A Senate committee yesterday tentatively approved amendments to President Carter's civil service revision bill that would give a bit more bite to the watchdogs it sets up to protect federal employe's rights.

The amendments would expand the powers of the proposed special counsel and provide for an annual report to Congress by the new Merit System Protection Board.

The committee turned thumbs down, however, on a measure that would have reduced the flexibility the bill gives top officials in the deployment of the proposed elite corps of managers, the Senior Executive Service.

In a mark-up session that was livelier and better attended than others held thus far, the committee also set the stage for a showdown at its Wednesday session. It deferred until then action on a number of disputed amendments that its members, particularly Sen. Charles McC. Mathias (R-Md.) brought up.

On the key issue of procedures for firing federal employes, Sen. Charles Percy (R-Ill.) introduced what one committee sources called "an important compromise" that would change the standards of evidence required. The compromise would make it easier for managers to fire employes for incompetence than it is now, but not as easy as it would be under the administration-backed bill.

The Percy amendment separates into two categories dismissal actions taken against allegedly incompetent employes and dismissal actions taken "for cause" (misconduct, such as drunkenness on the job).

The amendment calls for a tougher standard in cases of misconduct (the employer must show "substantial" evidence) than in cases of incompetence (the employer must show only "reasonable" cause).

Administration spokesmen called the Percy amendment "reasonable", but Sen. Mathias, for one, indicated he will try to win additional employe protections.

As expected, Mathias introduced a number of amendments designed to do that yesterday, with more expected Wednesday. Mathias, whose constitutency includes Montgomery County where many high-ranking government workers live, has called the president's bill to "management-oriented."

Though both Mathias and committee chairman Abraham Ribicoff (D-Conn.) indicated Percy's compromise had the votes needed for approval, Ribicoff postponed action on that and similar issues until Wednesday to give members more time to reconcile their differences.