At the moment FM broadcasting, with all its advantages, is the favourite for pirates. But it's well worth pointing out that in 1985 at least 25% of radio receivers in Britain can't even receive FM, so you can't pick up most pirates on older radios. Another thing, in some hilly areas FM broadcasts have a very bad coverage area. And a third advantage, you can cover a very much bigger area on MW, at least potentially. MW can be the best choice for you, especially if you're in a country area, or in hills or mountains, or only want to broadcast by day and aren't too worried about sound quality. MW transmitters are also fairly cheap and easy to build, and because you use a crystal there's no problem with tuning or with "sprogs". Though the antenna is a huge length it's just a roll of wire, and doesn't necessarily have to be up high, which gives you a quite different, if still limited, range of possible broadcasting sites. MW works by bouncing radio waves back off the stratosphere, not by line of sight like FM.
Of course there's lots of other disadvantages, one is sound quality, and stereo is out of the question, and there's not much free space on the wave band, chiefly because of a host European stations, which become stronger at night, blotting your relatively weak signal (this is due to atmospheric changes we are told). The TX is also bigger and heavier (about 12" x 8" x 6") and you'll probably need to use car batteries. One thing I forgot, if you want to reach any of the 50000 prisoners in British jails, you must use MW, FM is still banned in prison, for some typically petty reason. It is also agreed that you're generally less likely to get busted. In the present repressive climate that's well worth considering.
Enough general talk. So you want to broadcast on MW. So here's how to do it. First your transmitter. Medium Wave transmitters aren't so hard to build, any good amateur radio buff could do it, and there's people around who will build them (reckon to spend £100 to £150 [1984 prices]). The technology is tried and tested and our design is as good as any. The TX is valve operated and you use a crystal (which you have to order on the chosen wave length) which keeps you on frequency without the problems of FM. So you have to decide from the start which frequency you're going for and stick to it, or buy a new crystal. When choosing your frequency remember that it must be divisible by 9... MW frequencies are separated by 9 KHz by international treaty. If your signal doesn't conform you'll probably have the DTI and police down on you faster. If you have problems getting a MW transmitter you may be able to buy a kit or adapt an amateur radio transmitter.
I'm not exactly an expert on this and the following info comes from the US. Apparently you can easily buy second hand radio ham transmitters and adapt them. The best to go for is the Viking Valiant (200 watt) or the Viking Ranger (75 watt), both made by Johnson & Co. These ham radios are well built, have excellent audio and moreover have built in VFO's (variable frequency oscillators) which make them simple to modify to work on the top end of the AM band. All you need to do the RF (radio frequency) circuits is to add capacitance to the 160 metre tuned circuits. And all you must do to the audio circuits is to bypass the first pre-amp (assuming you're using a line level instead of a mike level). One other thing, you must bypass the speech frequency filter, which is located between the 2nd pre-amp and the driver.
When buying such a 2nd hand ham transmitter:
Security precautions and preparation are the same as for FM. But there the similarity ends. For a start your total aerial length is 1/4 your wavelength, so if your wavelength was for instance 200 metres, your aerial would be 50 metres long! You use a ordinary thin single strand wire. Buy a roll, keep it on the roll and measure it out, metre by metre. Ideally the aerial would point straight up, but that's just not feasible, unless you hang it out from the side of a tower block or a steeple, or suspend it from a balloon (only the balloon blows away). The normal method is the 'dogleg' which works just fine. The ideal site is a field, or deserted common land, far away from houses, with two tall trees (only 2 if possible, poplars are best) about 30 to 40 metres apart. Now string the 'dogleg' between the trees and down to your TX without touching branches or leaves. Sounds impossible? If you have a trained monkey that's just fine. Otherwise try our method. Practice and patience is necessary.
Sample list of things you need for Medium Wave
|
Bring along with you a catapult, a long reel of 70 lb. strength fishing line, a plenty of lead fishing weights (not too heavy for the catapult). Also some small plastic rings (cut out lids of plastic containers work fine).
Tie one end of the fishing line to a lead weight, leaving the line coiled neatly and loosely on a piece of bare ground. Then fore the lead weight from the catapult right over the centre of a tree! Go and search for it (don't try this at night). Tie on your plastic ring in place of the weight and pass about 30 metre of your aerial wire through the ring. Now get your mate to pull the other end of the fishing line, if it doesn't get tangled pull it till the ring is about 5 metres from the tree top. Tie the fishing line securely (to the tree), cut it, and head for the second tree. Repeat the performance, firing right over the tree from the far side. Pull the aerial end through, and this time tie it to the ring. Pull up as before to about 5 m from the top and tie the line. Now back to the roll of aerial wire (extended with fishing line as necessary) and start pulling it in till it's suspended without touching the trees! It's hard to get it just right so the aerial reaches your TX and is tight, adjust fishing line lengths and / or position of TX. Better choose two trees too far apart than too close.
When you finally get it all set it's hardly worth taking it down again after the broadcast, though you should loosen it off or it'll snap in the wind. Disguise it if possible. A further problem can be with kids and passers by, disguise your actions, bringing along fishing rods or a kite is a good ploy. One of the best broadcast sites is a clearing in a large wood. On Medium Wave remember, you can go right outside the city and still cover it and lots more besides.
The transmitter should be on wet ground. If it's dry, wet it. Mud is good stuff. The aerial wire should be taut all the way. Bushes are an advantage, for concealment, but don't let any touch the aerial. Your power supply is a 12 volt car battery. Bring two, well charged up, if you're broadcasting for more than few hours, medium wave uses a lots of power. If your TX is on mains (240 VAC) you'll have to get it adapted using a 'rotary inverter', it's not difficult. A lorry battery is the real thing, but what a drag to carry! If there's a chance to go on mains, by running a line from somewhere, you should go for it. Otherwise wear old clothes and gloves against acid spills.
When choosing your site balance the need for remoteness with the problems of moving the gear. The transmitter must be very well earthed, the earth is an essential part of the aerial system. Use a ring of metal stakes (e.g. tent stakes) and file off any rust or dirt for good connections. Attach the stakes securely to the chassis of your TX, with the thick metal straps or wires held by butterfly nuts or strong clean battery clips. So far so good. The cassette player, on the contrary, should be off the ground, on a box or whatever. As usual keep the audio lead, battery leads and aerial wire as far apart as possible. The cassette player is normally powered by a 6 volt motor bike battery, with suitable leads. Torch batteries are dear and have a pathetic lifespan.
Connect up your batteries, load up your cassette player with a 'trial tape' and you're ready to go.
If you've done all the above you should be broadcasting loud and clear. If your signal is still wretched chances are something is blown. Then go home. If all is well, switch off and await the time of your programme is due to start. Don't detach aerial wire with the TX still turned on.
When you're finished, switch off immediately. Then disconnect everything and pack into holdalls or large plastic bag. Be especially careful carrying the TX with it delicate valves. You should have several sites, and switch as often as you can. Don't re-use a site after an attempted bust. If you have a good dry safe stash and are coming back best leave your transmitter, cassette deck and leads there, and just take the batteries back for recharging. Such a stash should be in cover, be quite sure a hidden watcher or bod with binoculars couldn't spot you stashing the gear. It's likely that the DTI will send in men to sneak up and watch you, prior to planning a bust, so be careful, even when not on air, don't relax till safely home.
Read the FM section How to get away with it. A lot of those precautions also apply. At a MW site your chances should be much better, you need on person just to stay near the TX, in case of kids, passers by etc. and to grab or hide it fast when they get the danger signal. On many sites you can work out lookout points to give plenty of warning. However you might as well abandon the batteries, and certainly the aerial, if you have to run far.
If you have transport or good escape routes you can try a clean getaway, but safer method is to hide the gear well (not too close to the aerial if it's left up) and beat it. We favour bunkers, holes pre-dug and lined with waterproofs, under rocks, with heavy lids covered with earth and bushes. In theory they could find these with dogs or metal detectors, but we've never heard of them succeeding or even trying (you could always bury bits of metal all over the place). The possibilities are unlimited, if you're on the ball there's no reason they should get the gear... and without that they have a lousy case against you.
Top of this Page
How to be a FM Radio Pirate
How to be a Radio Pirate Home Page
Introduction to Pirate Radio
Electronics