B.F. Saul Real Estate Investment Trust, Biospherics Inc., Input Business Machines Inc. and Universal Security Instruments Inc. all have reported losses, while Washington Real Estate Investment Trust posted improved profits for the latest quarter.

The recession was blamed for cutting condominium sales of the Saul REIT, slowing burglar and fire alarm business at Universal Security, and holding up new government and industry contracts for Biospherics.

Biospherics Inc., based in Rockville, said first-half revenues dropped 19 percent to $2.39 million from $2.96 million, producing a loss of $92,900 (5 cents a share) compared with a net profit of $57,000 (3 cents) in the same period a year ago.

For the second quarter, Biospherics lost $44,900 (3 cents) on revenues of $1.2 million in contrast with a profit of $41,200 (2 cents) on revenues of $1.5 million last year.

Input Business Machines Inc., a maker of optical character readers that translate printed words into computer language, posted a profit of $51,000 (3 cents a share) on revenues of $1.13 million for its second quarter, a gain over the earnings of $34,700 (2 cents) on revenues of $876,000 last year.

But for the first half of 1982, Input lost $185,000 (9 cents) on revenues of $2.15 million compared with a profit of $128,000 (9 cents) on revenues of $1.7 million in the first half of last year.

Universal Security Instruments Inc.'s loss for its first quarter ended June 30 amounted to $295,000 (12 cents a share) compared with a profit of $267,000 (11 cents) in the same period a year ago. Sales slipped slightly to $4.4 million from $4.8 million because of what the company called "deteriorating national economic conditions."

B.F. Saul Real Estate Investment Trust said its operating loss increased to $557,000 (9 cents a share) from $352,000 (6 cents) for its third quarter ended June 30, and the loss for the first nine months of its fiscal year amounted to just over $4 million (67 cents) compared with a profit of $4.8 million (82 cents) in the same period a year ago.

Cash flow from operations -- sometimes regarded as a better indicator of performance for real estate companies -- dropped to $1 million from $1.23 million for the year-ago quarter and amounted to only $3,000 for the year to date compared with $10.6 million in the first nine months of 1981.

In contrast to the Saul trust's loss, the smaller Washington Real Estate Investment Trust reported that its net income increased for both the second quarter and first half of the year. For the quarter, Washington REIT earned $1.3 million (27 cents a share), up from $1.2 million (25 cents) a year ago. First-half net income climbed to $2.3 million (48 cents) from $2.1 million (44 cents). President B. Franklin Kahn said the office building earnings improved because rents were raised.