Operating out of a mail drop on K Street, an independent campaign fund-raising committee run by a Tampa, Fla., lawyer raised nearly $300,000 from supporters of Ronald Reagan, according to reports filed with the Federal Election Commission.

Yesterday, six days after Reagan was overwhelmingly elected, the lawyer, Sheldon L. Wind, refused to identify the principals of his 1980 Republican Presidential Campaign Committee or those behind two companies to which the committee sent $270,000, $90,000 of it in the closing days of the campaign.

Wind, maintaining he did "nothing wrong," said yesterday that the people involved simply "don't want to be known."

Also not fully known is how more than $100,000 of the $270,000 was spent.

The committee's operations show how easy it is to keep some key information secret, even from the FEC.

When the committee's organization was filed with the FEC on July 11, Wind listed its address as Suite 520, 1629 K St. NW, the address of Courtesy Associates, a firm that provides mail-fowarding services to clients wanting a Washington address.

Wind, as treasurer of the committee, gave the same K Street address and listed himself as S. Louis Wind.He dropped Tampa from the listing of his telephone bills: as reported to the FEC in October, the expenditures went to General Telephone Co., P.O. Box 350, with no city listed.

The major recipient of committee funds was listed as American Campaign Consultants Inc., at 1377 K St. NW, Suite 124. Between Sept. 2 and Oct. 24, the committee reported to the FEC it had sent American Consultants $228,000.

The K Street address is home for The Mail Box, a firm that rents mail boxes, including Box 124.

American Consultants is a Tampa corporation formed in May. The lawyer who set up the company, G. Russell Stahl, said yesterday that Wind "asked if I would turn the company." Stahl added that he was paid by another individual, whom he refused to identify, citing the lawyer-client relationship. i

Stahl recalled that the man said they were "going to do fund-raising for Reagan," and said he charged them only $200 "since I was for Reagan."

In the closing days of the campaign, Wind's committee reported spending a total of $165,000 on media. The first expenditure was $75,000 to American Campaign Consultants on Oct. 15. It is not known how that money was spent.

In a telegram to the FEC on Oct. 23, the committee reported spending $40,000 for pro-Reagan advertising two days earlier, through Advertising America Inc. in the Americana Building in Houston, another address that turned out to be a mail drop.

Robert L. Rolnick, a Houston lawyer who incorporated Advertising America in early October, said last week that his clients would not permit him "to disclose any information about the corporation."

In an interview with CBS last week, Wind said in answer to a question as to whether he was involved as an officer of Advertising America: "I don't know, maybe."

On Oct. 25, Wind sent the FEC a telegram reporting a $50,000 expenditure by the committee the previous day to American Campaign Consultants.

On Oct. 21, Wind presented a cashier's check for $15,000 to Rsa Agency, an advertising firm in St. Petersburg, Fla., according to Peggy Pendergrass, owner of the company. Wind wanted some work done on a one-minute Reagan radio commercial and asked Pendergrass to place the spot on stations in several states.

Two days later, according to Pendergrass, Wind returned with a $20,000 cashier's check and asked that a 30-second television commercial be made and placed in several Florida markets and in Chicago. The commercial was completed and sent out the next day.

Pendergrass said yesterday that she believed he was paying her as treasurer of the campaign committee and that she would be sending her invoices to him in Tampa.

Wind said Pendergrass "had misunderstood" and that the cashier's checks "were from the vendors, not the committee," but refused to say which one. If the checks were direct payments from the committee, they should have been reported to the FEC, which they were not. If they were part of the $90,000 in expenditures reported by the committee, the disposition of the other $55,000 is still not known.