Yaakov was born on October 4, 1924 in what is now the city of Brest, Belarus, a lone child to Shoshana (daughter of Rabbi Wurzburg from Lublin) and Rabbi Moshe Noah Flavsky, descendant of the Kobriner Rebbe, head of the Kobriner Hasidic sect. In 1933, at age nine, his family made aliyah and settled in Tel Aviv. Yaakov studied in the Tachkemoni, Halperin and Moriah Schools, as well as the Montefiore High School, where he studied electronics and radio. He also studied turnery at Max Pine.

In 1937, he joined Beitar, and in 1940, IZL. When the split occurred, he followed Yair to Lehi, convinced that removing the British was the only way forward. After Yair’s murder and the difficult organizational crisis, Yaakov decided to join the Palmach “until the wrath will subside.” There he underwent military training. He returned to Tel Aviv and joined Tuvia’s group, which was temporarily discrete from Lehi in order to thwart any informers on the eve of war. After Yitzhak “Michael” Shamir escaped from Mizra and Lehi was reorganized, Yaakov returned to full duty.

Yaakov was charged with instructing the new trainees in ideology and the dissemination of promotional materials. He gathered intelligence and investigated, making connections with police sources, cabdrivers, nightclubbers and others. Throughout this time, he worked at a factory as a cover for his activities, allowing him to acquire arms and materiel. He also took part in publishing the underground periodical HeHazit. One of the new roles he was assigned was setting up a Lehi radio station, which began broadcasting in 1945 in Naomi and Avraham Bash’s apartment in Ramat Gan.

In February 1946, the British caught them, as they were broadcasting from a house at 3 HaShomer Street in Tel Aviv. Yaakov was sent to Jaffa Prison, then imprisoned in Latrun and Jerusalem, and finally exiled to Eritrea. He returned only in July of 1948, with the last group of prisoners. He joined the fight with Lehi in Jerusalem, establishing the communications network.

After the Bernadotte assassination, he enlisted in the IDF, at first in the Communications Corps and afterwards in the General Staff Communications Company, where he helped establish Army Radio.

After being demobilized, he worked as an electronics technician. He loved radios and computers, and he was one of the founders of the Israeli Amateur Radio Club, in which he played central roles. He was even its honorary president.

He married Zvia Ribnick. They had three children and numerous grandchildren