A close aide to Montgomery County Executive Charles Gilchrist received a low-interest loan of $2,000 from a man whose relatives was seeking a job as deputy director of the county's Department Liquor Control, according to testimony heard in Rockville last night.

Charles Buscher, a former liquor company executive and Gilchrist campaign official, testified to the county's Personnel Board that he lent Gerard Evans $2,000 by a check dated Jan. 10, 1980, to help Evans with a house down payment. The loan carried 6 percent interest, Buscher said.

During 2 1/2 hours of testimony, Buscher told the board that Evans repaid the loan in cash in two installments in October and December last year, although some interest remained outstanding.

Montgomery County spokesman Charles Maier said this was the first public disclosure of such a loan. Buscher's testimony was part of a long investigation into allegations of tampering with the county's merit system in filling liquor department jobs.

County officials believe one of the probe's main concerns is how Frank Orifici, who is married to Busher's niece, obtained his job as deputy director of the liquor department. According to Orifici, he applied for the job in July 1979, was interviewed in January 1980 and began work in April 1980.

Gilchrist and Evans, who resigned his aide's job six weeks ago, have both testified to the Board in closed session. Neither was available for comment last night. Busher refused to give closed testimony, insisting he be heard in public, on the record, as he was last night.

Buscher said repeatedly that he had no recollection of ever discussing Orifici's hiring with Gilchrist administration officials before the selection was made.Although he did not know of Orifici's interest in the job before he applied, he did become aware that Orifici was on a list of those under consideration that had been narrowed to 25 names.

Buscher told the board that he met Gerard Evans during Gilchrist's campaign in 1978 and "I'd love to have him as a son." Buscher organized a surprise birthday party for Evans at the Potomac Inn restaurant in Rockville in December, he said. Among seven or eight persons present at the party were Orifici and the liquor department head, Robert Passmore.

Buscher and his lawyer told the board they would provide passbooks and deposit slips showing deposits into Buscher's bank accounts of the approximate amounts Evans gave him in repayment. Buscher said an IOU he had drawn up for the loan was returned to Evans when the loan was paid off. h

The Board asked Buscher whether he had known that Evans was lobbying for Orifici to receive the job. Buscher replied that he did not.

Evans quit his job with Gilchrist six weeks ago, sighting "pernicious innuendo" against him in connection with the liquor controversy. Evans is also alleged to have improperly offered jobs in the liquor department to consultant Leonard Colodny, which Evans has denied.

The personnel inquiry is one of three major investigations into alleged misdeeds at the county's $75-million-a-year liquor department.

Earlier this year an exhaustive audit by the private firm Touche Ross and Co. found mismanagement in the department but not favoritism in purchases from liquor wholesalers. Last month a grand jury wrapped up a seven month investigation of alleged bribery in the department without bringing any indictments.

The personnel board has no authority to bring criminal or civil charges. Many Gilchrist supporters expect its final report could severely criticize the executive. Gilchrist himself has maintained that an executive should be allowed to encourage qualified people to seek merit system jobs. Such encouragement.