Some Ideas for Tower Trailers

Bob Lear, W4ZST, presents the approach of the Fourlanders Contesting Team for building and using tower trailers for contesting portability.

Some history and impetus for these ideas.

An accompanying PowerPoint presentation is available here.

Most of these ideas come from the ages. Actually the ages of our contesting participants as we began having more problems with transporting, assembling and walking-up real towers for our contesting efforts. Those physical efforts were getting to some of us. Not to mention the safety issues involved with walking-up towers with rotors and antennas installed. Fortunately, some lights flashed and several ideas for improving the situation came to mind and physical fruition. These ideas should be useful for contesting or any portable operations including Field Day and Emergency Communications events. What follows is a combination rambling history of my tower trailer experiences with the Fourlanders, ideas realized and some details of design and construction. You’ll also find that I have a penchant for naming these trailers.

Our main usage is for portable contesting operation. The FourLanders VHF/UHF Contest Team has been active for twenty plus years in the June and September ARRL VHF QSO Parties. Over the years the group has operated from many locations around the southeast, many different amateur operator participants have been involved and many call signs used. The group has varied in size from as many as fifty to our present unfortunately small core group of less than ten members. I was not a participant when the group was at it’s largest, but I can certainly imagine how much easier it would have been to set up a large multi-op contest effort with that many folks. I have only had experience with the group sizes from 5 to 15 members, doing either limited or full multi-op for the past seven years or so. With the smaller size group of participants, we have been forced many times to choose between full multi and limited or unfortunately even whether to participate in a contest. I can tell you that the four of us who attempted four band limited for one contest decided that we wouldn’t want to do it again with only four participants. There is work involved in any portable operation set-up and making it quicker and easier has been our goal as the group has gotten smaller and the participants age. We have tried to recruit more members to help with the size problem, but haven’t made much progress with the age issue!

The “BlackHawk”, our first trailer: The tower on this trailer was donated to another local club years ago and was used with an erection A-frame for some time, until one of the members designed and welded up a trailer to accommodate the tower and A-frame. The FourLanders borrowed this trailer from the other club for years to use for the VHF contests as there were many common members. Eventually the other club usage declined and it became excess to their needs and it was purchased for the FourLanders use. Some of us do use it for Field Day with yet another club group. The tower is a two-section commercial crank-up tower, reinforced and hinged at the base mounted toward the rear of the trailer. There is a winch and cable over the top of the A-frame to raise the tower to the upright position. It will handle plenty of antenna. It is currently used for a stacked pair of 5 element K1FO style 6m antennas with 17’ booms designed and built by K5AND for the club. The tower trailer had also been used for a long time with a stacked pair of 2M5WL’s spaced at 16’ for the contests.   We have put a 20m 4 el beam or a full size tribander on it at different Field Days. The trailer is exceptionally stable with the outriggers extended to level it up and get the tires off the ground. The added wood deck has made it easier to use the trailer to carry gear such as ladders and masts to the contest site and interestingly made it easier to pull with the added weight. As you can imagine, it is “front-bouncy” because of the overhanging tower leverage. The added weight helped the pulling feel on the road. A trailer built along these lines to accommodate a surplus tower can be quite useful. This one is built using mobile home axles, wheels and tires and the axle undercarriage is clamped to the frame, i.e. the undercarriage could be removed and the trailer frame would sit flat on the ground or on the outriggers. See photos BlackHawk1, 2 & 3.

The “Green Hornet”: I had purchased a surplus military mast at a hamfest and let it sit around for a year or so before I was inspired one day to mate it with an old boat trailer and satellite dish roof mount tripod sitting around the yard. Yes, my yard does look like Fred Sanford’s most of the time. On the day I came up with the idea, I made some quick measurements, decided it would work and after observing the construction of the boat trailer decided to use the same method: holding the tripod on with square U-bolts. I managed to get it put together and cranked up with a 5 el 6m beam and rotator installed before dark that day. It was very satisfying to make such progress so quickly. This trailer has been used mostly for 222 during the contests, first with a single long boom yagi and later with a single K1FO-16 above the top mounted rotator. It did require an 8 or 10 foot stepladder to safely assemble with a single beam although we did manage a smaller vertically polarized beam at the top of the mast above the main yagi a time or two. I kept trying to think of a way to install a stacked pair of K1FO’s on this mast and trailer. I finally did after getting more inspiration from the next two trailers. This trailer and mast were also used for several years to mount the VHF-LP source antenna for the SVHFS conference antenna range. This trailer was nicknamed “Green Hornet”. The photographs and sketches illustrate the construction ideas that may be adapted to other situations. See photos Green_Hornet1, 2 & 3.

The “Radio Flyer”: I had another tower sitting around the (junk) yard for a year or two. It was a Rohn 55’ three section crank-up. One day it occurred to me that I could mount it on my equipment hauling trailer (7’x18’, double axle, 5000 pound load) that was only being used to haul my tractor and such items and not for the noble cause of radio contesting. Well, no longer was it to be an orphan. Actually, we did use it to haul the many 10’ tower sections we used to have to carry to the mountain-top, before the tower trailer age, along with the golf cart. (It turns out we really are just lazy old men.) I made some measurements, inspected the crank-up tower, made some sketches and decided that I could cut the tower in half, put both on the big trailer, haul them laying flat, have them tilt up and still get the golf cart on it for the trip. (More proof). I was excited by then and started cutting metal. As you can see from the pictures, I ended up with two 30’ tilt-up, crank-ups separated by 15 feet. This turns out to be OK for the stacked pair of 432 K1FO’s on one and the microwave goodies on the other for 903 and up. The height also is OK for us as the 30’ pretty much clears all the vegetation on our mountain-top contesting location. I might have wanted to keep the tower in one piece and do something different for some other location. At 5300’ on a bald mountain-top a few more feet aren’t going to make much difference. I really didn’t need to go with the out-riggers. The trailer is large and heavy enough that I would only have needed the jacks for leveling and not really for stability. It is quite over-engineered, but it is done now and I’m not cutting those pieces back out. The location of the pivot supports I think were an interesting way to do this and retain normal use of my trailer (if anything I do could be considered normal). I was inspired by BlackHawk (and that ancient Greek geometer & philosopher, Isoceles) for the triangular support used to pull up and support the masts, but I found a way to make it all removable for normal trailer function. The metal work is probably over-engineered for these applications, but we haven’t had any problems with it. It is very sturdy and we have experienced some pretty high winds with all the different trailers used on that 5300’ mountain, having no problems with any of them. From the photos of the finished trailer in use, you should have no trouble seeing why this one is called “Radio Flyer”. See photos Radio_Flyer1, 2 & 3.

The two towers on this trailer have no problem with stacking the pair of ‘FO25’s for 432

And whatever microwave set up we do for a particular contest. We have had 33 el on 903, 2X45 el on 1296, blowtorches on 2304 and 3456 and a DEMI dual band feed dish for 5760 and 10GHz up a couple of times when we had gear for all those bands available. Once we even had the 5 & 10 transverters and amps mounted behind the dish.

The “White Knight”: The next trailer in our repertoire came somewhat by accident. I was purchasing steel for the “Radio Flyer” and describing what I was doing to another customer waiting there and he said I might be interested in a trailer he had for sale. It turned out to be a small industrial lighting trailer, without the light bar or generator, but useable without modification for our purposes so I snapped it up. As you can see from the photos it has a 10 meter collapsible crank-up, tilt-over mast and outriggers. It is quite small, but stable enough with the outriggers. It also has been used for the conference antenna range. We started using this trailer for 222 with a stacked pair of the K1FO’s as the array was quite easy to assemble with the mast in the tilted over position. This is also a top-mount rotator application. This trailer is small but deceptively sturdy. It is all steel and weighs over 1000 pounds. It pulls nicely for such a small trailer. I’ve pulled it as far as 200 miles. We’ve nicknamed this one the “White Knight”. Keep your eyes out for items like this from other industries that you might not have thought of before. You might make a good deal too.   An interesting feature is the single winch to both tilt the mast upright and raise it to height. There is a nice explanation of this on an internet site where the op did it with a fixed location tilt-over tower. It would not be difficult to duplicate with or without the automatic latches, which shouldn’t be necessary anyway for our typical amateur applications. See photos White_Knight1 & 2.

“T-Rex”: As I mentioned for the “Green Hornet” it was too difficult to stack a pair on that set-up with having to work off a step ladder and not having another 10’ or so to be able to set-up and connect an upper antenna. Dick K5AND came up with an idea and together we mounted his modified military mast on yet another 5×10 utility trailer that was then used to stack a pair of K5AND design 17’, 12 el 2 meter beams. Dick chose to bottom mount the rotator to rotate the entire mast and antenna assembly. Dick designed and had a rotating support bearing built that goes at the top of the mast bottom section. The original rotation assembly worked all right with the intended military ‘armstrong’ rotation method, but wouldn’t rotate with the power rotator and load we were putting on it. The set-up work is still done off a ladder, but he also devised an internal, keyed pull-up mast. The top antenna is mounted, the mast pulled up to mid-point, the power divider mounted and connected and then the mast pulled up and the lower antenna mounted. A locking ring secures the mast at it’s intended height. It did require some juggling and two folks to assemble, but has worked very well for the contests. This trailer was dubbed “T-Rex” for the ‘Trex’ brand composite decking material used. Rear leveling jacks were added for three-point adjustment, along with the corner posts to guy off the mast from the rotating support bearing. Plenty of room on this trailer for hauling the mast, generator and the necessary food and beverage coolers. Details of the bearing, rotator mount and other aspects of this trailer’s construction are shown in the photos. See photos T-Rex1, 2, 3, & 4.

The “Black Knight”: K5AND moved to Texas and took T-Rex with him so we had to come up with another 2m tower trailer. I could have duplicated his design, but I had another inspiration that turned out to take less time to implement. I decided to make the “Green Hornet” idea in to a tilt-over design. We secured another 5X10 utility trailer, installed rear corner jacks for leveling and I devised a hinge mechanism and clamps to allow for easy tilt-up and securing in the upright position. Here we top-mount the rotator, use a 9’ mast and install and wire the antennas in the tilted-down position. Very easy installation. We still do need to get on the ladder to align the system to North before operating, but this is easy to do. Or, if the trailer is situated with the bottom end of the mast due N-S before tilting up, it is automatically aligned if the antennas were installed with masts horizontal to the ground (and in the proper left-right direction to end up E-W and the rotor preset). That sounds confusing, but if you see it on the ground it is just as easy to do. This trailer and pertinent details are shown in the photos. Unfortunately we haven’t come up with a great name for this one yet. I’ve been thinking “Black Knight” or “Black Mamba” (another comic book character) or maybe we should repaint it!? I have been experimenting with this one here at the home QTH and I can set it up with a stacked pair (2, 222 or 432: tried all three combos for sprints) by myself in very little time. I spent more time carrying the antennas from storage to the trailer and getting little things like tape and jumpers than I did on actual set-up labor. I have more than enough weight to tilt the mast up even with the added rotator, mast and antennas installed. A winch could easily be adapted for the tilt-up mechanism I the future. I may actually do that sometime just to show how it’s done as there may come a time when that will be more desirable than using myself as a counterweight. Yeah, what if I actually lost some weight? Things have been so hectic that I failed to take photos of this trailer during the construction like I meant to. There is a shot of it on Photo BlackHawk2. This trailer is also in use for the antenna range at this conference.

So, we have over the years, gone from assembling Rohn tower sections and walking those up to be guyed off with rope or wire, then climbing to connect hard lines and dress the rotator loops and align azimuth to much more labor saving tower trailers. The biggest problem we have now is enough folks to pull the trailers to the contest site. You see, we also have the two cargo trailers used for the operating positions and a new diesel generator which is on it’s own trailer. This has called for some piggy backing to be done for the last couple of contests. We carried White Knight inside the 20’ cargo trailer, appropriately named “Great White” and loaded the newest trailer Black Knight onto the Radio Flyer. One can be done by two people manually, but the White Knight needs a vehicle and hitch to get it loaded up the ramps since it is quite heavy.

I hope these ideas will be of use to some of you for portable operations and will inspire some new ideas that you can share also.



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