Perpetual American Bank, the largest thrift institution in the area, reported that earnings nearly doubled in its fiscal 1986 second quarter that ended April 30.

Meanwhile, Iverson Technology Corp. and Washington Homes Inc. posted quarterly gains in earnings, while B. F. Saul Real Estate Investment Trust and QuesTech Inc. posted quarterly losses.

Perpetual, which is based in Alexandria, said it earned $6.1 million (75 cents a share) compared with $3.3 million (49 cents) for the second quarter of fiscal 1985.

Last year's second-quarter net income was boosted by a one-time tax credit of $846,000, which added 12 cents a share to earnings, Perpetual said.

The second-quarter results bring the thrift institution's earnings for the first half of fiscal 1986 to $10.7 million ($1.29).

In fiscal 1985, earnings in for the first six months were $8.5 million ($1.25).

*Iverson Technology Corp. announced earnings increased 3.7 percent on an 18.4 percent increase in revenue for the first quarter of 1986.

The computer-products company, which is based in McLean, said net income was $438,465 (18 cents a share) on revenue of $4.5 million.

Earnings were $422,684 on revenue of $3.8 million for the first three months of 1985, the company said.

Iverson said the quarterly results include earnings and revenue for its subsidiary, International Technology Corp.

*Washington Homes Inc. of Waldorf said earnings increased 171 percent on a 64 percent in sales for the third quarter of its fiscal 1986.

Earnings for the three months that ended April 30 were $1.9 million (65 cents a share) on revenue of $19.9 million. Earnings for the same period last year were $676,607 (25 cents) on revenue of $12.1 million. The results bring the company's earnings for the first nine months of fiscal 1986 to $5.1 million (1.79) on sales of $54.4 million. Earnings for the first nine months of fiscal 1985 were $2 million (75 cents) on sales of $42.3 million, the company said.

*B. F. Saul Real Estate Investment Trust of Chevy Chase said it lost $6.1 million ($1.12 a share) in the second quarter of its fiscal 1986, about double the $2.8 million (50 cents) it lost for the same period last year.

The quarter's results bring the loss for the six months that ended March 31 to $9.9 million ($1.80) compared with a loss of $4.2 milion (74 cents) for the same period last year.

*QuesTech Inc. of McLean reported a loss of $260,806 (17 cents a share) on revenue of $10.8 million for the first three months of 1986.

The company, which provides engineering and other science services, earned $79,890 (5 cents) on revenue of $9 million for the first quarter of 1985. The company said its losses stemmed from the DEI-West Division of its subsidiary, Dynamic Engineering. The losses were caused by contracts that were bid too low, the company said.