A stunning slowdown in condominium sales caused B.F. Saul Real Estate Investment Trust to report a loss of $2.4 million (58 cents a share) for the first three months of 1982, in contrast with a $1 million (59 cents) net profit in the same period a year ago.

Condominium sales for the quarter dropped from $7.7 million to $1.4 million and were down to $3.1 million from $23.4 million for the six months ended March 31. For the six months, the Saul REIT lost $3.5 million (38 cents) compared with a profit of $5.2 million (9 cents) in the first half of the previous fiscal year.

Condo conversions had produced a $3.5 million profit in the first three months of 1981, but yielded a slim $26,000 profit this year. For the first half, the trust lost $20,000 on condominium conversions, compared with a $10.8 million profit in the first six months of fiscal 1981.

Chairman B.F. Saul II said the "downturn was caused by a reduction in condominium profits," adding that "income producing properties have continued to perform well considering the adverse trends in the economy."

Despite the losses, the Saul REIT declared its regular quarterly dividend of 5 cents per share to be paid July 15 to stockholders as of July 1.

For the year ended March 31, Universal Security Instruments Inc. of Owings Mills, Md., posted record sales of $18.5 million, a 37 percent increase over $13.6 million last year.

Plant expansion, research and development cut into profits, however, company officials said. Earnings for the year dipped to $59,785 (2 cents a share) from $664,074 (28 cents) a year ago. During the fourth quarter, the company recorded a net loss of $225,479, compared with earnings of $195,370 (9 cents) in 1981. Revenues increased 17 percent to $4.9 million from $4.2 million.

Schluderberg-Kurdle Co. Inc., makers of Esskay franks and other processed meats, rebounded in the second quarter from its loss a year ago to post profits of $26,000 (3 cents). For the comparable period of 1981, the company lost $587,000.

Revenues in the latest quarter increased to $34.4 million from $30.2 million. Sales for the half increased to $66.2 million from $61.2 million.