One of the men behind an infamous Birmingham pirate radio station has been fined by Birmingham magistrates.

Ernest Uriah Griffiths was convicted of two charges of unauthorised broadcasting and sentenced to pay a £300 fine and £200 court costs.

Mr Griffiths was involved in the broadcast of pirate station Hot 92 FM from Hockley in Birmingham.

But the station was shut down and £4,000 of equipment seized after broadcast regulator Ofcom raided the premises in December 2006, arresting two people.

The station is one of a number of pirate radio stations operating in the city.

Mike Bothma, Ofcom's field operations Birmingham manager, said: "Ofcom takes swift and firm action against illegal broadcasting which causes serious interference to key safety-of-life services, such as the fire brigade, as well legitimate broadcasters.

"Gaining a criminal conviction against an offender is a significant development in Ofcom's fight to protect citizens and consumers from this dangerous and anti-social crime.

"This conviction against a persistent offender in Birmingham sends a strong and clear message that Ofcom takes the issue of illegal broadcasting extremely seriously."

According to research by Ofcom, there are currently around 150 pirate radio stations operating in the UK at any one time, with most stations broadcasting out of London and Birmingham.

Set-up costs are minimal. A transmitter costs around £350 and a good-quality studio can be assembled for £2,000.

The broadcaster will then identify a slot in the FM broadcasting band, locate a transmitter on high ground - usually on the roof of a local authority building such as a residential tower block.

To feed the transmitter, the illegal broadcaster will tap into the building's power supply, often by diverting electricity from the lift motor room putting the lift out of action The transmitters are usually located miles away from the studio of the illegal radio station which is linked via a wireless connection.

Despite many believing that pirate radio stations operate purely for the love of music, Ofcom claims many seek to profit from their broadcasts. Revenues come from DJs who pay to broadcast on illegal radio stations in an attempt to gain public exposure, the regulator said.

Pirate stations also make money by selling advertising, often publicising events at nightclubs.

A large illegal radio station can generate up to £5,000 a week in cash, Ofcom claims.

In 2005, the regulator carried out six raids on studios in Birmingham as part of Operation Clavichord. The action lead to the arrest of three people and the seizure of ten transmitters.

Two of the stations close in the raid had been linked to spreading the rumour that a teenager had been raped in a shop, which sparked riots in Lozells.

Another had been responsible for knocking out half of West Midlands Fire Service's radio communications during one night, Ofcom claimed.

Despite the recent rise of in the number of new, legal digital and FM stations entering the market, pirate stations continue to have a committed following.

According to research by Ofcom, 16 per cent of adults admit listening to illegal broadcasts because the stations offer access to the local urban music scene, develop grass roots talent and represent minority ethnic groups.

The research adds that pirate stations use the web to widen their audience.