The Federal Communications Commission is expected to slap Infinity Broadcasting Corp. with a record fine of up to $ 750,000 in connection with allegedly “indecent” broadcasts made by shock jock Howard Stern.FCC sources said the decision could be announced as early as today, and will contain a warning notifying Infinity management that station license-revocation proceedings will be initiated if the broadcaster further violates FCC indecency rules. Not all of the news out of the FCC will be bad for Infinity, however. Announcement of the fine is expected to be accompanied by the commission’s approval of Infinity’s $ 100 million purchase of three stations owned by Cook Inlet Radio Partners: WZLX-FM, Boston, WUSN-FM, Chicago, and WZGC-FM, Atlanta. There had been some speculation that the FCC also would attempt to block Infinity’s purchase of the Cook Inlet Properties, but commission attorneys apparently believe such action could not be legally justified. The indecency fine against Infinity would be the largest in FCC history, and may come in the form of a $ 250,000 fine each against Infinity stations WXRK-FM, New York; WYSP-FM, Philadelphia; and WJFK-FM, Washington, D.C. All three fines target allegedly indecent remarks made on “The Howard Stern Show” in October and November 1991. Six weeks ago, the FCC fined Greater Media’s KSLX-FM Los Angeles $ 105,000 in connection with its carriage of the same late 1991 Stern broadcasts. Among the targets of Stern’s barbs: blacks, actress Michelle Pfeiffer and his Los Angeles radio rivals Mark and Brian. Stern’s bad-boy campaign has divided broadcasters. Many believe he is an embarrassment to an industry that has long prided itself on service to the public. Others criticize the FCC for an alleged “witch hunt” by not stating specifically what Stern may or may not say. Stern did not endear himself to the commission when — with FCC chairman Al Sikes in the hospital with prostate cancer — he said over the air that he hoped Sikes would die of the disease. Infinity prez Mel Karmazin recently made a trip to Washington to meet with FCC members and their staffs, but sources said Karmazin’s trip did little to persuade the commission to lighten the penalty against Infinity. Stern received support this week from unlikely quarters: Sen. Alphonse D’Amato (R-N.Y.). In a letter to Sikes, D’Amato said he is “deeply concerned” by the FCC’s “contemplated actions” against Stern. D’Amato said there is a “strong impression” that the attack on Stern is being driven by “political pressure from narrow interest groups. … Government action to limit free speech, whether in response to the religiously motivated right or the politically correct left, is un-American,” D’Amato wrote. During D’Amato’s recent tough re-election campaign, he appeared on the air with Stern and won the shock jock’s endorsement.