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A Portable 6 Meter Beam Set-up for a Pickup Truck


Some months ago I got interested in operating mobile as a result of the possible need for TARC Members to assist with communications for a bicycling event. I was about to buy another Icom 2200h for my truck since I use a 2200 at home for 2m net operating, when a discussion on W4JS' weekly TARC DX Net about sporadic E propagation on 6 meters expanded the scope of my mobile interest.


My HF base rig, an FT-1000MP, is a super transceiver but it pre-dates when 6 meter coverage became a standard feature in HF transceivers. I did look for a used 6m rig but didn't find anything I wanted. I was about to give up the 6m notion when a friend called about an ad he'd seen for a used Icom 706 MK II G. This seemed interesting as I could cover 2m, 6m and have a backup HF rig all in one. He seemed quite happy with his 706 and the eHam reviews are generally very good.


 


I wasn't so much interested in driving and operating but more in finding a spot to park by the Gulf and set up a portable station to see what could be worked with 100 watts. A magnetic whip on the cab of the truck would suffice for 2m, but to try for 6m DX using SSB and low power, a larger and horizontally polarized antenna would be needed. I had seen a pickup truck at the Orlando Hamfest outfitted with a mast and since I had some military surplus mast sections lying around, the truck bed seemed like the perfect base for a portable 3 element 6m beam. The mast had to be quick and easy to set up and take down, fairly sturdy and able to be rotated. The military surplus mast sections were the answer. The mast sections are available from The Mast Company  (www.tmastco.com) and I'm sure many other sources including hamfests. The sections are heavy duty aluminum that are 48 inches long and slip snugly together with a 3 ½ inch overlap. Four or five of these sections mounted on a truck bed can raise an antenna to 20 feet or so. With the available guy rings the mast can be made quite sturdy.



 




 



It's probably not a good idea to be driving around with a 20ft. mast and a 3 element beam on the back of the truck so how do we set all this up for safe transport, quick set-up and operating? My solution was to mount one section of mast in the center of the truck bed, firmly guyed to the 4 anchors in each corner with ratchet type nylon tie-downs. This is removable, but it's a solid base for transporting the antenna and for building the remaining mast sections on top.


 

The boom of my 6m beam is just wider than the truck, but within the width of the side mirrors, so fitting the beam with a one foot mast stub that slips onto the bottom mast section and orientating the beam with the elements in line with the truck is an easy way to safely transport the antenna. The stub is pinned through the bottom mast section so that it will not rotate while I'm driving.



Once at the operating site, the remaining mast sections are fitted one-by-one, pinning each, until the next-to-last section is mounted into the bottom section without a pin. This allows rotation of the beam. The coax feedline is run through a window to a 2-position switch allowing convenient switching between a 20m whip and the 6m beam.




I'm sorry to say that I did not get this project completed in a timely fashion to work any sporadic E on 6 meters but I have tested the transporting and raising and lowering of the beam and found it all to work easily for one person using 4 mast sections. Any higher would require two people to manage the final installation steps. Perhaps it will get its first real test next Field Day. I have worked a number of DX QSOs from the mobile rig on 20m and being close to the water seems to be the ticket when running low power mobile.





73,

Jack/KY1Z