Jerry Nachman, vice president and general manager of NBC-owned WRC for the past 13 months, shocked the station yesterday when he announced his resignation, effective immediately.

Nachman and NBC executives insisted that the resignation, while surprising, was the former's personal decision.

In a telephone conversation, Nachman added that it wasn't even "all that sudden. I told Al Jerome {president of NBC television stations division} about it three weeks ago. I've been on the fast track at NBC for six years, with four vice-presidencies. It's been nice, but I'm 41 and I'm just not sure I want to stay on the train ...

"I want to reunite myself with my intellect, with my friends, my family and with journalism. I want to see my mother and my father and sit on my exercise bike without the beeper going off. I don't know what my next move will be but whatever it is, it will be either a big surprise or no surprise" ...

Jerome announced yesterday that Nachman would be replaced immediately by Allan Horlick, who has been station manager at WMAQ, the NBC-owned station in Chicago, for the past three years. Horlick spent six years in Washington as sales manager and then sales director of WRC, before transferring to Chicago in January 1985 ...

Nachman's surprise announcement was a bombshell at WRC. The colorful, rotund and always quotable GM is credited with restoring management morale at Four after being brought in from WNBC in New York, where he had been news director, to replace GM Fred DeMarco in October of last year.

Although WRC is still struggling to catch up with WUSA in local news in the early evening race, Nachman and his personal pick as news director, Bret Marcus, had been fine-tuning the news operation, and in the November ratings book, the station -- although dogged by competition from Oprah Winfrey on Nine at 4 p.m. -- nevertheless continued to show some improvement ...

His loss at WRC will be felt keenly in the news operation. Nachman was a journalist right down to his well-hidden bone structure. He had worked in print journalism and as a radio correspondent in major markets around the country before joining NBC in 1981. At WRC he kept a close watch on day-to-day news operations ...

Horlick said yesterday he has "no plans whatsoever" to change Marcus' role. "I'm very excited about working with Bret. His excellent reputation precedes him" ...

Jerome said yesterday that after Nachman told him of his decision to quit, he and other top executives at NBC, including president Robert Wright and group executive vice president Robert Walsh, had been exploring alternatives to keep Nachman at the network, but to no avail ...

"I'm very sad about it," Jerome said in Washington. "It was a surprise to me. He's done a terrific job and I've had great admiration for the way he's run WRC. His reasons are courageous and healthy and I admire him. The station has made great strides under his leadership. We're just fortunate that Al is available as a replacement" ...

Several years ago, NBC began eliminating the position of station manager at its five owned TV stations. Only Horlick, credited with doing a good job in Chicago, remained in such a post, and Jerome said the network had been looking for some time to find the right move up for him ...

Nachman notified the WRC staff in a series of meetings yesterday morning, and both Horlick and Jerome were in town to talk to staffers ...

Nachman hinted yesterday that after getting reacquainted with his wife and family he's thinking seriously of writing again. One source at NBC said Nachman has displayed talent as a potential situation comedy writer ...

In Other News

A pair of CBS situation comedies and a tribute to a fallen Hollywood stuntman on ABC both outdrew the historic appearance of Soviet leader Mikhail Gorbachev on NBC Monday night ...

National Nielsen ratings for the 8 to 9 timeslot showed the combination of a "Kate & Allie" rerun and a fresh "Frank's Place" episode on CBS averaged a 14.8 rating and a 22 share. "The Ultimate Stuntman: A Tribute to Dar Robinson" on ABC averaged a 14.0/23 ...

"A Conversation with Mikhail S. Gorbachev" on NBC averaged a 9.9/15 (each rating point represents 886,000 TV homes) ...

NBC estimated some 15 million viewers saw the Soviet general secretary and NBC News correspondent Tom Brokaw ...

In Washington, which Mr. Gorbachev visits next week to meet with President Reagan, the interest was slightly higher. The NBC interview did an 11.0/16 on Channel 4, compared to a 20.6/30 on Channel 7 for "The Ultimate Stuntman" and a 17.4/26 for the two CBS comedies on Channel 9 (each local rating point represents some 15,851 homes) ...

NBC News vice president Tim Russert was not dismayed by the interview figures, which were about average for a news documentary. "I'd love to see the demographic profile of our audience Monday night. We're very proud of the accomplishment" ...

More importantly for NBC News, details of the interview were on the front pages of major newspapers around the globe yesterday morning ...

The program will not appear in the national rankings since it was "sustaining" (i.e., without sponsors) ...

NBC, by the way, recorded some 800 phone calls at its five owned stations after the interview, with 149 callers complaining that "ALF" had been pre-empted by the broadcast. Another 130 complained that the network was airing communist propaganda ...

WRC recorded 105 calls, including 30 complaints about the absence of "ALF" and the presence of a communist on the air ...

To placate you disappointed ALFophiles, Ad Age this week reveals that Paul Fusco, the co-creator of the NBC series (with Tom Patchett), is also the voice of old furball ...

That's been one of the best-kept secrets in the business since the series debuted two years ago. Cast members had been sworn to secrecy ...

Apparently Fusco and the network got upset when reports were published identifying at least one of the midgets who wear ALF's furry costume for some of the action scenes and decided to tell all ...

1 24.0 60 Minutes 35 CBS

2 23.4 Murder, She Wrote 33 CBS

3 22.9 The Golden Girls 39 NBC

4 21.3 Long Journey Home 34 CBS

5 20.7 Who's the Boss? 32 ABC

20.7 Growing Pains 31 ABC

7 20.2 Family Ties 28 NBC

8 19.5 Cheers 36 NBC

9 19.0 NFL 'Skins vs. Rams 33 ABC

10 18.9 227 33 NBC

18.9 ALF 29 NBC

12 18.6 The Cosby Show 37 NBC

13 18.3 Amen 32 NBC

14 18.1 Newhart 27 CBS

15 17.7 Hunter 34 NBC

17.7 My Two Dads 25 NBC

17 17.4 The Gambler III 29 CBS

18 17.1 Designing Women 26 CBS

17.1 Night Court 24 NBC

20 16.9 A Different World 33 NBC

NBC won the holiday week with a 15.1 rating and a 25 percent audience share, compared to a 13.7/23 for CBS and a 12.4/21 for ABC ...

"The Cosby Show" aired a rerun on Thanksgiving Day and finished out of the top ten for only the third time in its three years on the air ...

CBS meanwhile, won a Tuesday night for the first time this new season, which is one of the reasons the network has finally tied ABC in the season-to-date race for second place behind NBC ...

In other Major Developments last week, any one of which severely could test your faith in the future of the Republic, ABC's tribute to the 75th anniversary of Las Vegas was 25th, the Jay Leno special on NBC tied for 27th; a "This Is Your Life" special on NBC was 30th; and a special marking Rolling Stone magazine's 20th anniversary was 48th ...

On the other hand, NBC's praiseworthy "Lena: My 100 Children" tied with "Beverly Hills Buntz" for 37th, the Disney World celebrity circus on NBC tied for 41st, and "Unsolved Mysteries" on NBC was 45th ...

On still another hand, ABC's "Norman Rockwell's Breaking Home Ties" tied for 58th ... while the two-part theatrical movie "Gandhi," CBS' major effort in Uplift last week, managed to fill two spots in the Final And Almost Certainly Fatal Five Plus One ...

Part I of "Gandhi" was 65th, followed, in order, by CBS' "West 57th"; Part II of "Gandhi"; and three ABC troupers, "Pursuit of Happiness"; "Sledge Hammer!" and (mirror, mirror, on the wall, which is the lowest-rated of them all) "The Charmings," in 70th place for the week ending Nov. 29.