It's hardly news that they're after Ernie Fitzgerald, the doughty Air Force financial analyst who persists in the notion that the public has the right to know how its money is spent. When have they not been?

This time, however, the administration thought-police are not just taking aim at him, but at all his kind in government service. If present plans succeed, the small band of whistle blowers, who are presently protected by law, will become an extinct species.

The new weapon against those the Pentagon regards as the enemy within is a government directive known as SF (Standard Form) 189, which makes employes pledge to keep secret not only classified but also "classifiable" material. What is "classifiable" material? Apparently anything that some skewered official decides -- after it has been made public -- was classified all along.

The official in charge of this new effort to choke off information and bully civil servants is Steven Garfinkel, director of something called Information Security Oversight Office (ISOO). He told a trio of aroused House committee chairmen that " 'classifiable' could mean anything."

Those refusing to sign will have their security clearances lifted. Since they need the clearances to do their jobs, they will likely become unemployed. Inevitably, Fitzgerald, who was fired in 1970 for telling Congress about the $2 billion cost overrun on the C5A transport plane and spent 12 years in court winning reinstatement, dug in his heels and refused to sign.

"I don't mind committing to protect legally classified material," said Fitzgerald, 61, "but I won't willingly sign away my liberties."

Fitzgerald went to court last week and won the right to wait until Aug. 21 before making his final decision. ISOO has been conferring with House Energy and Commerce Chairman John D. Dingell (D-Mich.), the scourge of defense contractors, and is promising revisions. No new version so far deletes the vague and chilling "classifiable."

Dingell, House Armed Services Chairman Les Aspin (D-Wis.) and Government Operations Chairman Jack Brooks (D-Tex.), a tiger on free speech, lead the opposition. Rep. Gerry E. Sikorski (D-Minn.) of the Post Office and Civil Service Committee will conduct hearings.

Sen. Charles E. Grassley (R-Iowa), a hero at home for his stand against Pentagon excesses, is on the case. The day after he read about Fitzgerald's latest jeopardy, he marched down to the White House to register his rage with chief of staff Howard H. Baker Jr.

SF 189 is a product of National Security Decision Directive 84, which caused a storm on Capitol Hill when it was unveiled in 1983. Its bold call for universal polygraph tests and pre-publication clearance for writers with security clearances occasioned passionately negative responses from Secretary of State George P. Shultz and former U.N. ambassador Jeane J. Kirkpatrick. Some backing off ensued.

But as the Iran-contra hearings, which suffered sadly from the want of a whistle blower, proved: People who want to keep secrets, even from each other, never quit.

SF 189 was issued last August and circulated in earnest in April. Only 24 people in government -- some in uniform, some not -- protested this assault on their liberties.

The administration test-marketed its monstrosity on Capitol Hill appropriately enough on the eve of the Iran-contra hearings, which were to reveal the lower depths of secret government. Brian T. Merchant, deputy director of security at the National Security Council, briefed Senate staffers on the need for secrecy and the urgency of signing SF 189. Those present, none of whom knew about lax security in the White House -- classified documents were altered during Merchant's watch -- signed the paper.

On the House side, however, they ran into Brooks, who was to become the most outspoken and uninhibited critic on the Iran-contra panels. He growled that "no member of my staff is going to sign this foolishness."

"This means you could get someone for telling his middle name or giving out 6-year-old weather reports," Brooks said.

House Iran-contra committee Chairman Lee H. Hamilton (D-Ind.), mindful of congressional prerogatives, agreed. House General Counsel Steven R. Ross was called in. After face-to-face negotiations with Attorney General Edwin Meese III, the House drew up its own pledge. It was a statement that staff members would obey the law against revealing classified information and had no mention of pre-publication clearance. Those House staff members who had signed SF 189s were allowed to substitute the congressional version.

"I would sign the congressional pledge in a minute," Fitzgerald said. "I wish I could. What's good enough for Jack Brooks is good enough for me."