Reflecting a positive cash flow from operations, the B.F. Saul Real Estate Investment Trust reported yesterday that its net loss was sharply reduced in the first fiscal quarter ended Dec. 31.

Saul's net loss for the period was $740,000 compared with a loss in the same period the prior year of $1.7 million.

The real estate trust, largest in the Washington area, said cash flow before mortgage principal payments was $490,000 in the October-December quarter compared with a deficit of $479,000 a year ago.

Saul attributed this turnaround to profits on a condominium conversion and to continued improvement in the returns on income-producing properties. This was partially offset by an increase of 4 percentage points in interest rates applied to the trust's bank loans.

Bowl America, a Springfield-based owner of bowling centers, reported profits in the second quarter ended Dec. 31 of $403,132 (29 cents a share), down slightly from $420,461 (30 cents) in the 1977 period.

For the six months ended Dec. 31, Bowl America's earnings dipped to $370,903 (27 cents) from $422,866 (30 cents) and revenues edged higher to $6.31 million from $6.3 million. Unusually warm fall weather delayed the start of the traditionally stronger winter-season bowling business.

AP also reported the following :

A.H. Robins Co. reported net earnings of $29.9 million ($1.15 a share) for 1978, up 12 percent over 1977 earnings of $26.8 million ($1.03).

For the last quarter of 1978, the Richmond-based pharmaceutical manufacturer reported net earnings of 22 cents a share, down 19 percent from the same three-month period in 1977 although sales were up 14 percent to $95.5 million.

President F. Claiborne Robins Jr. attributed the decline in fourth-quarter earnings to foreign exchange losses and higher costs of litigation. The litigation was in suits filed against Robins by users of its now-discontinued intrauterine device, the Dalkon Shield, and the firm's antitrust suit against Hartz Mountain Corp. filed last April.

Sales in 1978 were $357 million, 16 percent above sales of $306.7 million for 1977, Robins reported.

Worldwide sales of health-care products accounted for the major portion of the company's 1978 sales increase, Robins said.