KDI <KDI> TO BUY TRIANGLE MICROWAVE <TRMW> KDI Corp said it has agreed in principle to acquire Triangle Microwave Inc for 6.50 dlrs plus a contingent payment for each Triangle share. It said holders of the contingent payment units will be entitled to receive annual payments to the extent that the predepreciation gross profits of Triangle Microwave in each of the years 1987 through 1991 exceed threshholds ranging from eight mln dlrs in 1987 to 14 mln dlrs in 1991. The company said holders of Triangle Microwave options and warrants will be entitled to receive the difference between 6.50 dlrs and their exercise price, plus contingent payments. KDI said completion of the transaction is subject to governmental approvals and the approval of Triangle Microwave shareholders, and the transaction is valued at over 35 mln dlrs. It said shareholders of Triangle Microwave controlling about 30 pct of the company's stock have agreed to vote in favor of the deal and to give KDI an option to buy their shares under certain components. Triangle Microwave makes microwave components. KDI, a diversified company, produces electronic components, technical products and swimming pool equipment.