PUBLIC TELEVISION and radio have come a long way since the first Carnegie Commission report a dozen years ago. That commission's recommendations, with one key exception, became the base of the legislation that changed public broadcasting from a local affair into a national institution. Congress adopted its proposals to create a Corporation for Public Broadcasting, insulate it somewhat from political pressures and provide it with federal funds. But Congress rejected the idea that it place a tax on the sale of television sets and dedicate the revenue from it exclusively to public broadcasting.

The second Carnegie Commission, which released its recommendations last week, is still trying to fill that gap.While it wants to reorganize the existing public-broadcasting bureaucracies and to protect them better against political interference, its key recommendation is that Congress levy a fee on those who now use the public airways as a way to provide the additional funds it says public broadcasting should have. The biggest fees would be imposed on those who make a profit out of that use -- commercial television and radio stations, like those owned by this newspaper. Fees would also be imposed on other users of the radio spectrum, such as citizens' band and mobile radio operators.

The idea of these user fees is not new. Rep. Lionel Van Deerlin (D-Calif.), who heads a House subcommittee that is attempting to rewrite the communications act, has already drafted legislation to levy them on commercial broadcasters. Given the strong opposition of most broadcasters to such proposals, it is not clear whether they will fare better in Congress than did the original proposal for an earmarked tax on the sale of television sets. Congress refused then and chose to provide federal funds through direct appropriations.

It is clear that the new commission would prefer for Congress to dedicate a tax, any tax, to public broadcasting. That's because a guaranteed source of income would permit better long-range planning and help free public broadcasters from political pressure. But the commission shied away from making such a recommendation to avoid the old argument about whether any public institution, particularly one involved in forming public opinions and attitudes, should have so large a measure of financial independence.

If the commission can persuade Congress to appropriate more money for public broadcasting and impose the spectrum fees to raise at least part of the additional funds, it may succeed in doing indirectly what Congress refused to do directly a decade ago. An appropriation with such an offset might soon come to be regarded as a fixture rather than a continuing item in each year's budget.

We would prefer not to see these matters so closely linked. If public television needs more money from the federal government -- and there is a substantial argument that it does -- the case for that should be made without regard to where the money will come from. If it is in the public interest to impose license fees on users of the airways, they should be imposed without regard to where the money will go. By tying the two together, the commission has deflected attention somewhat from the key questions in public broadcasting's future: What changes are needed in its bureaucracies and what, besides just more money, does it need to improve its programming as much in the next dozen years as it has in the last dozen?