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USA NSA Voice NESTOR ← KY-8
The image on the right shows a US soldier with an
PRC-77 manpack radio
on his back, during the Vietnam War in October 1969. Below the radio set is
the KY-38 voice encryption unit, which is about the same size as the radio
itself.
The handset is connected to the KY-38, while the KY-38
is connected to the 14-pin socket of the radio, via a long thick cable.
This cable provides the KY-38 with power, whilst connecting the
input and output of the device directly to the transmitter and receiver
circuits, thereby effectively bypassing the audio circuits of the
radio.
The radio provided excellent security but was nevertheless hated by its
operators. The audio quality was not very good and the total weight was close
to 25 kg. Furthermore, there is a 600 ms synchronisation delay each time the
push-to-talk switch is pressed. In addition, the device was running hot
in the burning Vietnamese sun, prompting technicians to cover it with wet
cloths and drill unauthorised holes in the enclosure to provide sufficient
cooling and avoid break-down.
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The KY-38 was introduced in 1967, together with the airborne KY-28
and shortly after NESTOR member KY-8.
They were first used in the Vietnam War and were initially
only available in small numbers. In 1974, the KY-38 was succeeded by
the KY-57 (VINSON).
The last NESTOR units were decomissioned in the early 1980s.
In total, approx. 30,000 NESTOR devices were produced.
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The Vietnam War lasted from 1 November 1955 to 30 April 1975.
➤ Wikipedia
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Photograph of soldier with
PRC-77 and KY-38
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The photograph above was obtained via Wikipedia,
where it is attributed to the
NSA [4]. Note however, that the image as supplied by the NSA is
mirrored horizontally,
showing the controls and connections of both devices
in the wrong position. The above version has been corrected.
The image above appears to be a cut-down version of
this photograph, in which the entire
antenna and the soldier's feet are fully visible.
According to the caption at the back of the photograph,
it was made in Vietnam on 16 October 1969 by SP4 Timothy F. Fease.
It was released for publication on 30 january 1070.
Interestingly, the cover of the technical manual of the KY-57
— the successor of the KY-38 — shows a drawing of a soldier in the exact same
position, but with a KY-57 strapped to the harness instead of the KY-38.
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The AN/PRC-77 radio
was in fact a PRC-25
that had been given a solid state RF power amplifier, and
was modified for the connection of
digital voice encryption equipment,
by adding a so-called X-MODE to the circuitry.
When in X-Mode, the filters in the audio path of transmitter and receiver are
bypassed so that the full bandwidth of the set can be used.
➤ More about the PRC-77
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Device Wideband voice encryption device Purpose Secure military communications Model KY-38 Year 1967 Family NESTOR Country USA Successor KY-57 Encryption ? Modulation ?
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Declassified by USAPA, 30 January 1970.
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© Crypto Museum. Created: Saturday 01 October 2016. Last changed: Wednesday, 01 May 2024 - 06:54 CET.
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![US soldier in Vietnam operating a PRC-77 radio with KY-38 voice encryptor. 16 October 1969 [2].](img/ky38_soldier_large.jpg)
