A 2.75-million-watt television transmitter planned for Fairfax County could disrupt public safety communication signals throughout the Washington region, placing area residents at risk, police and fire officials said yesterday.

If approved and licensed by the Federal Communications Commission, the transmitter would operate on the 470-megahertz frequency. Officials said the TV station could overpower the area's emergency medical and public safety signals, which are much weaker and are on neighboring radio frequencies.

The transmitter is planned by Urban Broadcasting Corp. The District-based firm plans to operate a new local station on Channel 14 that will emphasize home shopping and other local programs.

Public safety officials said the transmitter would be near Routes 29 and 211 in Merrifield, less than two miles from Fairfax Hospital and within three miles of similar sites for Fairfax County police, fire and rescue communications.

In addition, officials say that because the channel's broadcast range will include most of the Washington metropolitan area, most, if not all, public safety communication systems could be adversely affected.

"We don't want to be in a position where we have an ambulance en route to a hospital . . . and lose voice communication with the hospital," said Thomas P. Rametta, public safety staff member of Metropolitan Washington Council of Governments.

However, company officials, who said they hope to see the station operating in two or three months, maintain that such problems will be addressed before licensing.

"We are comfortable that this can be built and will not interfere with any public safety communications," said John Feore, a consultant for with Urban Broadcasting Corp.

William C. King, one of two engineers hired by Urban Broadcasting Corp. to address technical questions, said the firm believes that an elaborate and expensive filtering system will resolve any problems. The concerns "can be addressed and will be addressed," King said. "We will make sure it has limited, if any, out-of-band radiation."

Area public safety officials say they have been given assurances, but they are not satisfied. "We are not confident with what has been brought forward so far," said Fairfax County Police Chief John Granfield. "This {station} will be transmitting with quite a lot of wattage and it's quite close to our channels . . . . There is too much at risk."

In response to concerns raised by the fire and police chiefs, the Metropolitan Council of Governments board of directors voted unanimously yesterday to urge the FCC to assign a different transmitting frequency to Channel 14. The board also asked the FCC to interrupt the signal immediately if it interferes with public safety.

FCC officials, when contacted yesterday, expressed hope that potential problems could be addressed with technology, because finding a vacant frequency in an already crowded urban broadcasting market is difficult.

Urban Broadcasting has applied for and received a construction permit from the FCC. According to Pendarvis, once the construction is completed, the company is required to file for a license before it can begin transmission.