KW - 7 Orestes |
KW-7's saw service in three variants. The original version used wire cords to set the daily key. Next, the plugblock version was introduced while the last variant used a paper card reader. Externally, one could tell the machines apart by the front covers. The original version of the machine had a flat, front cover. When the plugblock version was introduced the cover had a small square bulge. When card readers were introduced, the cover shape changed to a large rectangular bulge.
Above: This is the card reader version of the KW-7. Below: The plugboard version. Both examples are on display at the Communications and Electronics Museum in Kingston, Ontario. (Photos by Jerry Proc) |
The Orestes cryptosystem employed the KW-7. It was an on-line, send/receive crypto unit installed in shore stations and aboard ships. In one application, it was used for ship to shore and for intership radioteletype communications. To send messages over a secure UHF teletype circuit, a model 28 Teletype or reader (T-D) sent the prepared message to the KW-7 which in turn keyed a UHF transmitter in the AM mode. Note, that the KW-7 was not a totally synchronous unit, therefore, it required a phasing signal to be sent in order to attain a lock on the received signal. top. The circuitry was all solid-state and fit in a fairly rugged housing that featured a Tempest-sealed lid on top, removable for servicing. The KW-7 was also used aboard aircraft such as EC/RC-135's.