Myrtle Phillips nearly dropped her grandson when she turned on a local talk show this afternoon and learned that President Carter had granted an unconditional pardon to Vietnam draft evaders. Her son Ron would be coming home from Canada for the first time in six years.

"I couldn't believe I had heard the report correctly," she said as the excitement in her voice rippled through the telephone wires. "For the first time in such a long time my son will not be a criminal in the eyes of society."

Mrs Phillips turned on the radio to confirm the report and then she called the Justice Department. "I just wanted to know when the pardon would take effect," she said, "I told them, 'don't be shuffling those papers too long.'"

Her son, she explained, is coming home to Arlington in February for a few weeks to see his family and to fake the measure of the Washington job marked. Mrs. Phillips wanted no mistakes made at the border when he crossed.

For Mrs. Phillips, the pardon came at a time when she feared she might lose her son permanently to the war's bitter legacy, Ron, she said, has a good job now as a counselor to runaway children in Winnipeg, and "if it had gone on much longer we would have had to make the decision that Canada was his home and put doun some roots." Already, she said, his girlfriend Joan had moved to Winnipeg to be with him, and slowly, it seemed, his exile was becoming a permanent one.

Mrs. Phillips' joy, however, is tempered by her commiseration for the mothers whose sons had decided against the war after - rather than before - they were inducted. Deserters as well as evaders, she belives, should be pardoned, "There are mothers who should be just as happy as I am today," she said. "Suppose we could't have afforded to send our son to college," she said. "What are the chances that he would have been a deserter?"

It was the night after Mrs. Phillips' son's graduation from Southwestern College in Winfield, Kan., in fact, that he came to them and showed them first his diploma and then the draft notice. Nine months later, in March, 1971, he left for Canada. She and her husband admired him for his decision, she said, but they didn't try to influence it. "We sent him away to college to think for himself and that's what he did," she said.

But then came the aftermath of the decision - the annual visits from the FBI, the neighbors who scorned them, the feeling of isolation once the war ended but their own struggle did not. The Phillip's saw their son twice on summer visits to Canada, but after she and her bushand had both had cataract operations, said Mrs. Phillips, "we weren't sure whether we would ever be able to make another trip."

Last night, Mrs. Phillips planned no joyous celebration in honor of her son's return. "I'm going to the cathedral," she said. "To get down on my knees."

The news of the pardon brought a different reaction to Nancy Montgomery. Her son is a deserter who has lived for the last six years in Vancouver.

"My first reaction was just rage," she said in a telephone interview from her home in Glover Park. "I really hoped the war was over. I hoped that people could forget.

Her son, 29 has a new life now and a new name, Morgan O'Neil. But in 1970, he was Howard Montgomery, a conscientious objector in Ft. Collins, Colo., with only six months left to go when the Army ordered him to Vietnam. "Her came home," said Mrs. Montgomery, the memories fresh in a voice that seemed to the fighting back the tears. "Then he left the country."

They had been close, said Mrs. Montgomery, not only in the love of mother and son, but in the hatred for the war that took them to peace marches together. She feels that it was her son's decision to continue his antiwar efforts as a conscientious objector that induced the Army to send him to Vietnam.

Her son had thought of evading the draft rather than becoming a conscientious objector, she said. "The night before he had to go for his induction, we sat up all night trying to decide whether he should leave for Canada instead," said Mrs. Montgomery. "But he decided to go through with being a conscientious objector because it wouldn't be as hard on the family."

For that reason, Mrs. Montgomery said, she couldn't understand why the draft evaders have been pardoned and the men like her son have not. "I'm happy for the ones who can come home," she said. "But there shouldn't be any difference. The evaders just deserted before the fact instead of after."

After the war ended, Mrs. Montgomery said, "people would ask me. 'When is your son coming?' They would be suprised when I told them he couldn't come home."

Now, with the news of the pardon, Nancy Montgomery has little hope, and only question. "When are they going to let us put it all behind us?"