Clandestine spy radio transmitter
TI-466 AB, or SIRIUS AB, or just AB,
was a spy radio
transmitter, developed in Czechoslovakia
between 1958 and 1962 by Správa 6 1 for the
secret state police (StB)
and Správa 1 (espionage)
for use in clandestine operations in the
West European theatre. The transmitter is part of
the SIRIUS radio station, has a frequency range of 4-16 MHz
and delivers approximately 80W.
The image on the right shows a typical AB,
which measures 27.5 x 15.5 x 6.5 cm and weights: 4.2 kg.
Contrary to the other items of the SIRIUS radio station, which are all
painted grey hammerite, the case of the AB is black.
The transmitter has a built-in mains transformer (PSU) that is suitable
for the most regular mains voltages around the world. The PSU also powers the
matching PLUTO receiver,
which should be connected to the DIN
socket at the left side. At the front is a 6-pin socket for connection of
TI-485 (DÁVAČ) burst encoder.
Unlike most other spy radio transmitters of the same era, nearly all of
which are crystal-operated, the TI-466 AB transmitter is free-running,
allowing it to be used on any frequency in the 4-16 MHz range. In order
to avoid any inaccuracies, the device has a built-in crystal calibrator.
Development of the AB started in 1958, a few years after the
introduction of the PLUTO spy radio set, and took several years before
the first sets were delivered in 1962. During its lifetime, it
was modified and simplified several times. Once the sets were decommissioned
in the early 1980s, all but one were destroyed. It is likely that the one
featured here is the only surviving example. The SIRIUS transmitter was
succeeded in 1966 by the SIRIUS III
transmitter (TI-526) with separate PSU.
Správa 6 refers to Government Department 6: Communication Technology.
The image below shows the various controls and connections of the TI-466 AB.
Operating the device is pretty straightforward and requires only limited
knowledge of its operation. Before connecting it to the mains, the
at the top left should be check for the proper AC main voltage.
The PLUTO receiver
should be connected to the 6-pin DIN socket at the left,
and the DAVAC burst encoder
to the rectangular 6-pin socket at the front
right of the transmitter.
The transmitter has two frequency ranges: (1) 4-8 MHz and (2) 8-16 MHz,
and is freely tuned to any frequency within these two ranges. A built-in
calibrator with an external crystal and an earpiece can be used to check
the frequency scale. The crystal should be in the 120kHz range.
The image below shows the block diagram of the AB
[B]. The main oscillator is free-running and is visible at the center.
It produces the base frequency (f0) in the range 2-4 MHz,
which is then doubled to 4-8 MHz (range 1) and (optionally) doubled
once more to obtain 8-16 MHz (range 2).
The transmitter is designed for operation in combination with an external
high-speed morse recorder, also known as a burst encoder, which is shown
at the top left. The signal from the burst encoder is first re-shaped and
amplified, and then used to enable/disable the transmitter.
The TI-466AB has two sockets for the connection of peripheral equipment:
a 6-pin 270° female DIN socket for connection of the receiver, and a 6-pin
rectangular female socket for connection of the burst encoder. Below is the
pin-out when looking into the sockets from outside the case.
- 170V AC (HT)
- 0V AC
- 6.3V AC (LT)
- Modulation (+)
- LT (6.3V AC)
- LT (6.3V AC)
- HT in
- HT out
- Modulation (GND)
Frequency4-16 MHz (two ranges: 4-8 MHz and 8-16 MHz)
ModulationF1 (FSK), later modified to A1 (CW)
Deviation2kHz ±160 Hz
Stability10-6 / °C
Acuracy±160 Hz @ +10°C to +30°C
- ±640 Hz @ -10°C to +25°C
- ±1240 Hz @ -20 to +60°C
Drift±20 Hz per 20 seconds after 10 minutes warming up
Muting30dB (during calibration)
Mains110/120/210/220 V AC (50-60 Hz)
Session15 seconds (25 seconds max)
IntervalMinimal 1 minute between two sessions
Calibration2 minutes (max)
Temperature80°C (max) protected
Earpiece50 Ohm (calibrator output)
PA28W (without pre-heat)
- Anonymous, SIRIUS spy radio set - THANKS!
Devices kindly donated by anonymous former user. July 2015.
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© Crypto Museum. Last changed: Thursday, 20 August 2015 - 22:14 CET.