7:30 P.M. TIME SLOT : KTLA TO DEBUT 4 FIRST-RUN SERIES

In another step forward in the evolution of independent TV stations, KTLA Channel 5 said Tuesday that it will fill its key 7:30 p.m. time periods this fall with four new comedy series.

And when another new series joins the lineup in January, KTLA will have the distinction of featuring first-run comedy programs every weeknight, rather than the reruns of old network series that traditionally have been the staple of stations that aren’t part of the ABC, CBS or NBC networks.

KTLA General Manager Steve Bell said that Channel 5 is the first independent station in a major broadcast market to depart from tradition in this way, using a “checkerboard” of different shows each night of the week instead of “stripping” episodes of the same series into the same time slot each night.

The past nine years have seen a steady increase in the amount of original programming carried on independent stations, from daily talk shows and game shows to occasional movies and miniseries to weekly scripted series such as “Fame,” “Small Wonder” and “It’s a Living.” The growth reflects the evolving economic strength of the independents, enabling them to develop and support the sort of programs that were once considered the sole province of the networks.

Tuesday’s announcement from KTLA indicates just how much of this programming is now available. And more is coming. There also will be first-run comedy series on other stations this fall, and next spring the Fox Broadcasting Co. will launch five hours a week of first-run programming in prime time--two hours on Saturday and three on Sunday. That will be seen locally on KTTV Channel 11.

KTLA’s 7:30 p.m. weekday lineup, starting Sept. 22, will be:

Monday--Reruns of “Square Pegs,” a comedy about high school students that ran on CBS during the 1982-83 season. This will be replaced in January by new episodes of “Charles in Charge,” with Scott Baio reprising the role he played when the series ran on CBS during the 1984-85 season.

Tuesday--”The New Gidget,” a spinoff of the syndicated TV movie that cast Caryn Richman as a grown-up Gidget coping with life in the ‘80s, with Dean Butler as Moondoggie.

Wednesday--”What a Country,” a comedy about a diverse group of immigrants adapting to life in the United States, with Soviet comedian Yakov Smirnoff playing one of them.

Thursday--”One Big Family,” a multigenerational family comedy starring Danny Thomas.

Friday--”What’s Happening Now,” a revival of the 1976-79 ABC comedy that premiered in syndication last season and continues for a second year.

Also new to KTLA’s weekday schedule this fall will be reruns of “Falcon Crest” at 2 p.m., reruns of “Magnum, P.I.” at 6 p.m. and reruns of “Silver Spoons” at 7 p.m. Twenty-four new episodes of the latter comedy series are being produced but won’t be broadcast here until after the first of the year, Bell said.

The first-run comedies will be produced with budgets similar to those of network shows, Bell said. This is possible, he explained, because the stations running them have committed to broadcast two years worth of episodes and because the producers and distributors are retaining several commercial slots in each show to sell themselves.