What began last month as a campaign by Sen. Jesse Helms (R-N.C.) and other conservatives to eliminate a "liberal bias" in CBS Inc. news coverage is making the $4.9 billion communications company more vulnerable to a takeover, Wall Street experts say.

The biggest risk to CBS is not that Fairness in Media -- the North Carolina-based group backed by Helms -- will be able to buy enough stock to control CBS, according to Wall Street analysts and investment bankers. Instead, the greater risk is that some Wall Street takeover specialist will make a bid for the company amidst the turmoil, these sources said.

On the other hand, CBS would have some powerful defensive weapons at its disposal in such a fight, the analysts said.

"Most people on the street [Wall Street] do not put much credibility on Fairness in Media's proxy fight. On the other hand, it raises the profile of the company [CBS]. To the extent it makes CBS appear more vulnerable, it may create interest among other sharks," said Mark Riely, an analyst with F. Eberstadt & Co. Inc.

Analysts and corporate takeover specialists said they believe that CBS is at risk because the sum of its parts is considered to be worth more than the stock market's valuation of the whole.

One of the reasons for this is the price that television stations are selling for in the current market. CBS owns highly valuable television stations in New York, Los Angeles, Chicago, Philadelphia and St. Louis.

CBS stock has been selling for about $80 a share. Estimates suggest that the company's principal assets, if they were sold one-by-one, could be worth as much as $110-a-share to $170-a-share, according to interviews with investment bankers and Wall Street analysts. "In the real world, everything has a price. On a liquidation basis, CBS is worth considerably more that it is selling for [on the stock market]," said R. Joseph Fuchs, a Kidder, Peabody & Co. Inc. analyst, echoing the views of other experts.

Therefore, a corporate raider could pocket a sizable profit by purchasing more than half of CBS stock and then voting to bust up the company and sell the assets. The raider could offer stockholders a premium of about 35 percent over the market price and still have the potential to profit on the transaction, experts said.

While no such raiders have stepped forward, experts believe they are sharpening their pencils and trying to decide whether to make their move.

CBS is, of course, not the only industry attraction for the takeover specialists. For about two years now, American Broadcasting Cos., parent company of the ABC television network, has been mentioned as a takeover target, most recently about three weeks ago.

Savvy Wall Street financiers like Saul Steinberg could view CBS as an attractive takeover target, and Cable News Network founder Ted Turner has stated in the past that he would like to control one of the networks, although Turner hasn't publicly expressed an interest in CBS since its battle with FIM began.

An investor group that included both financial and broadcasting experts could pose a threat to CBS, experts said, especially since such a group could retain the services of an investment banking firm such as Drexel Burnham Lambert Inc., which has the power to raise tremendous sums quickly to finance hostile takeover bids.

CBS reported record revenue and profits in 1984 of $4.92 billion and $212.4 million respectively, an increase in profits of 13.5 percent over 1983.

Analysts credit CBS Chairman Thomas H. Wyman with doing an excellent job identifying what businesses the company should be in and what businesses it should abandon.

Last year, CBS made a major acquisition by purchasing a group of magazines from Ziff-Davis Publishing Co. and took a large loss when it decided, to the applause of analysts, to get out of the musical instruments business.

CBS continues to be the leading network in primetime, daytime and evening news, and Dan Rather, one of the targets of FIM's campaign, continues to be the most popular network anchorperson. The phenomenal success of CBS Records in the last few years, including Michael Jackson's "Thriller" album, the largest-selling record by a single artist in recorded music history, will be difficult to maintain, analysts said.

Experts said arbitrageurs, institutional investors and takeover specialists have been reviewing broadcast stocks to determine which of them are potential takeover targets. The publicity surrounding FIM's campaign could prompt bids from raiders interested in profits, not politics.

CBS has about 29.7 million shares outstanding, two thirds of which are owned by institutions, rather than individual shareholders. FIM's campaign, including the mailing of one million letters to individuals and asking them to buy at least 20 shares of CBS each, is an attempt to organize individual shareholders to gain influence over corporate and network affairs. But strong institutional ownership of CBS and other factors make it difficult for the FIM strategy to succeed, according to Wall Street analysts.

For example, CBS's rules for electing directors make it difficult for a minority of shareholders to gain seats on the company's board.

But it is clear from discussions with sources close to the situation that FIM is considering other ways of putting pressure on CBS. Last week, FIM said in a Securities and Exchange Commission filing that it is holding discussions with third parties about transactions to seek control of CBS. The documents did not identify the third parties.

The current total stock market capitalization or value of CBS is approximately $2.4 billion, while the estimated break-up value of the company could approximate $4 billion, depending on market conditions when the assets are sold, according to analysts and investment bankers.

Institutional money managers, who would sell their shares if a raider offered a significant enough premium to the CBS stock price, clearly control the future ownership of the company. The company's biggest single stockholder is William S. Paley, who controls about 1.9 million shares or 6.4 percent of the company.

In addition to the standard takeover defenses against hostile bidders, CBS could try to bleed a bidder by making the takeover process lengthy and costly. This strategy might discourage a raider from hanging on in a lengthy battle because the annual interest cost to the raider who borrows money to finance a CBS takeover bid could exceed $250 million.

The Federal Communications Commission would have to approve a transfer of broadcast licenses, CBS lawyers noted in a recent court filing. Presumably, CBS lawyers could take advantage of this requirement to make a takeover attempt both lengthy and costly, sources said.

Some experts believe that any realistic analysis of the break-up value of CBS must recognize that some of the value would be diminished unless the network and the five owned and operated stations in New York, Los Angeles, Chicago, Philadelphia and St. Louis were controlled by the same party. Selling them separately might not reap the full benefit, while finding a buyer able to afford the entire package at a premium price could be difficult, analysts said.

The reason to keep them together, experts said, is that the television stations in the major markets serve as important outlets for network programming, and also encourage affiliated staions around the country to be loyal to the network.

Another possible outcome of the battle for control is that CBS could end up in the hands of a white knight, or friendly acquirer. Another possibility is that the FIM campaign will generate more publicity than action, leaving CBS as a broadly held public company.

Another possibility is that FIM will team up with a group of wealthy conservative investors and launch a hostile bid for CBS.

Whatever the outcome, the FIM/Helms campaign to eliminate what they believe is a liberal bias in news coverage at CBS is a difficult event for many Wall Street analysts to interpret. Typically, takeover bids and proxy fights are launched for economic reasons. In this case, political and philosophical beliefs are the driving forces.

CBS issued the following statement in response to the initial FIM, SEC filing:

"CBS News reports the news as accurately and fairly as it can independent of any political point of view. Its sole purpose is journalism. Its goal is total objectivity. To seek control of a corporation for the sole purpose of subjecting its news to political influence contradicts the traditions of a free and independent press. CBS intends to take all appropriate steps to maintain the independence and integrity of its news organization."

In his letter to one million Americans, asking for support of the bid to influence CBS, Sen. Jesse Helms wrote the following:

"For years good Americans like you have asked President Reagan and me what can be done to combat the flagrant bias in the liberal news media. . . . At last there's an answer to that question.

"The answer is for you and other Americans like you to switch a portion of your Analysts credit CBS Chairman Thomas H. Wyman with doing an excellent job identifying what businesses the company should be in and what businesses it should abandon. savings and investments into stock . . . in one of America's largest TV networks.

". . . FIM is launching a nationwide campaign, very much like a presidential campaign, to end the liberal bias at CBS by urging conservatives to purchase enough CBS stock . . . if necessary to control the network.

". . . So please, even if you can't shift some of your investments to CBS stock, please send FIM a contribution today of $15 or $25. If you can send more than $25, bless you!

". . . FIM is counting on you to become Dan Rather's boss -- by switching a portion of your investments to CBS stock."