John M. Dunnam, 69, a radio technician in Washington for more than 50 years, died of a heart ailment Thursday at Holy cross Hospital of Silver Spring.

Mr. Dunnam was taught radio engineering by his father, the late Lawrence M. Dunnam's and in 1937, they opened Dunnamhs Radio Service in downtown Washington. During World War II, the business was suspended while Mr. Dunnam worked as a radio technician on military aircraft at National Airport for the Pennsylvania Cnetral Airlines. After the war, he reopened the business until dissolving it in 1957, when he became a radio technician for American Airlines. He retired in 1971 for medical reasons.

Dr. Dunnam was born in Salen, Va. and moved here with his family at an early age. He graduated from old Central High School.

In January 1922, Mr. Dunnan and a sister escaped without unjury in what is considered to be Washington's worst disaster, the collapse of the roof of the old Knickerbocker Theater at 18th Street and Columbia Road NW. Ninety-eight people were killed and 136 injured when the roof of the theater fell under the weight of 2l inches of snow during one of the city's worst snowfalls.

Mr. Dunnam lived in Silver Spring and was active in the St. Stephen and the Incarnation Episcopal Church in Washington and in the Church in Silver Spring. He was a member of Lebanon Lodge No, 7 of the Masons.

His first wife, Hazel, died in 1968.

Survivors include his wife, the former Helen Sallust, and a son, Nelson L., both of the home; a daughter, Virginia E. Pinto, also of Silver Spring, and two granchildren.

The family suggests thjat expressions of sympathy be in the form of contributions to the John M. Dunnam Memorial Fund, Church of Our Saviour, Silver Spring.