“I define myself as a journalist,” he once told the Israeli newspaper Haaretz, “but first of all as a patriot.”
In 1974, he was credited with helping to save the life of Archbishop Makarios III, the president of Cyprus, after he was deposed in a bloody military coup. Archbishop Makarios was presumed dead, but Mr. Gurdus overheard his appeals for assistance from a makeshift transmitter and alerted the British authorities, who rescued him.
During the Watergate scandal in 1974, he intercepted a White House phone call to Alexander M. Haig Jr., President Richard M. Nixon’s chief of staff, who was on Air Force One as it flew over the Middle East. The White House was calling to say that the Watergate special prosecutor was on his way to retrieve potentially incriminating tape recordings of Oval Office conversations from “the red safe.”
“We just don’t want anyone to have access to any tapes,” Haig was heard saying. “Anyone.”
Mr. Gurdus, perpetually sporting earphones and often sifting gibberish and static, listened in on a litany of, well, signal events. He overheard and revealed Operation Tshura, in which Israeli forces destroyed 14 Arab airliners in Beirut in retaliation for terrorist attacks on El Al planes. He got wind of a secret Soviet airlift of weapons to Egypt in 1970.
He also picked up on the hijacking by Palestinian terrorists of an Air France plane to Entebbe, Uganda, in 1976; an abortive United States attempt to rescue hostages from the American Embassy in Tehran in 1980; Saddam Hussein’s invasion of Kuwait in 1990; and a devastating earthquake in Haiti in 2010.
During the 1973 Yom Kippur War, when Arab states attacked Israel, Mr. Gurdus helped identify captured Israeli paratroopers by lifting their images from Egyptian television.
In 1977, an Israeli radio station prematurely broadcast his tip that German forces were on their way to recapture a Lufthansa plane that had been hijacked to Somalia. The rescue mission could have potentially been jeopardized by the report, but it succeeded.
Mr. Gurdus said he was not pleased by the leak.
“Whenever I have information that could jeopardize human lives,” he said, “I do not publish it.”
In 1984, he overheard Shiite Muslim hijackers executing one hostage and beating others after they had commandeered a Kuwaiti plane.
“I could hear the screams as they tortured the hostages and threatened to execute them,” he told The Christian Science Monitor in 1985. “It was the most awful thing. I sat here shaking.”
Michael Gurdus (who was known as Mickey or Micki) was born on Nov. 9, 1944, in Tel Aviv. His father, Nathan, who used a wheelchair because of a crippling childhood illness, was living in Warsaw when he began monitoring Eastern European radio broadcasts and Morse code communications for a London newspaper in the mid-1920s.
Nathan Gurdus and his wife, Irene, fled Warsaw as the Nazis invaded in 1939 and settled in Israel, where he joined the Irgun, the militant Zionist group. He later became a correspondent for Agence France-Presse.
Their son was still in high school when he, too, discovered his calling. “I was my father’s legs,” he told People magazine in 1982. “He was my teacher.”
Mr. Gurdus later studied Orientalism and political science at the Hebrew University in Jerusalem.
His survivors include his second wife, Bilha; three daughters; and several grandchildren.
Mr. Gurdus conducted his eavesdropping vigils, up to 18 hours a day, for most of his life from a 10-by-12-foot room in the second-floor Tel Aviv apartment where he was born. The room, festooned with photographs and postcards, was a jungle of tangled wires. The building’s roof was forested with aerials and satellite dishes.
He knew Hebrew, English, Arabic, French, Russian and Polish, which helped him remain Israel’s ears even as the internet and other communications advances might have rendered him obsolete. But he did not know much about electronics.
“I do not understand anything about technology,” he once said. “If a device ever breaks, I call a technician.”
He did not drive or fly and rarely took vacations during a life crisply defined in a magazine profile decades ago.
“There were two major events in Michael Gurdus’s life this year,” the profile began. “He acquired a new wife and a new antenna — both beauties.”