Senate Majority Leader Robert C. Byrd (D-W.Va.) said yesterday he isn't certain the Senate will debate this year a proposed 39-month extension of the deadline for passage of the Equal Rights Amendment.

The House voted 233 to 189 Tuesday to extend the ERA ratification time limit to June 30, 1982, from its current deadline of next March 22. However, the measure is threatened with a filibuster in the Senate.

Senate backers of an extended ratification period said yesterday they are confident of breaking a filibuster. Supporters led by Sen. Birch Bayh (D-Ind.), say they won't push for consideration if an extension until they have the 60 votes needed to invoke cloture, and that they are about 10 votes shy.

"The game plan is to secure enough votes on a petition for cloture to ward off the filibuster threat," said one ERA strategist.

Asked about Senate prospects for action on the extension, Byrd said, "I don't know. As of now I just can't say." He said he hoped the Senate would have time to debate the measure , but noted, we have so many things to get done in so short a time" as Congress tries to adjourn in October.

In the Senate, a version of the extension measure that would push back the ratification deadline by seven years has become stuck in a subcommittee. That means the Senate likely will ignore its measure and deal directly with the House-approved 39 month extension when it returns from the Labor day recess.