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CIA FBI AID ← Unitel 225
The device measures 93 × 57 × 18 mm and weights 162 grams, batteries included.
It has rounded corners and could easily be hidden under the clothing. In
practice, the device was often worn in a special harness or taped to the body,
along with microphone and antenna [A].
Different antennas and microphones
were available on request.
Because the antenna is close to the body, the theoretical range of the
transmitter is reduced, which is why the TX-916 has an output power of 1W.
With fresh alkaline batteries, it can be used continuously for
at least 3 hours. 2
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Body transmitters are also known as a wire, and the person wearing it,
is said to be wired.
In covert operations, body transmitters were often preferred over
body-wearable (tape) recorders,
as they allow other officers to monitor and witness the
operation, while still being able to record the conversation. For
this reason, the TX-916 was commonly used in combination with
the Unitel 225 portable listening post,
which consists of a receiver with a built-in tape recorder.
The device is very similar to the TX-716, which has an output power of 250 mW. 3
It can be used with virtually any
general coverage surveillance receiver,
but was usually supplied in combination with a matching AID
receiver, such as the analogue RX-905,
the digital RX-1000
or the Unitel 225 intelligence kit.
Due to its nature (VHF/FM) it can easily be detected by regualar
TSCM equipment.
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135-150 MHz by special request.
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More when Lithium batteries are used.
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The low-power TX-716 had a battery life of at least 24 hours.
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The image below shows the TX-916 with its case shell removed.
The actual transmitter
measures only 40 × 57 × 18 mm and uses two common
9V battery cells that are connected in parallel.
An antenna — usually a piece of wire — is connected to the mini BNC socket at
the right. The socket at the left is for connection of an electret microphone.
It accepts a screwable 2.5 mm mini-jack.
The device is enabled by setting the slide switch at the centre to the ON
position. For protection against eavesdroppers, the build-in voice scrambler
can be enabled by setting the slide switch at the side to the SC position.
Although this provides basic protection against a casual (unintended)
eavesdropper, it is no match for a professional interceptor as it only
inverts the audio spectrum.
To prevent the batteries from falling out during an operation,
the case shell was usually secured by means of tape. In the same vein, the
power switch was often secured with a piece of tape as well, so that the
transmitter could not be turned OFF accidentally by rubbing against it.
This is why the ID label of the device shown here, is barely readable.
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Device Body-wearable covert transmitter Purpose Evidence gathering Model TX-916 Catalog 95202 Manufacturer Audio Intelligence Devices (AID) Year 1994 (est.) Country USA Users CIA, FBI, Police Band VHF-H Frequency 150-174 MHz Method Crystal 1 Channels 1 Waveform Narrow-band FM Output 1W Antenna Wire (mini-BNC) Power 9V Battery 2 × 9V alkaline (type 1604) Duration 3 hours Microphone Knowles electret with long wire Noice cancelling electret microphone (short wire) Dimensions 93 × 57 × 18 mm Weight 70 g (162 g with batteries)
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The device shown here operates at a spot frequency of 154.935 MHz.
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© Crypto Museum. Created: Friday 19 January 2024. Last changed: Sunday, 29 December 2024 - 09:10 CET.
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