Harnessing the Airwaves A Pirate Radio Primer (Winter, 2001-2002) ----------------------------------------------------------------- By Mark12085 This article is in no way condoning the practice of illegal radio broadcasting. Read on at your own risk.... Let me start off by letting you know that this article alone will not get you on your merry way to the airwaves. Radio, especially unlicensed low-power transmitting, is a complicated subject. Please do some research and plan wisely. The airwaves are for everyone to use, so don't abuse them. Arr Ye Matey The phrase "pirate radio" seems to strike fear in the public. Seems like pirate radio has always had a connotation of brute guerillas seizing national airwaves and replacing it with propaganda. That couldn't be any further from the truth. Pirate radio is simply transmitting radio frequency energy through the air at low power minuscule compared to the licensed stations spewing kilowatts of power from antenna towers. Unfortunately the Federal Communications Commission seems to believe that they own our air, therefore anyone who does not have a spare $10,000 floating around to go through the licensing process must be raided. Too bad for them, because air is free. A Heart of Gold The heart of any station is the transmitter. FM oscillator, broadcaster, exciter they are all the same thing, just different names. Basically, there are two types of transmitters available: VCO and PLL. VCO, voltage controller oscillator, is just that: an RF oscillator controlled by the voltage. While cheaper (around $50 for one-watt models), it will drift off the frequency it is set to transmit on as voltages, temperature, and settings change. That means if you set it to broadcast at 100.0MHz, you may find it transmitting at 101.2 an hour later. PLL (phase-locked loop) transmitters, while a bit more costly (roughly $40 more than VCO), are a much better deal. They are controlled via microcontrollers, which means they will never drift off frequency. Most transmitters come in two types: mono or stereo. While a stereo transmitter is slightly more expensive, it is still more economical and space-saving than adding a stereo encoder to a mono setup. Think before you buy about which setup would be right for you. While great for broadcasting around the house, simple transistor or BA1404 chip based transmitters are not sufficient for professional grade radio. They were designed specifically for short-distance broadcasting, so let them do their appropriate job. Transmitters can be purchased ready-built or in kit form. Kits usually include the PCB, parts, and instructions. Do not attempt a kit unless you are truly experienced with soldering SMD parts and RF emitting devices. PCS Electronics and NRG Kitz both carry high-quality transmitters of varied outputs. Power to the People A transmitter would be useless if it had nothing to run on. Most transmitters require a power source. PCS Electronics makes a computer card transmitter that plugs into a free ISA or PCI slot, so that would be an exception. A plug-in "wallwart" transformer is not a sufficient power source. Remember, the quality of the power determines the quality of the transmission. You will need a well-regulated, well-filtered power supply, like the ones designed for CB and ham radios. (RadioSlack sells one for about $30.) A 12-volt car battery will also work. Just be sure to keep it maintained. Spread the Love Although it may not seem like it, the antenna is the most vital part of a station. A 1-watt station with a well-built antenna can easily supersede a 25-watt station with a craptenna. The easiest and most common antenna is the dipole, which is basically two wires going out in opposite directions cut according to the frequency you are transmitting on. There are loads of other great antennas that are easy to build, such as the ground plane, J-pole, slim jim, and on and on. I will not go into detail about building the perfect antenna because there are tons of sites devoted only to antennas (check out the list later on) and books on the same subject. Most antennas are either omnidirectional or directional. Omnidirectional antennas, such as the dipole and 5/8 ground plane, transmit in all directions. Directional antennas on the other hand spew RF in one direction. While we're on the topic of antennas, don't forget to invest in a good SWR (standing wave ratio) meter. The SWR measurement is probably the single most important factor in determining the effectiveness of your antenna. Although cheap SWR meters made for CB radios will work for our setup, they will be far from accurate. Try to aim for an SWR of 2:1 or lower. An SWR reading of 1.5:1 would be theoretically perfect, but realistically impossible. Putting It All Together Connecting everything together is not quite as simple as a length of RadioShrek coax. Firstly, the impedance of the coax has to match the parts you are connecting them to, usually either 50 ohm or 75 ohm. Secondly, cheap coax results in cheap connections line loss. Line loss is literally losing your transmitter energy out of the cable as heat. Line loss increases as the length of the coax increases. Therefore, use as short of a length of coax as you can. Also, use high-quality, well-shielded cable, such as Belden cable. Staying Low You don t have to be a genius to figure out the fact that unlicensed radio broadcasting at more than about 10 milliwatts is illegal. And yes, they can pinpoint your location while you are transmitting. Prevention is the key. Use your head. Ninety percent of all the pirates busted were caught because they were transmitting crap in other frequencies due to a shoddy setup. Don't forget, the aircraft band is directly above the FM band. Filters (bought or built) are strongly recommended to block out harmonics you may be transmitting. Stop transmitting if the FCC contacts you or if you see any suspicious cars circling the neighborhood. If your budget allows, look into a microwave link for your station. A microwave link allows you to operate your transmitter from a distance varying from a couple of hundred yards to miles. Now it is up to you to do your own research on what would be best for your setup. The sites listed below not only sell high-quality transmitters but contain loads of free information on your setup. You might also want to check out some books from the American Radio Relay League (ARRL). Be smart, and happy transmitting. Reference ARRL Handbook for Radio Amateurs ARRL Antenna Handbook http://www.nrgkitz.com Lots of useful info, transmitters, amps, etc. http://www.ramseyelectronics.com High-quality products if you have a fat wallet.... Greetz to: TCRams, Zero, FooGoo, ILFs, Ferntheil, APCm, and 2600.