Scope Inc. of Reston reported a net loss of $431,000 (35 cents a share) on revenue of $3.5 million for its second quarter, sharply up from its loss of $56,000 (5 cents) on sales of $3.5 million for the same quarter last year.

Timothy J. Crowe, acting president and chief executive officer at Scope and executive vice president and chief financial officer of Lexicon Corp., blamed the problems on Scope's unsuccessful attempt to fight off Lexicon's takeover bid.

Lexicon gained control of Scope on June 27. Scope specializes in computer and signal-processing technology, while Fort Lauderdale, Fla.-based Lexicon manufacturers computer terminals and equipment for electronic signal processing.

For the first six months, Scope lost $571,000 (47 cents) on sales of $7 million, compared with a $202,000 (17 cents) loss on sales of $6.2 million for the 1984 first half. The company said it already has implemented an "aggressive action plan" to reduce expenses.

*Computer Network Corp. reported net income of $52,400 (2 cents a share) on revenue of $8.7 million for its first quarter ended June 30, the first time this quarter has been profitable in six years. The company lost $538,000 (28 cents) on sales of $1.8 million in the comparable period last year.

The Washington-based computer firm said earnings would have been stronger, but spending for the development of its new software product, EZ-Word, and a nonoperating loss of $50,400 cut into profits.