Jacob T. Nemerow, 84, an electronics engineer who retired in 1984 from the Naval Air Systems Command and then learned to play several fretted instruments and became a professional musician, died of cancer Dec. 27 at Potomac Hospital. He lived in Woodbridge.

Mr. Nemerow was a native of New York who served in the Army in Europe during World War II. He attended Youngstown State University and St. Mary's College in Maryland and received a bachelor's degree from the University of Maryland.

He worked for Pan American Airlines and Philco as an electronics technician and went to work for the Naval Air Test Center at Patuxent River in 1958. He was later an avionics system project officer for the F-4 series and representative of the systems and engineering directorate to the Component Configuration Control Board of the Air Systems Command.

After he retired, he learned to play instruments that included the balalaika, string bass and bass guitar. With the Takoma Mandoliers and the International Music Makers, a group headed by his wife, Rosa Nemerow, he played in restaurants and other venues. He also appeared at the Kennedy Center, Carnegie Hall, Lisner Auditorium and in Russia and elsewhere in the United States.

Mr. Nemerow was a member of the Washington Balalaika Society Orchestra, Fretted Instrument Guild of America, Balalaika and Damra Association, B'nai B'rith, National Association of Retired Federal Employees, AARP, Arlington-Fairfax Jewish Congregation and the Elks.

His military honors included the Bronze Star.

In addition to his wife, of Woodbridge, survivors include three sons, Stanley Nemerow of Charleston, W.Va., Larry Nemerow of Manassas and David Nemerow of Dumfries; a brother; a sister; six grandchildren; and a great-grandchild.