fitting, a 2-inch piece of 1-inch PVC pipe, a 1-inch to 3/4-inch reducer and a 1-foot piece of 3/4-inch PVC pipe. The picture shows the pipe prior to adding some duct tape to improve the fit.
For my Jackite 31-foot pole, I built another version using a 1-1/4 inch floor flange and an 18-inch length of 1-1/4 inch threaded pipe. This one was made with a piece of 1x6 maple that was leftover from a home improvement project. I have adapters (reducers) to accomodate 3/4-inch and 1-inch pipes.
The total cost for the mast support was just a few dollars for the pipe and flange in the plumbing section of the local home improvement store. This design is more that sufficient for a lightweight, telescopic fiberglass mast. If you need to support something heavier, like a steel mast, you'll need a more robust support than this.
Mast Support in Use