The 700 lb B61 is the only tactical nuclear bomb in the U.S. arsenal. ... the right altitude to explode; it is an old model that still uses vacuum tubes.
$8 billion upgrade to the B61 nuclear bomb.
B61 bombs that have vacuum tubes in their radar-fuses account for only about one in ten operationally deployed warheads
Engineers have resorted to scouring EBay to replace circuits and vacuum tubes to keep the bombs operational.
B61 nuclear bomb - Wikipedia, the free encyclopedia
WikipediaThe B61 nuclear bomb is one of the primary thermonuclear weapons in the U.S. Enduring Stockpile following the end of the Cold War. It is an intermediate-yield ...
Blast yield: 0.3–340 kilotons
Designer: Los Alamos National Laboratory
Used by: United States
B61 Family - Wikipedia, the free encyclopedia
WikipediaJump to Bomb - Bomb. The overall B61 bomb was 13.3 inches (340 mm) diameter by 141 inches (3,600 mm) long, and weighed 695-715 pounds ...
From PBS News Hour