Turning on a transmitter is almost like daring the authorities to come knocking. The simple act of being on the air in the first place is illegal; broadcasting without a license is one of the only crimes where the perpetrator boldly announces they're defying authority while they commit the offense.
Outside of the rule-breaking aspect, being on the air is simply fun. There is no other thrill quite like the one you get from "pirate" broadcasting. Trust me - you will know it when you feel it.
Unfortunately, the fun only lasts as long as it takes the authorities to find you. Eventually, they will. Sometimes, they'll take little or no action. But in the majority of cases, they'll shut you down in the end.
That is why any free radio broadcaster should always set up shop with the thought that, one day, the fun's going to stop. However, you can influence just how long it takes for the radio cops to take action.
To help get a jump start on a long station life, here are some tips of the trade:
Have a clean signal.
The quickest way to get the authorities sniffing your tail is to sloppily throw together a homebrew transmitter and use a coat hanger for an antenna. There's the potential for interfering with anything from aircraft radios to the neighbor's television. Both will call somebody to do something about it.
When planning out a free radio station, choose the frequency you plan to use wisely. There are some excellent tools which can help you figure out which part of whatever band you're working on works best. Stay as far away from local stations as possible - interfering with them, intentionally or not, will bring goons to your studio after a broadcast or two.
If you're going to build your own gear, take your time. Check the air chain for interference potential, especially after hooking it up to the antenna. Conduct short test broadcasts before you begin full-time programming.
If you can afford it, either buy "plug and play" equipment or find someone who can assemble a transmitter kit for you. Attach filters between your transmitter and antenna - they are an excellent barrier to any interference that might otherwise squeak by, and should be used on any transmitter.
Before every broadcast, double-check the gear. Make sure power levels are adequate, connections are tight (especially between the transmitter and antenna), and the system is stable. Some transmitters have been known to drift out of tune, which can be deadly - especially if you step on a legal station's signal.
If you have the resources and technical expertise, consider either broadcasting on the go or putting your transmitter in a different location from your studio. Both involve technical challenges that make it a bit harder to broadcast, but they provide excellent defense against contact with the radio police.
Remote stations involve a studio-to-transmitter (STL) link. This keeps you one step ahead of the bad guys, because they will usually track a pirate station down by homing in on its transmitter's signal.
If your transmitter goes off the air in the middle of a broadcast, it's the surest sign of warning that the radio cops are close by. Often times, when authorities seize stations' equipment, they'll take anything even remotely related to broadcasting.
If your transmitter's right with you in the studio, that means they can take your microphone, mixer, CD players - even the CDs you might have been playing. If you only lose the transmitter and antenna, because they're sited away from the studio, the pain isn't so bad.
Mobile stations are the most technically challenging, but they're also the toughest to bust. It's harder to hit a moving target.
The downside to mobile broadcasting is keeping your signal stable - a vehicle is not as sturdy as a house. It's also tougher on the power system: the electric company is mostly there all the time, while a car battery has a much shorter lifespan, and running adequate levels of power may take more than the vehicle itself can provide, which necessitates secondary power sources (like extra batteries, a generator, etc.).
Choose the programming wisely.
If people won't listen to you, why go on the air in the first place? Will you be covering local government, running talk shows off a satellite, or playing an underrepresented form of music? Remember, you are using a public property - in return, you're supposed to give something back.
Most radio enforcers are thinly spread out, responsible for a large geographic area. The farther the drive from their office, the less chance of being monitored by the authorities. If you can keep them guessing and avoid their ears, it'll take longer before they find you.
The longer you stay on the air, the more chance there is that someone will hear you. Not all of your listeners may be friendly. It may be a good idea to vary your broadcast schedule and the lengths of each broadcast.
Going on the air just to hear yourself talk is a terrible idea. So is not paying attention to anything else you broadcast. Freedom of speech issues aside - remember that anyone who's within listening range can hear you, and some of those people might not like you being there: what would the grandma down the street do if she heard your station?
Put work into your performance. Practice before you flip the switch. This doesn't mean mimicking the other stations in town, but it does mean keeping things moving.
Radio is a fluid medium. You hear something one second, but it's gone the next. Long periods of silence or technical difficulties with your broadcast will drive listeners to find something else.
If people like what they hear, you build community support - and strong support from your listeners can help in an impending battle with the authorities. It will also have a great influence on what to do next when contact does come - allies are a good thing to have.