Detail of a strapped cavity Magnetron from the WWII
display. The circle of resonant cavities can be clearly
seen as can the wire “strapping” the cavities.
Earlier unstrapped magnetrons tended to be unstable-
they would go off frequency. Strapping cured this
Credit for the successful development of the Magnetron
goes to Randall and Boot of Birmingham University.
Without the vital equipment, the outcome of the Second
World War could have been very different.