A polygraph expert testified in a Senate hearing yesterday that a former aide to Sen. Herman E. Talmadge (D-Ga.) told the truth when he said Talmadge received funds from a secret bank account containing illegal Senate expense reimbursements and campaign contributions.

Raymond J. Weir, a former polygraph (lie detector) expert for the National Security Agency who now heads his own private polygraph firm here, said he tested Daniel Minchew, a former chief aide to Talmadge, April 4 this year at the request of Minchew's attorneys.

Weir said Minchew truthfully answered six questions indicating that he gave Talmadge money from the secret account on at least two occasions-in Talmadge's office and in the lobby of the Embassy Row Hotel here. Weir said Minchew also told the truth when he said another Talmadge aide, Allyne Tisdale, helped him convert campaign funds for Talmadge's personal use.

Minchew has been tested at least three other times by polygraph experts. Two tests by the FBI in January indicated he was lying when he said Talmadge knew of the secret account at the Riggs National Bank here, sources said. A test by another nationally known polygraph expert hired by Minchew's attorney's indicated he was telling the truth about the same question.

Weir testified yesterday before the Senate Select Committee on Ethics, which is conducting its second week of hearings into five allegations of financial misconduct against Talmadge. The most serious of the charges are that Talmadge knew of improper Senate reimbursements for his office expenses and that he used the secret account at the Riggs National Bank here in 1973 and 1974 to convert campaign contributions to his personal use.

Minchew has told the committee he set up the secret account and ran it while he was Talmadge's chief aide. But he said Talmadge knew of the account and benefited from it. Talmadge has responded by calling Minchew "a proven liar, cheat and embezzler" and denying any knowledge of the account.

In his opening statement to the ethics panel last week, Talmadge told the committee that his attorneys would prove Minchew failed three FBI lie detector tests and was deceptive in his answers to his own polygraph expert. But so far neither Talmadge nor his attorneys have offered any indication of what evidence they have to support those allegations.

Weir said that Minchew had truthfully answered the following questions:

Questions: "In late 1974, after you left his staff, did you hand over cash from the secret Riggs account to Senator Talmadge in the lobby of the Embassy Row Hotel?"

Answer: "Yes."

Question: "Did you and Mrs. Tisdale at any time work together in converting campaigns funds to cash for Senator Talmadge's personal use?"

Answer: "Yes."

Question: "Did you ever supply cash from the secret Riggs account to Senator Talmadge in his Senate office?"

Answer: "Yes."

Question: "Other than five- or ten-dollar contributions, did any staff member, other than yourself, know of cash contributions made directly to Senator Talmadge, some of which were not reported?"

Answer: "Yes."

Question: "Did anyone else on Senator Talmadge's staff ever aid in converting campaign funds to cash for Senator Talmade's personal use?"

Answer: "Yes."

Question: "Did Senator Talmadge ever refuse to accept the cash you provided him?"

Answer: "No."

Weir, a former director of internal security for NSA, said that during his career he had administered more than 5,000 polygraph examinations and supervised 50,000 more. Less then one-half of 1 percent of the tests turned out inaccurate, he said.

Asked by committee attorney Douglas McCullough about Minchew, he said: "The man, in my judgment, is telling the truth [in response] to these particular questions."

The polygraph expert said the FBI's tests are conducted using another method known as the "control technique." He said he uses a procedure known as the "relevant-irrelevant" technique. Both are accepted polygraph procedures, he said. CAPTION: Picture, Witness Raymond Weir: "This man, in my judgment, is telling the truth. . . ." By James K. W. Atherton-The Washington Post