American first purple analog 1

The first analog to the Purple machine (w:Type B Cipher Machine) reconstructed by the US Signals Intelligence Service. The unit contains fourteen 6x25 steping switches. A hand-operated Red analog is also visible. The note to the right describes how a relay welded shut during the Purple unit's first trial and how adding a capacitor fixed the problem. (Pictures taken by Mark Pellegrini at the US National Cryptologic Museum.)