B. F. Saul Real Estate Investment Trust reported yesterday a loss of $2.7 million (47 cents a share) for the fiscal year ending Sept. 30, 1979, compared with a 1978 loss of $4.9 million (84 cents).

For the fourth quarter, B. F. Saul lost $2.1 million (36 cents), compared with a loss of $1.1 million (20 cents) for the previous year.

The company also said its cash flow improved from a deficit of about $1.6 million in 1978 to a positive figure of $249,000 in 1979. The company attributed that change to a $2 million profit on its first condominium conversion.

B. F. Saul said its 1979 results were affected by continuing interest rate increases for its bank loans. The rate averaged 14.7 percent in 1979, compared to 10.5 percent in 1978. The currnet rate is 19.7 percent.

In other reports, Bowl America Inc. reported a loss of $57,650 (4 cents) for the first 13 weeks of its fiscal year. For the same period in 1978, the company reported a loss of $26,196 (2 cents) .

The loss, despite a 7 percent increase in gross receipts, was attributed to higher wages and food purchased for resale. In addition, Bowl America said tax considerations affected earnings but that those losses would be reversed later in the year.

Tech Serv Inc. reported a loss of $72,857 (13 cents) for the quarter ending Sept. 30, compared to a loss of $6,965 (one cent) for the same quarter last year.

The company's sales for the quarter were $296,009, compared to sales of $777,650 for the quarter ending June 30, 1979. The company's decrease in sales was attributed to completed contracts for aerial targets.

Biospherics Inc. reported profits of $225,168 (16 cents) for the nine-month period ending Sept. 30, compared with profits of $184,333 (13 cents) for the same period last year.

PPH Group Inc. reported six months profits of $7.9 million ($1.29) for the period ending Oct. 31, compared with profits of $5.6 million (92 cents) for the same period in 1978.

Computer Network Corp. reported profits of $371,000 (22 cents) for the quarter ending Sept. 30, compared with $248,000 (15 cents) for the same period in 1978.