Backpacking radio's big and getting bigger - but what are you going to use for an antenna? When you're a long way from the nearest AC outlet you need all the gain you can get that doesn't eat precious amps. You can't pack a seventeen element yagi on a tower, but a portable beam, together with some way to hoist it into the ether, would sound just the ticket.
SOTA - Summits On The Air - is an organisation dedicated to ruining a nice country walk with all that amateur radio nonsense, and to go with it radioactive rambler supremo Richard Newstead, G3CWI, has set up SOTA Beams. Its first product is called just the SOTA Beam -- no WundaYagi Xtreem 3000 Pro type product names for these guys, thank goodness.
The beam comes in a one metre long inch-wide white PVC tube, pre-drilled with the element mounting holes and topped and tailed with soft rubber caps. Uncap your tube, and out come four elements - one director, one reflector and two driven. These slide through the mounting holes: a clip on the element stops it at the right place and you then slide on an O-ring from the other side to finish. The kit also includes five metres of stranded-core RG-58 with a BNC at one end and croc clips on the other. Even including adding the element end caps -- to prevent passing pigeons from getting their eyes poked out, I suppose -- you'd be hard pressed to take more than two minutes to get everything connected. It takes a bit longer the first time, as the holes are slightly too small for the elements and you need to give it some welly in sliding them in, with a slight risk of bending the elements if you're not careful (I wasn't. They're OK now). After a few assemblings and disassemblings, they become a lot looser and you'll need the O-rings. They're tiny. Don't lose them. You probably will, so SOTA Beams includes a couple of spares.
All that's fine, but you'd look a bit of a kipper standing there on top of a mountain holding up the beam. So you can get a SOTA Pole - actually a Shakespeare fishing pole - which has 6.7 metres of carbon fibre telescoping up into the wide blue wotsit. The beam itself has two mounting brackets, one horizontal and one vertical, and the beam sits around four metres up the pole. The kit also includes three guy ropes, three ground pegs and a guy ring: once you've got everything knotted together (a one-off job taking about five minutes even if you're - pardon the expression - ham-fisted) it's done.
After a test assembly in the front room, I and my teenage son took the SOTA Beam and pole up to Hampstead Heath, a large open space in North London noted for its wide variety of recreational activities. I didn't time myself, but even given much traditional father-son badinage it was five minutes from picking our spot to getting the beam in the air. Having a spare pair of hands helps, but is by no means necessary.
I got an SWR of about 1.3:1 at 144.3 MHz -- there's no adjustment possible -- and although I was a bit chary about using croc clips, they do a perfectly good job. In an antenna designed to be rebuilt every time you use it, weatherproofing isn't really a factor -- sensibly, though, the clip end of the coax is sealed with glue.
Conditions were dead flat on my first trial, so I just made some local contacts. They seemed to bear out the claimed 12 dBi gain when I dropped the power on my FT-817 to 500mW and swung the beam around using my integrated Armstrong rotator. As an experiment, I also ran a wire from the top of the pole at 45 degrees down to my Z11 autotuner and had a pop at 40, 20 and 15m. Not very successful, but with the higher bands very quiet and the lower ones stuffed full of contest hounds I wasn't motivated to try for too long. As a skyhook to get your HF wire up away from the muck, it's mechanically fine and I expect to be running both VHF and HF as a matter of course when I go out to play.
The beam is rated at ten watts max. I had a 30 watt linear with me and of course couldn't resist: there were no problems, but perhaps I'd be happier with a slightly more robust connection method on the driven elements before doing much of this. The combo of 30 watts, DYC-817 compressor, this beam and my '817 should be a very potent portable station when conditions are hot and I'm somewhere exotic: I very much look forward to finding out, as it'll be perfectly feasible to backpack this via low-cost airlines for one-man DXpeditioning on a very reasonable budget.
Teardown was also painless, as was strapping the beam and the pole to the backpack. When you're lugging around a rig, tuner, compressor, cables, gel cell and a refreshing beverage, the extra 800g of the pole and 200-odd g of the beam is neither here nor there.
I'm very happy with this product: it does what it claims, and is clearly the result of many, many hours experience at the sharp and soggy end of portable operations. The price may seem a bit steep, and you could easily build something similar out of coat-hanger wire, bamboo and plumber's tape -- I have done so myself -- but the whole ensemble is so neat and convenient that I don't begrudge a penny of it. I haven't mentioned the instructions because they did their job too: they're short, sweet and complete, even including knot-tying instructions for the guy rope.
One unexpected extra. In the three hours or so I spent on top of Parliament Hill among the kite-flyers, dog-walkers and other strolling players, I had five people come up to me and ask "What on earth are you doing?". I've probably done more PR for amateur radio in those three hours than I have in years sitting in the shack, and that feels good.
You can buy the beam and/or poles in a number of combinations, and I recommend you check out the website for these. The price given here is my rough dollar conversion of the retail price sans postage and packing from the UK: I don't know if SOTA Beams is set up for shipping abroad, so you should talk to them if you want to know.
Looking forward to lots of on-air rambling...
Rupert Goodwins, G6HVY |