With barely a ripple of notice, Richmond's nighttime television viewers and radio listeners have been tuning in this season to a revolution.

The delivery is soft: On screen, a montage of black and white snapshots evokes images of Woodstock, Haight-Ashbury and Beatlemania -- reminders of how times have changed. But the pitch is for a new over-the-counter contraceptive -- one of a category of products long banned from advertising by the three major networks.

"When the spot for the Today contraceptive sponge came in," recalls Wanda Lewis, general sales manager of WTVR, the CBS affiliate in Richmond, "I said, 'Look, we are such a conservative station. We'll never run anything like that.'

"Then we saw it. If you'd seen the spot, you'd be very surprised. I was. It doesn't talk about contraception at all until the end of the spot. It just says you have a choice."

Like other Richmond TV and radio stations that took the ad -- several refused -- WTVR has been buoyed by the virtual absence of viewer complaints, even after the spot was moved up first to the early evening and then to afternoon time slots. Says Ellen Shuler, Lewis' counterpart at WWBT, the NBC affiliate, "We received zero letters and only one phone call, from a priest."

It's a reaction the manufacturers are banking on.

In recent months, VLI Corp. of Irvine, Calif., and the Thompson Medical Company Inc. of New York -- the makers, respectively, of the Today sponge and Encare vaginal suppository -- have led an assault on the network ban by test-marketing their products on independent and network-affiliated TV, cable and radio stations across the country.

Strongly backing their efforts is a task force of at least 10 health and public interest groups, including the American Public Health Association, the Children's Defense Fund and the National Urban League.

"Some of us feel we're on a mission," says Marty Johnson, vice president management supervisor of the Keye/Donna/Pearlstein ad agency in Los Angeles, which handles the VLI account, citing a more than 50 percent rate of unwanted pregnancies, including 1 million a year to teens.

"People out there need help. Yes, we're trying to make sales for this company," she concedes. "But more than that, we're trying to get the word out and break the taboos against advertising."

Argues Donald Lepone, vice president of marketing for Thompson Medical, the maker of Encare: "We believe consumers are entitled to learn about birth control from what's been called the greatest sex educator of all time -- the television. It's time we face the problems of unwanted pregnancy maturely and understand if we're going to show our children 'love in the afternoon' is okay -- that's what they refer to 'soaps' today -- we sure better show them how to prevent pregnancy in a responsible, tasteful format."

Richmond's example notwithstanding, public opinion on the issue is divided.

Callers asked to comment on an Encare spot aired nationally on the New York-based Owen Spann talk show (WABC radio) described it variously as "one of the best, most intelligent commercials I've ever heard in my entire life" and "immoral, depraved and properly banned."

Meanwhile, the anti-abortion American Life Lobby is leading a petition drive against the ads. Lobby legislative director Stephanie Johnson says children should not be exposed to the ads via TV: "We believe parents should determine what information they want to give their children about birth control."

In a 1981 survey by the National Association of Broadcasters (NAB), slightly more than half of 2,000 adults polled objected to contraceptive advertising on radio or TV. In Washington, the Center for Population Options calls the survey "flawed" because it predated existing product ads.

"None of these people had ever seen any contraceptive ads," says Anne Kastor, CPO program associate. "When you talk to them about it, what they think is we're going to have sex orgies on TV." The latest airwave war was fueled by the 1982 suspension of the NAB code on programming and advertising. The code, containing language against contraceptive ads, was dropped as a result of an unrelated Justice Department antitrust suit. In 1983, CPO formed its task force to deal with the issue. The networks have meanwhile adopted individual policies against advertising for contraceptives and such other categories as astrology, firearms and massage parlors.

CBS policy, for example, was described in a recent letter to CPO from Donald Wear Jr., vice president of policy: " . . . On the CBS Television Network we strive to entertain and inform, but not to offend. While some believe that . . . contraceptive advertising on a national level is needed, a great many others would find this kind of advertising an intrusion on their moral and religious beliefs and take offense."

CBS officials say the network policy is unrelated to questions about individual products' safety or efficacy. "We haven't gotten that far," said George Schweitzer, vice president of CBS communications. The sponge, with an effectiveness rate near 85 percent, has been the subject of scrutiny with regard to safety. (The FDA said in November, however, that only 12 documented cases of toxic shock syndrome among the product's 600,000 regular users made it "relatively safe.")

Opponents of birth control advertising still cite safety as an argument. Says Stephanie Johnson of the American Life Lobby: "If this TV advertising came out 10 years ago when the Dalkon Shields came out, imagine all the kids who might have been running around with Dalkon Shields." The Dalkon Shield, an intrauterine contraceptive device, has been blamed in some 3,600 lawsuits for allegedly causing pelvic infections, spontaneous abortions and sometimes death.

The strongest push to change network policy on contraceptive advertising has come from the manufacturers of the new, so-called "female" nonprescription products, comparatively little known in the U.S. marketplace. These include Today, Encare and Semicid, a vaginal suppository whose manufacturer, Whitehall Labs, has advertised some on cable TV.

Today, introduced by VLI in June 1983, is a small, disposable polyurethane sponge, treated with spermicide and effective for 24 hours. It sells for a little over a dollar. Today ads first went on TV this fall.

Encare led the TV market drive with its appearance last January on Cable Health Network (now Lifetime) and USA Cable, and then hit the big time in April with its appearance on WTBS, Atlanta, received by 40 million households.

Encare, a foaming suppository effective up to an hour, was purchased by Thompson Medical in 1982, five years after it was introduced. A package of 12 generally costs between $3.60 and $4.30. Like Today, Encare has a recognition problem. A company survey of 1,000 women showed only 3 percent were aware the birth control method existed.

Manufacturers of other kinds of contraceptives are, meanwhile, watching with interest. As prescription drug manufacturers, makers of the Pill are under an FDA moratorium from advertising on TV. Condom manufacturers, whose products account for more than 60 percent of the over-the-counter birth-control market, have little incentive at present to join the TV fray. But that may change.

Ansell Inc. has experimented with radio ads for its relatively new Lifestyle line. And Trojans, the leading brand sold, had a fling with TV in 1975, only five years after condoms came out from behind the drugstore counter. The experiment was on ABC's San Jose affiliate, KNTV.

"When the ad was first run," recalls Lewis Brenner, advertising director and sales manager at Youngs Drug Products Corp., the maker of Trojans, "the station was flooded with complaints: 'How can you do this awful, terrible thing?' So they yanked the commercial."

The story, he says, was leaked by a wire service, and the next day a San Francisco newspaper ran it, with either a headline or first line that read: "First rubber commercial snaps."

"There was a backlash," says Brenner. "People said, 'My God, you have hemorrhoid preparations, jock itch products, rape and incest on your programs. Why can't you have a commercial for a contraceptive?' So, the station ran the commercial free on the 6 p.m. news and set up a hotline and box number for viewer comments. They got a 17-to-1 response from people that the ad should go back on the air, and back on the air it went, without the world coming to an end."

But the experiment was not repeated. Condom manufacturers have since concentrated on improving their image in print, where, says Brenner, giants like Time, Newsweek, Life and Cosmopolitan still won't take their ads.

"Very frankly," he says, "we're not going to beg anybody to take our money.

"Plus, I don't know how cost-efficient it would be. TV's very expensive. We're not Johnson & Johnson or General Motors. They networks seem to have this idea that our product is dirty and offensive, that if they carry our ad, there will be orgies in the street. You can use the same reasoning to argue that carrying seat belts causes reckless driving."

So far as the female contraceptive ads, tastefulness has not been an issue.

Viewers of Today and Encare ads often say the ads are more innocuous than they imagined. Encare's spot, for example, features four women, seated and discussing the product, which is shown in its drugstore package only. So innocuous is the Today spot, says Jim DeSchepper, program manager for Richmond's WTVR, "I seriously doubt many viewers will even know what they're watching unless they're seriously interested in the product."

In contrast, a government-sponsored TV spot for the use of contraceptives in Sweden is not nearly so subtle. A young woman tells her partner she's gone off the Pill. What's she going to use instead? he asks. "Guess," she answers, snapping a condom against his bare bottom.

Is this what U.S. audiences are in for if contraceptive manufacturers carry the day? No, CPO argues. Should the networks allow contraceptive advertising, they would still retain full control over ad content. Ads viewed as tasteless could be rejected or sent back for revision.

On a broader social level, the power of such advertising to do more than advance sales is largely untested. Advocates point, however, to Sweden's teen pregnancy rate of 31.6 per 1,000 women in 1981, the most recent year tabulated. The comparable rate in the U.S. was 110.8.

How likely is a network conversion?

Offers Marty Johnson of Keye/Donna/Pearlstein: "It's really just a matter of enough experience on other stations to show them there will not be a backlash from their viewers. The networks are going to be the last to accept us. They readily admit they lag behind social opinion . . . I hope they'll come around sometime next year. But I'm optimistic, very optimistic."

Says Lepone of Thompson Medical: "We have to remain committed. We look for small victories to keep us encouraged . . . I don't know when it will happen. I just have confidence that the bright people over there will realize how important it is and take courage and put birth-control advertising on the air where it belongs."