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Professional covert radio bug
The Necktie bug was a professional crystal-based
miniature covert transmitter
built in the early 1990s by Mactron
in Oosterbeek (Netherlands). The
device was intended for body-worn use during covert and under cover
operations, primarily by government agencies such as the police.
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The Necktie bug received its name from the primary concealment it
was intended for. It was designed to fit inside the knot of a necktie
and was thought not to be discovered during a body search.
A thin wire of approx. 30 cm, acting as the antenna,
ran down the cloth of the necktie.
The unit was powered by a large 3V button-type CR-2430 lithium battery.
The image on the right shows the prototype of the nectie bug. It is built
inside a slim line metal enclosure with a separate compartment for the
battery.
The microphone with built-in pre-amplifier is at the front left.
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During an investigation, law enforcement agencies sometimes use
an under cover police officer or a 'turned' criminal as a bate, in the
hope that the prime suspect reveals incriminating details that can
be used as evidence during the investigation and in court.
In such cases, the bate often carries a concealed transmitter
and is then said to be 'wired' or to be 'carrying a wire'.
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It allows nearby police officers to eavesdrop
on the conversation whilst recording it, and take action if necessary.
Carrying such a wire is not without risk.
Criminals generally know they are being watched and will be extra
careful when talking confidentially. In such cases, the wired person is likely
to receive a body search.
The image on the right shows the transmitter nicely hidden inside
the knot of a necktie. In this case the wire antenna is sewed behind the
lining of the necktie, completely invisible to the naked eye,
in such a way that it is lined up vertically.
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The microphone is located at the top of the knot, in the ideal position
for picking up the conversation.
Due to its rather high position on the human body and the well-constructed
circuit, the necktie bug has a remarkably good operational range.
In combination with a high-end communications receiver it was possible to
cover a distance of more than one kilometer!
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The transmitter is housed in a slimline metal case which is 37 x 37 mm
in size and just 4 mm high. The image on the right shows the interior
of the necktie bug in which only miniature and subminiature components
are used. Most of the space is taken by the high-capacity 3V battery
that allowed eight hours of uninterrupted use.
The small electret microphone is located at the front left. The
frequency of the transmitter is determined by the crystal in the
top corner, that is used in the 3rd overtone. This example works at
a frequency of 154.050 MHz (51.350 x 3).
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The necktie bug was built in small quantities, exclusively for
law enforcement agencies, intelligence agencies and private investigators,
in The Netherlands and elsewhere. According to surviving
eyewitness stories, the necktie bug was used in a number of high-profile
undercover operations, but was never detected by criminals during a body search.
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© Crypto Museum. Created: Monday 29 April 2013. Last changed: Tuesday, 13 June 2017 - 07:09 CET.
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