After a week of essentially predictable votes on the probisions of SALT II, the Senate Foreign Relations Committee yesterday began discussion of proposed amendmentes that could significantly alter the treaty.

The new amendments, all of which relate to U.S. capability to monitor Soviet compliance with SALT II, probably will be voted on later this week.Committee sources speculated yesterday that pro-treaty forces will have problems blocking the amendments.

The amendment htat has the most apparent appeal will be proposed, perhaps in differing forms, by Sens. John Glenn (D-Ohio) and Richard G. Lugar (R-Ind.) Both Senators propose eliminating from the treaty, in effect, a provision that would allow the Soviet Union to conduct most ot its tests of land-based missiles without notifying the United States in advance that the tests were about take place.

The treaty provision that both senators want to amend is one of a handful that Carter administration officials acknowledge apply unequally to the Soviet Union and the United States. In effect, the provision requires the United States to give the Soviets advance notice of all its land-based missile tests, while allowing the Soviets not to give notice on most of their tests.

Before the loss of American listening stations in Iran -- which could pick up the radio transmissions from Soviet test flights moments after blastoff -- this distinction was not regarded as significant. But the various intelligence-gathering techniques now under consideration to make up for the loss of the Iranian posts could all be vastly more effective if the United States had prior notification of Soviet tests.

The provision in question requires prenotification of all single ICBM lauches by either country "except for single ICBM launches . . . which are not planned to extend beyond its national territory."

American test launches all leave U.S. national territory, landing at sea, but the Soviets' most-used test range goes from Tyuratam in southern Russian to the Kamchatka peninsula near Alaska, all within Soviet territory.

Glenn and Lugar yesterday announced their intentions to address this matter with proposed amendments later in the week. Carter administration officials met among themselves and with the committee in closed session yesterday to discuss these and related proposals.

Earlier yesterday the committee voted unanimously to adopt a declaration that nothing in SALT II will prevent the United States from continuing to help NATO countries with conventional and nuclear military assistance. The vote on this reservation, offered by Sen. Charles H. Percey, (R-Ill.), was 14 to 0.

The committee made this, in effect, a declaration of Senate attitudes. Before the 14-0 vote, it rejected two attepts to make this statement a formal reservation to the resolution of ratification that the Soviets would have to explicitly accept or acknowledge.

Lugar and Glenn were allied on this issue also, arguing the the United States should make the Soviets acknowledge this U.S. position to avoid any misunderstandings in the future.Adminstration officials and several other senators responded that it was a bad precedent to suggest to the Soviets that they have any say in U.S.-NATO relation, and further that the United States had made clear its intentions during negotiations with the Soviets.

During the negotations, the Soviets had pressed for a "non-transfer" clause that might have precluded U.S. transfer of potentially strategic weaponry to the NATO allies, but the United States would not accept this. Instead, the treat contains a "non-circumvention" provision declaring that neither side will circumvent its provisions "through any other state or states, or in any other manner." The United States contends that this only delcares an obvious fact of international law and has no consequences for U.S.-NATO relations.

An attempt by Lugar to force the Soviets to accept formally the U.S interpretation of the non-circumvention clause failed in the committee, 10 to 4. Glenn then suggested that at least the Senate give the Soviets formal notification of the U.S. position, but this was beaten, 8 to 6. The issue is likely to come up again on the Senate floor.

Glenn has a package of six proposed amendments related to monitoring the treaty, though he may not introduce them all. One would require both countries not to change the methods by which they send information on rocket test flights back to earth. Another would require them to agree with each other before encoding any of the radio messges ("telemetry") transmitted to earth by a test rocket.