John Milton Whitman, 78, a retired radio and television engineer who was assigned to presidential broadcasts from the White House during the 1940s when he worked at station WTOP, died Thursday at the Bishop McCarthy Residence, a nursing facility in Vineland, N. J. He had lived in Manassas until moving to Vineland two months ago.

Mr. Whitman was born in Everett, Wash. His father was a U.S. Marine officer, and he grew up in Montana, the Dominican Republic and Haiti. When he was 16, he joined the merchant marine and began his career as a radio operator and engineer.

He worked at radio stations in New York, New Jersey and North Carolina. In 1939, he moved to Washington and was an engineer at the CBS affiliate, WTOP, now WJLA. He remained there until 1948. During those years he was the CBS engineer assigned to broadcasts by presidents Roosevelt and Truman.

Mr. Whitman later owned and operated a radio station in Vineland, worked for CBS in New York, where he developed a device for focusing television cameras, was an engineer for the Voice of America in Portugal, and was a private consulting engineer in Singapore, Vietnam and Iran.

In 1968, he returned to the Washington area and was an engineer at WNVT in Northern Virginia until his retirement in 1974.

Mr. Whitman was a member of the National Brotherhood of Electrical Engineers.

Survivors include his wife, Agnes Cardinale Whitman, whom he married in 1927, of Vineland; five daughters, Mrs. John Leddo of Bridgeport, Conn., Mrs. John Montrose and Mrs. Edward Steelman, both of Vineland, Rosita Whitman of Middleburg, Va., and Mrs. John Hectus of Gillette, N. j.,; one son, Richard, of Sebastopol, Calif.; 11 grandchildren, and three great-grandchildren.

The family suggests that expressions of sympathy be in the form of contributions to the American Cancer Society, or to the American Diabetes Association.