It was bad enough uhen two fire department radios-- one valued at $2,000-- were stolen from two Fairfax County firehouses.

It was worse when fire department communications channels began cracking with epithets of derision-- "jive . . . turkeys"-- and with false reports of fires, auto accidents and equipment failures.

While there may be an amusing side to some of the clearly amateurish announcements that have been coming over the air since the radios were taken, the thefts could also mean trouble, firemen say.

"We'll sit here and laugh about it, but if it comes to the point that there's a fire or somebody has a heart attack and you can't understand the dispatcher, that's going to cause a delay in response," said Sgt. James Lawson of the McLean station.

One of the few clues firemen have to their annoying on the air adversaries is the name at least one of them uses to identify himself-- "The Green Hornet."

"The names we call him, you can't put in the newspaper, one fire official said yesterday.

While all of the harassing calls are sometimes referred to under the heading of Green Hornet broadcastsm authorities say they believe there are at least two sources for the broadcasts.

One night about two weeks ago a fireman's portable walkie-talkie vanished from a battery recharger at the McLean station on Chain Bridge Road while firemen were answering a call.

That was when one set of spurious calls began. They sounded like this: "Wagon 27, Wagon 27-- my pump has broken down. Send another pump." And like this: "Unit 8 calling, unit 8 calling-- send company 29 to fire at Zayre's."

One day early this week a six channel radio valued at about $2,000 was snatched, apparently by children, from an ambulance seat at the Dunn Loring station near Tysons Corner.

After that incident the airways crackled with children's voices and mocking epithets.

Firemen say they were not misled by the false calls, recognizing the absence of proper terminology. But concerned about interference with legitimate calls, they have been trying to track down the impostors.

Once they invited the Hornet to what they said would be an unoccupied fire house to recharge his radio, warning him that the batteries were about to die. Nobody came.

Eventually, officials say, the batteries in the stolen radio will run down. In the meantime, they have improved security at the firehouses -- and are waiting for the next call from the Green Hornet.