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Bicycle Portable Operation Until a few years ago, most portable operation involving hand-carried (or back-packed) equipment was limited to carrying a VHF/UHF 'walkie-talkie' to a local hill-top. But the growing interest in constructing effective and compact HF QRP rigs – both scratch-built, and from kits – plus the availability of commercial HF 'handheld' equipment, means that HF back-packing has become a popular way for amateur radio operators to spend a day in the countryside. Indeed, it is this ready availability of portable equipment (as well as light-weight fibre-glass antenna supports) that means it's never been easier for those who enjoy 'adventure radio', to seek out interesting places from which to operate their portable radio equipment.
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Why
'bicycle portable'? In my case, there are plenty of potential sites within cycling distance of my home in Chepstow, south-east Wales. A comfortable cycling range for me is about 15 km (a round trip of 30 km). But even this limited radial distance takes in large stretches of the beautiful Wye Valley; the local 'Summits on the Air' (SOTA) high point at Wentwood Hill; the unique Gwent Levels; and the scenic villages and open countryside to the north of Bristol. But I don’t think that my location is particularly unique – I suspect that most UK amateurs can think of several potential ‘stroke-portable’ locations within a 15 km radius of home.
There is a certain sense of achievement to be gained when transporting all the essential items of radio equipment; provisions; and safety equipment by ‘pedal power’ alone. Apart from anything else, the more leisurely pace of touring by bike enables a much better appreciation of what’s around you than other forms of transport. So, for me, one of the main attractions of going bicycle portable (if only for these brief periods) is to do something that does not involve travelling by that most damaging method of transportation: the motor car. Of course, cycling is a great way of keeping fit too! I am advised that, for most people, cycling is kinder on the knees and hips than other form of exercise, such as road running. Of course, if you're in any doubt about your own health, it would be worth consulting your doctor before commencing any form of strenuous activity, such as cycling. In any event, if you haven’t cycled for many years, I would suggest starting off by first doing several short cycling trips – each of, say, ten minutes duration. Then, gradually increase the duration (and the payload) until you feel confident that you can undertake – and enjoy – your first bicycle portable operation. Don’t forget that, on a cool day, you’ll need to wear more layers while operating than you’ll be wearing while cycling. It would be a shame if you had to return home early merely because you didn’t pack that extra sweater! What bands? Most bicycle portable activity takes place during the day, so you'll need to prepare for operation on bands that are likely to provide a reasonable chance of making some contacts during the hours of daylight. For example, the lack of daytime ionospheric propagation on the lower frequencies may make 80 m a poor choice. Even though 160 m suffers from the same problem, a special operation using, say, a kite-supported vertical wire, might generate enough local interest to make the operation worthwhile – especially if the outing is announced beforehand at the local radio club. What antennas? But most of my trips have involved using the bike frame itself as a support. After first guying the bike in an upright position using two short guy ropes from the seat tube, I then tie an extended telescopic mast to both the bottom bracket and the crossbar of the bike. A couple of layers of ‘bubble-wrap’ around the bike tubes helps to protect the paintwork from damage; and the added friction introduced by the bubble-wrap helps to keep the mast firmly in position.
For LF/MF/HF operation, the obvious choice is a wire antenna in the form of either a vertical; end fed wire; or centre-fed doublet. After carrying out early experiments using vertical and end-fed antennas, I now prefer to use balanced antennas for 10 – 80 m because they don’t rely on a good RF earth for effective, predictable results. A resonant dipole, 50 ohm twin feeder, and balun work well together. However, my favourite antenna (for both single-band and multi-band expeditions) consists of an inverted-V centre-fed doublet; a balanced feeder (using lightweight speaker cable); a switchable 1:1/4:1 balun; and an antenna matching unit. Most lightweight telescopic poles and short masts can be transported by being tied to the crossbar of the bike. Although all the equipment and batteries can be carried in a back-pack, this is far from ideal. The better – and much safer option – is to fit a rear rack to the bike, and use panniers for the heavy items. If I still need to take a back-pack, I use it for carrying lighter items only – such as water-proof clothing. Other antenna options worth trying on the lower frequencies include kite-supported antennas. For an RF earth, you can try using crocodile clips to connect the ATU earth-point to nearby fence wires. Note that running out your own ground wires can take a surprisingly long time, and such wires may present a safety hazard to you and to passers-by. Also, keep in mind the safety considerations when using kite antennas. Apart from the obvious need to ensure that such antennas do not come into contact with other structures/power lines, it is also important to ensure that the antenna does not break free, and add to the litter which already spoils our countryside and coast-lines. Please remember: what goes up, eventually comes down. In all cases you should aim to leave your chosen location ‘as found’ – ensure that all odd pieces of tape; string; wire; and other rubbish are securely stowed away for the return journey. Leave only your footprints and tyre marks behind. What to pack? Other added luxuries might include: a fold-up stool/chair; compass; GPS receiver. Touring is almost always safer (and much more pleasurable) if you have a companion. If you can’t persuade someone to join you on your adventure, you might wish to take along a mobile ‘phone in case of emergency. Where to operate? To operate for more than a few tens of minutes, establishing a comfortable operating position is very important – especially when operating CW. On my very first outing, I was lucky enough to find some large logs to sit on. After guying the bike in an upright position near one of the logs, I then fitted my home-made plinth to the top of the rear rack (to act as the ‘operating desk’). The Elecraft K2 transceiver; ATU; SWR bridge; and the morse key were then mounted on the plinth. The resulting sitting position was so comfortable that, during the many fine contacts made that day, the old expression ‘armchair copy’ really did seem to be quite appropriate! From other locations, I have also used tree stumps, and upturned plastic buckets as seats. For me, using almost any kind of seat, together with an elevated morse key is far more comfortable than trying to operate CW with everything at ground level. When choosing a site, I look for a spot without road noise, and well away from power lines. On cool days, try to select a site having some shelter from the wind; on very sunny days, a shady spot will reduce the risk of sun burn, and make it easier to see the front panel displays. Be sure to ask permission from the landowner before setting up your station on private property. Results Following one such contact, Guy F9XN wrote on his QSL card: "Well, since I began hamming in 1948, I have never before had a QSO with a bicycle portable station . . . and I am 72! MNI TKS for a big First. Nice signal from your QRP 5W" The results while operating portable will be limited only by the prevailing propagation conditions, and by your own ingenuity. There is much scope for improving antennas and equipment, and for refining techniques for stowing the equipment on the bike; setting up the portable station; and establishing a comfortable operating position. Above all, have fun – and enjoy the countryside. More information Both the ARRL and RSGB publish a range of books covering antenna design and construction. Designs for compact transmitters; receivers; antennas; and antenna matching units are published frequently in SPRAT, the quarterly journal of the G-QRP Club.
Steve Rawlings, GW4ALG |
