KW - 26 |
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GENERAL
The KW-26 was used by U.S. /NATO intelligence services to provide point-to-point 100 wpm circuits for expeditious transmission of highly compartmented information. Only the keying material differed from that issued to operational units. Each circuit had a scheduled re-key time every 24 hours called BRAVO INDIA (BI), a process specific to the KW-26. It was used prior to HJ (HOTEL JULIET). However, in the early 60's, most long haul communications were via radio propagation which was subject to many forms of interference both man made and natural. Since the receiving unit could only tolerate a bias distortion rate of about 25-26%, many circuits were constantly dropping synchronization, thereby necessitating many re-key/re-starts daily. Since most of the circuits were long haul and ciphony was not yet prevalent, the circuit stayed in the clear until a restart could be accomplished. VARIANTS: - First unit delivered in 1957 [1] -A First version - At one time the NSA Communications Center had 336 KW-26's in operation. [1] RECEIVER vs TRANSMITTER DIFFERENCES The KW-26 receiver and transmitter look nearly identical, however there were two differences. Ken Sutterfield explains " Transmitters did not have Phase Indicators, they had a transmit light. The "C version of the transmitter also had an alarm test switch located above the meter on the left side of the front panel. It was similar to the meter switch located below the meter". The 'B version of the transmitter had the Alarm test switch mounted internally. Doug Eyre explains. It was on the A7 panel on the left side. We had to open the equipment to perform the alarm check. As I recall, the alarm switch was "hidden" because outsiders were not to know how many alarm positions there were (14, I think). We were supposed to check each position and clear the alarm with the switch. But the last position should not have been able to be cleared. Alarm checks were perfunctory at best". KW-26A
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