John Jay Iselin, the programming wizard of public TV

An intense, stimulating descendant of early American statesman John Jay has become the most influential individual in public broadcasting, outside of the newly appointed PBS president, Bruce Christiensen.

John Jay Iselin is president of the Educational Broadcasting Corporation (WNET/Channel 13, New York) and has been for the past 12 years. He presides over a station that claims to account for some 16 million to 17 million potential viewers, reaching more than 13 percent of the total PBS audience. Even more impressive, this year Mr. Iselin's station will provide over 50 percent of the fall schedule for the 302 member PBS stations throughout America.

An outspoken man, Mr. Iselin manages to remain sensitive to those around him and reponsive to the varied ethnic makeup of his WNET audience. At lunch recently at Alfredo's on Central Park South near the West 57th Street hedquarters of WNET, Mr. Iselin reveals that tact by subtly joining the interviewer in a futile search through the menu for low-caloric items - although he is trim and seemingly in perfect fighting condition.

Although acclaimed by many within PBS for his aggressive, literate programming stance, there are those who believe he is too competitive, ''a man with a Napoleon complex.'' Chats with top PBS executives have disclosed that some colleagues believe his ego sometimes takes him along routes that may benefit WNET to the detriment of the PBS system.

All seem to agree, however, that he is a knowledgeable risk-taker, willing to experiment with new programming ideas - and even new listing ideas such as the PBS magazine Dial, which currently seems to be a borderline financial venture. Sometimes this kind of adventurism leads to confused finances for his station, but he always seems to be able to balance the ledger with last-minute appeals for funding.

PBS president Bruce Christiensen told me about Mr. Iselin: ''We don't have a better judge of programming or a more creative person in the programming area.... He is straightforward, and you always know where his agenda is coming from. If you look at what WNET has produced over the years it is remarkable ... and it is largely due to Jay's creativity.''

Mr. Iselin's education - a BA in history and literature from Harvard University, a master's degree in law from Cambridge and a PhD in government from Harvard - stand him in good stead in choosing cultural programming on his station. However, he attributes much of the excellence of selection to his skill as ''a recruiter of talented people'' on the programming staff. He outlines the highlights of the new WNET season:

''This will mark the first anniversary of the single most pioneering undertaking that public broadcasting, led by Channel 13, has ever taken. That's the belief that each broadcasting day deserves enough full attention to the events of the day to merit at least one hour of prime-time programming in the field of public affairs: 'The MacNeil/Lehrer News Hour' will begin its second year.

''Then, we're doing 'The Brain,' ... to be accompanied by our series 'Nature, ' which represent part of a galaxy of programs which try to provide a sense of discovery.

''And, (there is) perhaps, the most outstdanding cultural education series ever assembled - the history of our civilization as told through the story of the Jewish people - ''Heritage: Civilization and the Jews,'' narrated by former Israeli Ambassador Abba Eban.''

Mr. Iselin points out other WNET-originated programs include ''Adam Smith's Money World,'' a new weekly live show on the global economy; ''Constitution: That Delicate Balance,'' a 13-part series probing constitutional rights, which will also be used as a college-credit course (as will ''The Brain''), and the return of three acclaimed classic series, ''Great Performances,'' ''Live From Lincoln Center,'' and ''American Playhouse.''

All of these programs will be available on most PBS stations, but WNET also presents a great deal of local programming.

Mr. Iselin believes that that the recent increase in the level of funds available to PBS, ''in open contradiction to the recommendations of the Reagan administration, probably more reflects (awareness) ... on the part of political representatives of the (high) degree of interest and support for public broadcasting across the country. They have the sense that PBS is a widely watched, dependable, and accessable service, a real national asset. ''

According to Mr. Iselin, the major change in PBS during the past decade has been ''the reconfiguration of the funding base of the system.... The great story is now the direct contact between the product and the consumer - our viewers.'' Listeners contribute a major part of the station's support (WNET has around 350, 000 subscribers) and ''out of that has come sensational programming. It has meant that the new generation of public broadcasters has developed self-reliance about the tastes and interests of a large part of the public and an ability to think in terms of a subscription-based service. That has been the really profound change.''

In addition, however, the station depends upon corporate underwriters to some extent as well as foundation support.''The Brain'' and ''The Constitution'' are both funded partially by the Annenberg/CPB Project.

While Mr. Iselin is against commercial interruptions on PBS, he is not averse to expanded underwriter credits. ''That represents an opportunity for a corporation to be credibly and tastefully identified before and after the program. In our tests, we found a lot of responsiveness, and we hope the FCC will allow further experimentation with the idea.''

In talking about other fund-raising methods for PBS, Mr. Iselin tends to discourage the idea of an income-tax check-off system whereby taxpayers could contribute to PBS on their income-tax forms. ''If one begins to use the check-off system for this, won't everyone begin to want to use it for other causes, too?''

Mr. Iselin believes that the 1984-85 season is climactic for WNET. ''A decade of experimentation, innovation, exploration has been happily culminated after an extraordinary period of financial testing. We have had the resiliency to take remedial steps to reduce costs, reconfigure production, and rethink approaches. And we've come up with a schedule which is not so much a climax as a precursor of what's in store down the road.

'' It's only a beginning.''

Comedy Zone'

From the very start, it appeared that ''Comedy Zone'' was turning into ''Combat Zone.''

Rumors leaking out of the New York studio where Comedy Zone (CBS, Fridays, starting Aug. 17, 8-9 p.m.) was being taped indicated that there were several internecine battles going on between producer and stars, that the starting date for the five-part series might have to be postponed (it was), that the show was turning out to be a disaster and might never see the light of prime time.

But now,''Comedy Zone'' is here, intact more or less. And it is worth all the Sturm und Drang.

''Comedy Zone'' is truly the ''innovative new series involving Broadway, Off Broadway, and television playwrights, performers, and directors'' claimed in the advance press releases. But it is not an overwhelmingly funny, thigh-slapping hour of hilarity. Rather it is filled with sly, witty, intellectualized humor, only occasionally slipping into slapstick. Perhaps too often, the concept of the sketch is more comic than the execution. But then, the show deals with material written by skilled craftsmen - writers such as Christopher Durang, John Bishop, Ted Tally, Jules Feiffer, and Wendy Wasserstein.

Comic stars of the show are Steve Allen, Bob Dishy, Steve Landesberg, and Penny Marshall. They are all adequately amusing. Joe Cates is the producer and co-director. His skill lies mostly in keeping the stars in line.

When Steve Allen announces at the top of the show: ''Stay tuned for serious comedy,'' he's not kidding. ''Comedy Zone'' ricochets from a Tally skit about the humorlessness of Russian topical humor to a Feiffer sketch about reverse paranoia.

''Comedy Zone'' is an hour of mirthful mental maneuvers, neither ha-ha nor ho-hum. Just good old-fashioned tee-hee humor.