NEW YORK, April 25--A group of Tocsin members climaxed a demonstration in front of the Soviet legation here this afternoon by presenting embassy officials with a letter to Premier Khrushchev urging a more conciliatory attitude in atomic test ban talks.

Declaring that if current negotiations fail, "it is hard to see how others can have much hope of success," the letter urged the Soviets to negotiate "more flexibly" regarding three topics: the nature of the commission which would supervise the test ban, the number of inspections to be permitted, and the number of years before a control system could be put into effect.

No Soviet Concessions

While the United States has made a number of concessions during the current series of talks, the Russians have granted none, according to Robert E. Weil '61, the outgoing president of Tocsin. In addition, he noted the Russians have backed down on previous concessions.

They now want inspections to start four, instead of two years after the treaty is signed. They no longer agree to a control commission headed by a single neutral individual, similar to the U.N. Secretariat. The Soviets now demand a three man body. And they would allow only three veto-free inspections a year. The U.S. is asking for 17.

Before and during the delivery of the letter, 25 Tocsin members walked up and down a cordoned area down 69th Street from the Embassy, bearing signs reading "the Soviet Union in Challenged to Respond to recent U.S. test ban proposals," and passing out literature. Eighteen rather sympathetic policemen looked on, but at no time did an appreciable crowd gather.