|
|
|
|
|
|
|
Body wires TTI
The device is much smaller than regular
body-wearable transmitters,
such as the CST-581.
It measures just 63 × 28 × 12 mm and weighs no
more than 28 grams, although that does not include the battery.
Instead, it must be connected to an external 9V battery, via a short
cable. This allows the device to be hidden more easily inside a
variety of concealments, like a baseball cap.
The device is crystal-controlled, and the crystal is soldered in place,
which means that it cannot easily be swapped.
Customers had to specify the desired frequency when ordering the device.
|
|
|
|
The CST-702 was introduced around 1997 (est.), as the successor to
the CST-701 from 1992. It is likely that the two devices are identical,
since the CST-702 was not submitted to the FCC for approval.
In that case, the CST-702 is probably the SMD-version of the CST-701.
The device featured here was manufacturerd in or after 2000.
The crystal has a manufacturing date code of 9949, which means
week 49 of 1999. In 2001, the CST-702 was succeeded by the CST-703,
which was synthesizer based — no more crystals — and could be
programmed by the user.
|
-
Year of introduction estimated, based on predecessor (1992) and
successor (2001).
|
The image below shows a typical CST-702 setup with a
highly flexible wire antenna,
and an external electret microphone
with a flexible skin-coloured
cable that terminates in a lockable 2.5 mm jack. The microphone has a thin
steel wire that allows it to be fitted to the clothing. The device is powered
by a standard 9V battery. For extended use, a Lithium variant is recommended.
The device was usually supplied with a tuned semi-rigid wire antenna,
which was made of a piece of teflon coax. When a
flexible antenna was used,
such as in the example above, the antenna has a
small loop at the end,
which allows it to be attached to the clothing by means of a safety pin.
|
A popular concealment for the CST-702 is a baseball cap, such as
the one shown in the image on the right. Sewed inside the cap,
is a pocket
that can hold the transmitter, an external battery and the
wire antenna. In this case, the internal microphone of the CST-702
is used. The wire antenna is
integrated with the baseball cap.
If necessary, a microphone with a short wire can be added to the
setup, and can be hidden behind one of the ventilation holes of
the cap.
|
|
|
The CST-702 is extremely small for the era. It is housed in the same
enclosure as its predecessor, the CST-701. It measures
63 × 27 × 12 mm (including screws and connectors, and weighs just 28 g.
Although we've never seen the CST-701, it seems likely that its circuit is
identical, but that it was (partly) built with conventional parts, whereas
the CST-702 is fully built with SMD parts.
The layout and build quality
of the device are extremely good, as is visible in the image below.
The crystal in the device featured here,
is for 27.750 MHz, which means that it must be multiplied by 6 to get the
output frequency of 166.500 MHz. This done by multiplying the crystal
frequency by 2 and by 3 respectively. Frequency Modulation (FM) is
achieved by modulating the crystal with a varicap diode, whilst
the desired deviation is set with a potentiometer
(microphone volume).
The FCC ID number printed on the device (1P9CST702V) does not exist in the
FCC database, which means that the device has not been submitted for
approval and that it is most likely based on it predecessor — CST-701 — with
only minor modifications, such as replacement for obsolete components,
replacment by SMD parts, and the use of different sockets for antenna or
battery.
|
|
When we received the device in August 2026, we tested it inside
the baseball cap concealment shown above.
It appeared to work as expected. The transmission frequency is as listed
on the device's label (166.500 MHz) and the audio quality is superb.
No restoration or repair of the transmitter was necessary. Although
we were able to use the baseball cap's antenna for the test, the device's
own antenna was missing, so we created one
from a flexible piece of teflon wire.
|
Device Body-wearable surveillance transmitter Purpose Covert overhearing of conversations Model CST-702 Manufacturer TTI Year 1997 (est.) 1 Country USA Predecessor CST-701 (1992) Successor CST-703 (2001) Frequency 150-174 MHz Channels 1 2 Waveform Narrowband FM Oscillator Crystal-controlled Output 200-250 mW Microphone Electret (internal & external) Approval FCC ID: 1P9CST702V 3 Power 9 V/DC Current 50 mA Dimensions HWD: 63 × 28 × 12 mm Weight 28 g Price ?
|
-
Year estimated, based on CST-701 (1992) and CST-703 (2001).
The device featured here, was built in or after 2000,
as its crystal was made in week 49 of 1999.
-
The device featured here works at a spot frequency of 166.500 MHz.
-
This number does not appear in the FCC database. It is likely that
it is based on its predecessor CST-701 (FCC ID: 1P9CST701) of which
there is a record (metadata only).
|
|
|
|
Any links shown in red are currently unavailable.
If you like the information on this website, why not make a donation?
© Crypto Museum. Created: Monday 14 September 2026. Last changed: Monday, 14 September 2026 - 21:23 CET.
|
 |
|
|
|
