The "who gave it - who got it" reforms in the Federal Election Campaign Act of 1971, which require federal political campaigns to disclose the identities of their major contributors, don't work.

The disclosure law is supposed to let the voters know who (tied to which economic interest groups) is financing their politicians' campaigns. But limitations of the law, persistent violation by campaign organizations, and lax enforement by the Federal Election Commission (FEC) defeat this purpose.

Consider the campaigns of the 21 senators who sought reelection last fall (excluding former senator Wendell Anderson, an incumbent who appointed himself and had never before run a federal campaign). All had previously run and won under the same disclosure provisions of the law, which became effective on April 7, 1972. As incumbents, they were in a better position than most candidates to know the requirements of the law. As senators they tended to run bigger, better-organized, better-funded campaigns than House members. If any campaigns should have complied with the law, these Senate reelection campaigns should have.

Yet more than half of the contributors to these campaigns were not fully identified to the voters last election day.

The law exempted more than a third of the funds from disclosure. Congress wrote a law that does not require campaigns to identify contributors who give $100 or less, conveniently excluding those who buy tickets to that time-hornored political institution, the $100-a-plate fund-raising dinner. Anaverage of 22 percent of the money these senators reported spending on their 1978 reelection campaigns came from undisclosed sources, because it came in amounts of $100 or less.

Another loophole is deficit campaign financing. If campaigns go into debt and don't raise their money until after the election, then they of course don't report it until after the election. Except for contributions of $1,000 or more, money raised in the final two weeks of campaigning before an election is also exempt from disclosure until after the election. An average of 12 percent of the money spend on 1978 Senate reelection campaigns came from contributors whose identities were not disclosed to the voters before election day because it was raised late in the campaign, was raised after the election, or has yet to be raised to retire outstanding debts.

(Fourteen of the senators elected in 1978 ended their campaigns with debts of more than $30,000, an increase compared with 1976, when only five senators had campaign debts that high.)

The rest of the money came from political parties, from political action committees formed by various interest groups, from the candidates themselves, and - two-thirds of it - from individuals who gave amounts of more than $100, prior to the election.

Under the law, these individuals should have been identified by full name, address, occupation and place of business, if they had an occupation and place of business.

But a sampling of the reports filed by Senate reelection campaigns for the period October 1-23 shows that more than 35 percent of these contributors were not properly identified. (Nearly a quarter of the listings did not include a place of business or the required notation that the contributor was self-employed or otherwise without a place of business.)

Ironically, the campaign that had the most effective fund-raising operation had one of the worst records of complying with the disclosure law. Sen. Jesse Helms (R-N.C.) raised more than $7 million a record amount for a Senate campaign. In his final pre-election campaign-finance report, Helms listed 677 contributors of more than$100. But 572, or 84 percent of them, were not properly identified as required by law.

The FEC doesn't have enough staff assigned to the task of enforcing the law, a situation that isn't likely to change in the foreseeable future. The agency's budget request for fiscal year 1980, which is expected to be cut before it gets through the congressional appropriation process, includes no money for additional staff to review and analyze campaign finance reports. If Congress wanted a strong FEC, it would legislate one. But for 1980, as for 1978, it's likely that "full disclosure" of campaign finances will be more of a goal than an accomplished fact.