Telescoping Antenna Masts

A good rover mast will be tall, lightweight, easy to assemble and strong. Click on images to see what I've used.

Painter's Pole - Fiberglass

An 18-foot painter's pole makes an inexpensive mast for lightweight antennas. This worked well for smaller yagi's; for the 2013 Field Day it supported a 2-element 6-meter beam along with a 3-element 144/432 beam.

Source: Home Depot

However, fiberglass poles are not strong enough to take much load. I discovered this startling fact in October 2013 on top of Dixie Butte, with my friend Dennis K7FL. My cheap painter's pole collapsed under combined the weight of a 5-element 6-meter beam plus 7-element 2-meter beam. Imagine Dennis's surprise to be crushed by a big falling antenna system at 7000' of elevation and many miles from civilization. Thankfully, the antennas were not damaged.

Aluminum Telescoping Mast

The goals of the replacement mast are to:

• Aluminum (fiberglass is too flexible)
• Hold 5-el 6m beam at 20' (M2 6M5)
• Also hold 7-el 2m beam at 24 (M2 2M7)
• Telescoping
• One man setup / takedown
• Assemble and raise while wearing gloves (no small fiddly parts)
• Safe (redundant devices to hold extended)
• Okay to use bolts and power driver (all nuts same size)
• Okay to use one set of guys
• Mount on trailer hitch adapter (not tripod or drive on)
• Rotate by turning mast (not rope steering)
• Able to store on roof rack

I want a push-up mast (not tilt-up, for strength) but this design will pin sections together which requires tilt-up.

The photo below shows the new replacement 24' telescoping aluminum mast supporting three good-sized VHF antennas at a campsite in Camp Blanco State Park, Oregon. The next photo provides a sense of scale when the mast is nested down; I don't drive this way although it coulld probably be done, with the addition of ropes for stability.

Aluminum Mast Tubing Parts List

The mast is five 6' sections from DX Engineering. The two bottom sections are thick-wall (0.120") tubing for strength, and the three top sections are thin-wall (0.058") tubing to save weight. The prices were current in November 2013.

The tubes are drilled to receive pins. It is actually pretty to drill accurately centered holes on round stock. I highly recommend using a drill press and alignment jig.

The top ends have holes at 18" and 24", while the bottom end is drilled at 6". This is designed for easy hole-finding during set-up in adverse conditions. Do you remember how hard it is to align mast sections during, say, Field Day in the warm sun? Now imagine doing that alone, in the dark, with cold hands in freezing temperatures and gloves, working by yourself.

If I were to build another mast, I'd replace some of the thin-walled tubes with thick-wall tubing, making it stronger and stiffer. Since my excursions are usually to remote hilltops in the Pacific Northwest, far from civilization, and I usually have large, heavy antennas, then I would choose to improve strength over height.

Mast Construction Hardware

During set-up on site, my assembly process is to insert a pin in the 24" hole. Then slide the next pipe down to rest on the pin. Now it's a simple matter to rotate the upper pipe until the holes align, and drop in the pin at the 18" mark, locking the sections together. These are snap lock safety pins. No tools are required.

Here's the mast mounting arrangement for the 6-meter beam. The U-bolts are permanently affixed on the tubing. They are exactly aligned to mate with the antennas mounting plate holes. The ends of these U-bolts are long enough to pass through the plate and receive nuts.

Note that these saddle clamps will deform the tubing slightly. They will put some pressure on the inside tubing section, and can make it difficult to extend upper-level telescoping sections. Be careful during tightening; make it tight enough to hold but don't crank the saddle bolts down too tightly.

The clip rings on the safety pins are a convenient way to secure the coax cable to the mast.

Cleaning

These tubes were manufactured with close tolerances and precision machining. They must be dried and cleaned after every trip.

On my return home, the aluminum tubes are laid out separately to dry. Wipe the outsides with a clean cloth, and pull a cloth through the middle of the tubes to remove dirt and particles. Finally, polish the outsides with a paste car wax. Reassemble the sections can be reassembled for storage in a dry garage.

Conclusion

How well does it all work? It meets all my goals except "push up assembly." The way the tubes nest together requires them to be pinned from the bottom, working my way upward. Therefore it must be assembled laying down on a simple support system and then tipped up into place.

Source: DX Engineering. See their catalog for prices, but you can expect to spend a few hundred dollars for all the telescoping tubes, stainless steel hose clamps, hardware and plastic guy rings.