"SCTV Network," the satirical late-night comedy series dropped last month by NBC after a two-year run, will be reborn next fall--but for an audience of a relatively select few. Cinemax, a pay TV service with 2 million subscribers on 1,600 cable systems nationwide, including Arlington's Metrocable system, announced yesterday it had picked up "SCTV" for an 18-show run to begin in October.

Cinemax is the corporate little sister--called a "tier" in the cable business--to Home Box Office, the nation's largest and most successful pay TV service; both are owned by Time Inc. "SCTV" represents the first original programming to be offered on Cinemax, which has been an all-movie channel since its inception in August 1980.

Each show in the new series will be 45 minutes long, half the length of the weekly NBC series still in reruns, and new shows will premiere every other week, a Cinemax spokesman said. Andrew Alexander, executive producer, said from New York that "SCTV" turned down an offer from Showtime, a larger pay service, because the Cinemax deal "enables us to do the show we want to do."

Alexander said the money involved was "comparable to" network fees paid for the series, which would put the 18-show package at roughly $6.5 million. The only members of the "SCTV" group whose participation he could guarantee on a regular basis are Andrea Martin, Joe Flaherty, Eugene Levy and newcomer Martin Short, but Alexander said he hoped that John Candy, Catherine O'Hara and perhaps even former cast member Harold Ramis (who cowrote "Animal House") would return from time to time.

Rick Thomas and Dave Moranis, best known to the show's cult of followers as the time-killing Mackenzie brothers, are unlikely to return, "but only because of their film commitments," Alexander said.

Bridget Potter, vice president of original programming for HBO and Cinemax, said she was "ecstatic" about the arrangement. "Cinemax made a serious commitment about a month ago to go into the original programming business," she said. "This is a terrifically intelligent way to get started. 'SCTV's' audience fits the Cinemax audience absolutely perfectly--young and hip and intelligent and incredibly sophisticated."

Cable TV generally does not suffer from restrictions of language and subject matter common in network TV. Potter said that the Cinemax version of "SCTV" will be able to parody the kinds of foreign films the troupe members weren't able to lampoon on NBC, and Alexander said the ensemble now will be able to "tackle films that could be perceived as risque'." But, Alexander said, "We don't see it is as an opportunity to run rampant or have Guy Caballero pull his pants down."

Guy Caballero, as played by Flaherty, is the president of the mythical SCTV Network, a flip-flop reflection of America's TV culture. Potter said that when the Cinemax season begins, Caballero may convert SCTV to a cable channel. Actually, Caballero already flirted with cable, in an "SCTV" parody of "The Godfather" that had him refusing to join in a cable venture called Ugazzo-Vision, a move that precipitated all-out armed warfare among the networks.

But that was only make-believe.

Alexander and NBC executives negotiated for weeks to find a way to keep "SCTV" and NBC together. NBC Entertainment president Brandon Tartikoff repeatedly refused to consider alternating episodes of "SCTV" with the network-produced "Saturday Night Live." Tartikoff's final offer, Alexander said, was a weekly "SCTV" hour in the 7 p.m. Sunday time slot opposite "60 Minutes." But by FCC decree, that hour must be devoted to informational or children's programming, and Alexander said he and his performers balked at retooling their show for the "2-to-12" age group.

A child psychologist reportedly sat in on the meeting at NBC in which the possibility was discussed and told Alexander what "SCTV" wouldn't be able to do and say at 7 o'clock on a Sunday night. Tartikoff was using "SCTV" as a pawn, Alexander says, to keep the Sunday night time period in the entertainment division's bailiwick. NBC News appears to have won the battle, however; "Monitor," the low-rated NBC News magazine program, will move to the Sunday time period in the fall.

Asked why "SCTV" ended up on Cinemax rather than the 11.5 million-subscriber HBO, Alexander said Cinemax made the more attractive showcase and Potter said "SCTV" made the ideal attraction for the new Cinemax programming initiative. "On Cinemax, 'SCTV' will be seen in prime time, as it never has been before," Potter said. "We think this will increase the audience for the show and increase the audience for Cinemax. We're in the business of making Cinemax, and HBO, a necessity."

For the 1982-83 Nielsen ratings season that ended in April, "SCTV" averaged a 3.3 rating (percentage of all TV homes) and a 16 share (percentage of TV sets in use during its time period) in its 90-minute berth on Friday nights, at 12:30 a.m. That translates into about 3 million households, 1 million more than are available through Cinemax.

Alexander said that when the Cinemax run is completed (it could be renewed or dropped after the first 18 shows), "SCTV" reruns will return to free TV. The reruns include five years' worth of half-hour syndicated shows that preceded the NBC show. He also said an "SCTV" theatrical movie, utilizing all present and former cast members, is in the works.

In panic at the thought of losing their weekly fix of cheeky, even savage satire of myriad showbiz vulgarities, a band of "SCTV" fans recently organized themselves into a grassroots "Save 'SCTV' " movement, picketing NBC studios in New York. On Friday, Alexander appeared before the inflamed throng and reassured them that "SCTV" "would continue in some form." Yesterday he said officially of the program, "It's alive."