If the super-secret National Security Agency transmits a detectable public image from its digs at Ft. Meade, Md., it surely is a blurry one: a large, shadowy establishment with arcane devices that enable it to monitor almost anyone's communications, anywhere, anytime.

Now an unusual new blip is showing up on the screen. The 25-year-old agency, created by President Truman with a secret executive order, has fired an official named Richard P. Floyd, who lives in Silver Spring. He is fighting back, and has told his story to the press.

To be sure, the story in some ways is the kind one can pick up nearly anywhere in the federal bureaucracy - the evocations of soured relationships, the confusing charges and counter-charges, the dreary minutiae of a grievance.

In summary, a nasty dispute developed between Floyd and certain associates, particularly his boss, Elizabeth R. Haig. She filed charges that he denounced as libelous. He asked for a grievance hearing. The NSA official who conducted it agreed with Floyd that the root of the problem was "the monstrous workload" in their unit. He recommended that the agency find another outlet for Floyd's "exceptional talents and potential."

Instead, NSA's new director, Vice Adm. Bobby R. Inman, after giving "full consideration" to the file, decided that Floyd's grievance "is not sustained." Floyd was fired from his $38,293 post as chief of the Procurement Support Division, but he said he intends to appeal to the Federal Employee Appeals Authority.

The unusual aspects of the story relate to what Floyd portrays as the use of "national security" as a shield for abuse of employees unprotected by civil service.

In a thick stack of unclassified papers that Floyd gave to The Washington Post is an angry letter he gave to Inman July 20.

Floyd, a 47-year-old lawyer and linguist who has been with the agency since its inception, wrote that if his firing stands, "no one in NSA is safe from unqualified supervisory reprisal."

He made the charge after NSA information officer Norman Boardman granted Floyd's request for a copy of the unclassified transcript of the grievance hearing.

But Boardman, terming the transcript an "official" NSA document, told Floyd not to circulate it. He invoked regulations implementing a 1959 law relating to the NSA.

The law says merely that it does not "require" the NSA to disclose, among other things, the names, titles or salaries of agency employees. But as interpreted by Boardman, the law "protects" information such as that in the transcript.

Floyd, in the letter to Inman, characterized Boardman's directive as "intimidation, to preclude any dissemination of a perfectly unclassified document . . ."

He went on to tell the NSA director, "I suggest that you cannot demand anonymity in the name of national security, and suppress your subordinate's gross administrative abuses under the protective legislative immunity" of the 1959 legislation, Public Law 86-36.

Inman declined to comment. The Defense Department, of which the NSA is a part, said that pending the outcome of Floyd's expected appeal, "we have no further comment to make."

Floyd and Haig, chief of a unit called L4, had, the papers indicated, gotten along well until late last year. Then, Haig said in a request for a medical and psychological evaluation of Floyd, there occurred "a number of explosive and argumentative incidents" that were adverse to his productivity and relationships with co-workers and superiors.

Replying in letters to Joseph P. Burke, NSA's director of civilian personnel, Floyd cited statements by Haig that he called "untrue or defamatory."

Floyd asked for a grievance hearing by "an external examiner."

His complaint also named Burke, who incorporated Haig's allegations in what Floyd referred to as "an irresponsible synthesis."

Meanwhile, in a report on the medical psychological examination, Dr. Robert L. James wrote that it "did not show sufficient evidence to make a diagnosis of psychiatric disorder."

Nonetheless, James asked an outside psychiatrist acceptable to Floyd, Dr. S. Eugene Long, to make a "fitness for duty evaluation," and in an action bitterly protested by Floyd, armed him with Burke's "irresponsible synthesis."

But in a report on May 14, Dr. Long, while saying that Floyd's exhaustion from over-work and, possibly, his high blood pressure could have exacerbated matters, concluded that he could "find no indication of psychiatric disorder, nor of significant anxiety felt as such by Mr. Floyd."

The grievance hearing was held in mid-June. Charles W. Matthews, an NSA employee who conducted it, concluded:

Floyd remained "highly productive" in the few months preceding Haig's request for a medical evaluation, even though his strong feelings of right and wrong, temperament and job pressures helped to set off "incidents that adversely affected his overall productivity."

The incidents did not impede Floyd's ability "to effectively provide supervision and direction to his subordinates."

Haig's allegations were not "libelous," and there is "no substantial evidence of malicious intent" on her part.

Matthews urged the agency to relieve "the blatant potentially explosive understaffing conditions" which, as noted, he perceived as a root cause of conflict.