"Captain Midnight," the electronic interloper who startled Home Box Office -- and many of its viewers -- by briefly interrupting the pay TV network's satellite signal, has been apprehended.

The Federal Communications Commission announced yesterday that John R. MacDougall, a 25-year-old satellite dish dealer and electronics engineer in Ocala, Fla., had confessed to being Captain Midnight and to violating an FCC statute against "broadcasting without a license" when he managed briefly to override the movie HBO was sending its paying customers on April 27 ("The Falcon and the Snowman") and replace it with this printed on-screen message:

"Good evening, HBO, from Captain Midnight. $12.95 a month? No way! Showtime/The Movie Channel, beware."

The message was meant as a protest against HBO's decision to scramble its signal so that it can only be intelligibly received with an expensive decoder. The $12.95 referred to the fee HBO charges home satellite dish owners to receive the signal once a descrambler has been purchased.

MacDougall, who was identified as a part-time employe of the Central Florida Teleport uplink station as well as the owner of his own home dish business, surrendered to the U.S. attorney's office at the U.S. District Court in Jacksonville yesterday after being subpoenaed by a grand jury. Accompanied by his lawyer, John M. Green Jr., MacDougall pleaded guilty to the charges after reaching a plea agreement with the prosecutor.

Instead of a maximum possible $100,000 fine and one-year jail sentence, MacDougall will be fined $5,000 and placed on one-year unsupervised probation, according to the agreement. An FCC spokesman here said the commission will abide by the agreement reached with the attorney's office and not seek stiffer punishment.

Larry Clance, attorney-adviser with the FCC's field operations bureau, said from Jacksonville that while the FCC made exhaustive efforts to locate Captain Midnight, a more severe sentence would not be justified.

"We don't think he's being let off easy at all," Clance said. "He's not a hardened criminal or a repeat offender. A $5,000 fine is substantial. He is not a wealthy person." Indeed, Clance said, MacDougall had been despondent over "financial losses" incurred by his MacDougall Electronics firm. The satellite dish industry suffered a severe recession earlier this spring when HBO and other services began scrambling their signals.

From New York, HBO Chairman Michael Fuchs said of MacDougall, "Yes, we are glad he got caught. I think the FCC was quite diligent in tracking him down. What got lost in all this is the enormous danger of what was going on up there. Those are enormously expensive pieces of real estate," Fuchs said, referring to the communications satellites that beam TV signals back to Earth.

Fuchs said "certain precautions" have been taken to make it easier to identify any aspiring Captain Midnights of the future who attempt to jam a satellite, that a proposed FCC rule would require encoding of all transmissions so they could be traced, and that "the next generation of satellites" will be more tamper resistant than those currently in orbit.

Richard Acello, editor of Satellite TV Week, a magazine that serves the home dish industry, said from Fortuna, Calif., that Captain Midnight never quite achieved the folk-hero status among dish owners that some predicted for him. "He didn't have any No. 1 records written about him or anything like that, and that's always an indication," Acello said.

"The whole event was misunderstood," said Acello. "People took Captain Midnight to be a symbol of frustration people were feeling about scrambling. It made him seem a representative of dish owners, but he was not. There was no way a dish owner could do what he did."

That Captain Midnight needed a huge transmitter and larger-than-average dish to jam the HBO signal was a clue used by the FCC in tracking him down.

According to Clance, the FCC knew it would take "at least a seven-foot dish" and a powerful transmitter. In addition, the FCC studied videotapes, supplied by HBO, of Captain Midnight's transmission to determine what kind of electronic character generator was used to spell out the message on the screen. Eventually the commission had the suspects narrowed down to "less than a dozen" uplink stations, Clance said.

A Wisconsin accountant vacationing in Ocala overheard a telephone conversation about Captain Midnight and informed the FCC, thus providing another tip-off to the region in which the signal originated. "We ran down numerous false leads" before alighting upon Central Florida Teleport and MacDougall, said Clance. "Then he realized we were zeroing in on him, and so he came forth."

MacDougall, who was arraigned yesterday and then freed on a $5,000 personal signature bond, will be sentenced Aug. 26. In addition to the fine and probation, the FCC will suspend MacDougall's ham radio license for one year, a commission spokesman said.