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TAR-224A
CIA spy radio set

TAR-224 was a highly compact self-contained spy radio set, developed around 1970 by AVCO Corporation in Cincinnati (Ohio, USA) for the US Central Intelligence Agency (CIA), as a successor to the ageing GRC-109 (RS-1) of the 1950s. It was intended for communication with field agents behind enemy lines. Due to mechanical and electrical problems, nearly all units were reworked by WES Industries in 1972 [6]. After a long operational life, it was phased out in the late 1980s.

The entire unit is completely waterproof, with all switches and controls at the front panel properly sealed, allowing the radio to be stored under harsh conditions for an extended period of time. A plastic lid can be placed over the controls to protect them against dust and dirt. It is held in place by three metal latches at the edges.

The image on the right shows a typical TAR-224A unit, without the optional CS-224 30-channel crystal selector installed. The unit roughly consists of two parts: the receiver (RX) at the left, and the transmitter (TX) at the right.
  
TAR-224a spy radio set (USA)

The radio coverages all frequencies between 2 and 24MHz. The receiver has a Variable Frequency Oscillator (VFO), allowing continuous tuning of all 4 frequency bands, whereas the transmitter is crystal operated. The unit can be powered by an external 12V source that is connected to a 3-pin socket at the front left, or by a special 12V battery pack that is installed behind a watertight panel at the front left. A plastic grip, at the left of the radio, allows the unit to be carried around easily.

The TAR-224 was introduced in 1970 and the user manual was updated once in September 1971. The unit shown here, was probably issued in the early 1970s, and was last inspected in 1976. Most TAR-224 units were used by the CIA on special (overseas) missions [4], but the radios were also used by intelligence services in Europe [1]. It is known to be used on a mission in Angola in 1975. According to CIA communication specialist Teddy Roberts, the TAR-224 was still being used in operational context in 1983, when he trained a unit of US Army Green Barets on its use.

TAR-224A with top lid in place
TAR-224a spy radio set (USA)
TAR-224a spy radio set (USA)
TAR-224A front panel
Phone/Key sockets and Power socket
Adjusting the RX frequency
TAR-224A in upright position
Carrying the TAR-224A
A
×
A
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TAR-224A with top lid in place
A
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TAR-224a spy radio set (USA)
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TAR-224a spy radio set (USA)
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TAR-224A front panel
A
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Phone/Key sockets and Power socket
A
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Adjusting the RX frequency
A
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TAR-224A in upright position
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Carrying the TAR-224A

Controls
The image below gives a good view of the TAR-224 controls and connections. The left half of the radio contains the receiver (RX), whilst the right half contains the transmitter (TX). The two sections are separated by a vertical white line at the center. The radio can be powered by an internal 12V battery, but also by an external power source that is connected at the bottom left.

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The receiver has a Variable Frequency Oscillator (VFO) that can be adjusted to any frequency between 2 and 24MHz, but the transmitter requires a suitable crystal for each TX frequency. The crystal is inserted into a special socket at the bottom of the TX section. At the top right is room for an expansion unit, such as the CS-224 crystal selector or a digital frequency synthesizer.


Parts
TAR-224 transceiver
TRX
Rechargeable NiCd battery pack
Battery charger
Power supply unit
PSU
KE/M-8 burst keyer
Burst encoder
Tape cartridge voor coder/keyer
Military handset
Military headset
Battery cable
DC
Quartz crystals
Crystal selector
Frequency synthesizer
Long-wire antenna
Transceiver   TAR-224
The image on the right shows the actual TAR-224 transceiver, which is fully self-contained. It is powered by an internal battery and requires the installation of a quartz crystal, an external (wire) antenna, and a handset.

The unit can be covered with a plastic lid that is held in place by three spring-clips at the edges. When all options are correctly fitted, the unit is water-tight, allowing it to be stowed under harsh and moisterous conditions.
  
TAR-224a spy radio set (USA)

Battery pack   BA-224
The TAR-224 was usually powered by an internal rechargeable NiCd battery pack that provided the necessary 12V DC power supply. It consists of 10 cells of 1.2V each, and can be charged in-situ by means of the EMBC-224 battery charger.   
BA-224 battery pack

Battery charger   EMBC-224
The NiCd battery pack can be charged in-situ by means of the EMBC-224 battery charger shown in the image on the right. It should be connected to the AC mains, by means of the external mains power cord that is also shown.

The charger has a hinged lid below which a fixed 3-pin power cable is stowed. This cable should be connected to the power socket at the front panel of the TAR-224.
  
EMBC-224 battery charger

Power supply unit
The TAR-224 can also be powered by an external 12V DC source, such as the battery of a car, or by the purpose-built Power Supply Unit (PSU) shown in the image on the right.

The PSU should be connected to the 3-pin power socket at the front panel of the TAR-224. As soon as an external 12V DC voltage is supplied, the internal battery is disconnected.
  
W12-6 PSU with cables

Burst keyer   KE/M-8
In order to reduce the chance of interception and discovery by means of radio direction finding (RDF), a high-speed burst transmitter, or keyer, can be used. It allows pre-recorded (preferably encrypted) messages to be sent at speeds up to 300 wpm, and reduces the on-air time.

The image on the right shows the KE/M-8 keyer that was supplied with the TAR-224. It is the motor-driven version of the KE-8, which uses a spring-loaded wind-up mechanism.

 More about the CK-8 coder/keyer

  
Burst keyer KE/M-8

Burst coder   CO/B-8
Messages were pre-recorded on a tape cartridge that was installed on the CO/B-8 encoder shown in the image on the right. The coder has a large disc at the top, which allows any of the 26 letters of the Latin alphabet to be selected. By operating the lever, the selected letter is recorded onto the tape in morse code.

The coder does not require an external power source. Instead, the energy that is required for its operation, is generated by a miniature power generator that is operated by the lever.

 More about the CK-8 coder/keyer

  
Burst coder

Tape cartridge   CA/A-3B
The image on the right shows a typical tape cartridge, of which several were supplied with the radio set. The cartridge can be installed on the coder in order to record a (preferably encrypted) message in morse code.

Once the message is complete, the cartridge is removed and installed on the keyer, which in turn is connected to the TAR-224. When the start button at the rear of the keyer is pressed, the message will be sent at 300 wpm.

 More about the CK-8 coder/keyer

  
CA/A-3B tape cartridge

Handset
When using the TAR-224 for speech (phone), a microphone/speaker combination – such as the handset shown in the image on the right – should be connected to the 6-pin U-229 socket marked PHONE at the front panel.

The handset has a so-called push-to-talk (PTT) switch at the side. Pressing the switch enables the transmitter. Releasing it enables the receiver.
  
Handset

Headset
When using the TAR-224 only for messages in morse code – for example in combination with the burst keyer – it is recommended to use a headset instead of the handset shown above, as a microphone is no longer required.

The image on the right shows a typical headset that was commonly supplied with a TAR-224.
  
Headset

Battery cable
When using the TAR-224 in the field, the mains power network might not be available. In such cases it is possible to power the transceiver from an external 12V DC power source, such as the battery of a car, using the cable shown in the image on the right.

The cable has two large crocodile clips at one end, for connection to the battery terminals. The other end has a military 3-pin plug that should be connected to the power socket at the front panel of the TAR-224.

  
Battery cable

Crystals
The transmitter is crystal operated and requires a quarz crystal with an CR-18/U (HC-6/U) shape to be installed in the crystal socket at the centre of the bottom edge of the front panel.

The number of readily available channels can be expanded by installing a crystal selector or a frequency synthesizer in the slot in the upper right corner of the front panel.

 More about crystal shapes
  
Suitable crystals for TAR-224

Crystal selector   wanted
The TAR-224 has a slot in the upper right corner, in which a crystal selector can be fitted. It gives the transceiver the ability to quickly switch between 30 pre-installed channels.

No image available at present
  

Synthesizer
The slot in the upper right corner of the front panel — normally used for an optional crystal selector — also accepts a digital frequency synthesizer, which allows the desired frequency to be selected by means of thumb-wheels.

Apparently, a small series of synthesizers was professionally manufactured, and was housed in the modified enclosure of a crystal selector.
  

Antenna
The TAR-224 requires a single wire antenna to be connected to the ANTENNA terminal at the right edge of the front panel. When tuning, the internal motor-driven antenna matcher, will try to match the antenna. If it fails to do so, a different antenna length should be tried.

Furthermore, it is important to connect a proper ground (counterpoise) to the GRD terminal (just below the ANTENNA terminal).
  

BA-224 battery pack
BA-224 battery pack
Model number, serial number and power terminals
BA-224 battery outside the battery compartment of the TAR-224
BA-224 battery installed in the TAR-224
EMBC-224 battery charger
EMBC-224 battery charger
Power cable stowed below hinged lid
Close-up of power plug
Mains power cord connected
Burst keyer KE/M-8
KE/M-8 keyer seen from the rear
Controls
Suitable crystals for TAR-224
B
×
B
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BA-224 battery pack
B
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BA-224 battery pack
B
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Model number, serial number and power terminals
B
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BA-224 battery outside the battery compartment of the TAR-224
B
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BA-224 battery installed in the TAR-224
B
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EMBC-224 battery charger
B
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EMBC-224 battery charger
B
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Power cable stowed below hinged lid
B
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Close-up of power plug
B
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Mains power cord connected
B
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Burst keyer KE/M-8
B
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KE/M-8 keyer seen from the rear
B
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Controls
B
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Suitable crystals for TAR-224

Components
Receiver   RR-224
The left half of the TAR-224 is taken by the receiver (RX). It consists of a colour-coded 4-position BAND selector and a 4-row frequency scale. The frequency can be adjusted with the knurled knob just below the frequency scale. The knob has a foldable spring-loaded handle for faster tuning.

At the bottom of the front panel are the MODE-selector, the Beat Frequency Oscillator (BFO), AF gain (volume) and RF gain (HF pre-amplifier). When the RF adjustment is set to the leftmost position, the Automatic Gain Control (AGC) is enabled. The receiver also contains the POWER switch and the connectors for external power, microphone, speaker and external morse key.

The frequency scale can be calibrated by setting the MODE-selector to CAL. This enables the built-in reference oscillator, which produces a carrier at 500kHz intervals (3MHz, 3.5MHz, etc.).
  
Adjusting the RX frequency

Once the reference oscillator is selected, tune the receiver to a carrier near a rounded frequency (e.g. 3MHz) and adjust the scale ruler (CAL ADJ) so that its center positions lines up with the frequency. The receiver is suitable for the reception of morse signals (CW) and voice (AM), but can also receive Single Side Band signals (SSB) by the using the built-in Beat Frequency Oscillator (BFO). For normal operation (CW) the BFO should be set to the center position (0). For SSB signals, the BFO knob can be tuned (-) for Lower Side Band (LSB) and (+) for Upper Side Band (USB).

Adjusting the RX frequency
Band selector
The four frequency ranges (yellow selected)
Adjusting the BFO (SSB)
Phone/Key sockets and Power socket
Power/MODE switch (OFF, RX, TX)
Connecting antenna and counterpoise
Calibrating the scale
C
×
C
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Adjusting the RX frequency
C
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Band selector
C
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The four frequency ranges (yellow selected)
C
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Adjusting the BFO (SSB)
C
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Phone/Key sockets and Power socket
C
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Power/MODE switch (OFF, RX, TX)
C
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Connecting antenna and counterpoise
C
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Calibrating the scale

Transmitter   RT-224
The transmitter is crystal-operated and is suitable for CW (morse) and AM (voice) communication. A suitable CR-18/U crystal can be inserted in a special socket at the front center. If rapid channel selection is needed, an optional crystal selector can be installed in a special slot at the top right. If the selector is not installed, the slot is closed by a thick plexiglass panel. It is also possible to install a digital frequency synthesizer — controlled by five thumb-switches — in this position.

When using the (optional) channel selector, three banks of 10 channels each are available. When a single crystal is inserted into the crystal socket at the front panel, the 30-channel selector is disabled. Two frequency ranges are available via a selector: 2-12MHz and 12-24MHz. In the 12-24MHz mode, the crystal frequency is doubled.

When sending messages in morse code, the TAR-224 was normally used in combination with a burst-keyer, in order to avoid detection and interception by a potential eavesdropper. The standard burst encoder was the CK-8 (GRA-71).
  
Using the built-in morse key

Alternatively, a morse key could be connected to one of the 6-pin U-229 connectors at the front left, allowing manual transmission of morse signals. In case of an emergency, the built-in morse key could be used for this as well. The minimum output power for an unmodified TAR-224 is specified at 13W in CW and 4W in AM, but in practice the output power was much higher.

The radio shown here delivers 21W in CW and up to 8W in AM [3]. When used for phone (voice), a handset or headset could be connected to one of the 6-pin U-229 sockets at the front left. The (wire) antenna and a suitable counterpoise should be connected to the two snap-on terminals at the right edge of the transmitter.

The TAR-224 has a built-in Antenna Matcher that allows the transmitter to be adjusted for the (wire) antenna in use. This can be done by holding down the morse key whilst manually rotating the antenna tuning knob at the right.
  
Starting the auto-tuner (pull knob)

Alternatively, the Automatic Antenna Tuner (AAT) can be enabled by pulling-out the antenna matcher knob. This engages a novel electronically controlled motor-driven coil mechanism that will try to obtain the highest power output at the best possible Standing Wave Ratio (SWR).

TAR-224 with standard NATO-issue handset
Using the built-in morse key
Selecting the TX range
Tuning indicator and battery check
Crystal socket with built-in switch
Placing a crystal in the socket on the front panel
Starting the auto-tuner (pull knob)
Connecting antenna and counterpoise
D
×
D
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TAR-224 with standard NATO-issue handset
D
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Using the built-in morse key
D
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Selecting the TX range
D
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Tuning indicator and battery check
D
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Crystal socket with built-in switch
D
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Placing a crystal in the socket on the front panel
D
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Starting the auto-tuner (pull knob)
D
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Connecting antenna and counterpoise

Power
The TAR-224 should be powered by any 12V DC source that can deliver 5.9 A. The operational voltage range is 10.8 to 13.2 V DC. When using the external power supply unit, the so-called battery-protection circuit automatically disables the internal battery in order to prevent damage.

When a suitable power supply/battery charger is used, it can be used to charge the battery simultaneously. For this purpose, a separate contact is used in the connector and the battery.

The battery itself is a single-unit rechargable 12V accumulator that is installed behind a water-tight door at the front left of the radio. In the battery compartment are three contact pins, marked J1, J2 and J3. The first pin (marked J1) is connected to the +12V whilst J3 is connected to the negative terminal (-) of the battery. The center pin (J2) is for charging the battery in-situ.
  
Selecting the internal battery

Please note that the battery-protection circuit uses a latching (bistable) relay. Once the internal battery is switched off, it will remain disabled (even when the external power source is removed) until the RESET POWER buttonon the front panel – to the left of the MODE selector – is pressed.

Please note that when putting the radio in storage, the power selector at the front panel should be set to the OFF position (left). When closing the radio, an index stub on the inside of the plastic top cover, prevents it from being fitted when the power switch is not in the correct position (OFF). The top cover is locked in place by means of three latches at its sides. When placed in the upright position, the radio can be carried around by means of the plastic grip at on of the short sides.

TAR-224 with opened door to the battery compartment
BA-224 battery installed in the TAR-224
Contacts inside the battery compartment
External connections
Selecting the internal battery
Power/MODE switch (OFF, RX, TX)
TAR-224A with protective cover (top lid)
Index slot to ensure the radio is OFF when the lid is closed
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TAR-224 with opened door to the battery compartment
E
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BA-224 battery installed in the TAR-224
E
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Contacts inside the battery compartment
E
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External connections
E
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Selecting the internal battery
E
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Power/MODE switch (OFF, RX, TX)
E
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TAR-224A with protective cover (top lid)
E
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Index slot to ensure the radio is OFF when the lid is closed

Interior
The TAR-224 is a compact self-contained transceiver. The complete radio is housed in a die-cast aluminium case that measures approx. 12 x 18.5 x 31 cm and weights just 6 kg. The case is fully waterproof, and all controls, connectors and adjustments have watertight rubber gaskets.

After loosening 10 torx bolts at the edges of the front panel, the entire radio can be lifted out of the case. The image on the right shows the interior of the radio with the front panel facing down. At the left is the transmitter with the coils of the Automatic Antenna Tuner clearly visible (the preotective cover is removed here). At the right is the receiver and (at the front) the internal wiring of the various controls at the front panel.

The construction of the receiver is extremely complex. It is attached to the front panel with just four bolts and can easily be removed.
  
TAR-224A interior

The receiver is connected to the rest of the radio with only one 29-pin connector. After removing the knobs and the four bolts from the front panel, the entire receiver can be lifted from the connector and, hence, the interior. The RX block consists of a series of shielded units that are bolted together. They are wired together via two (green) 14-pin connectors at the side.

The image on the right shows the RX unit with the frequency scale facing upwards. The 29-pin connector and the two 14-pins connectors are visible at the left. A separate SMC connector is used for the RF antenna input (at the front).

In order to accomodate the four frequency ranges, a complex construction is used for the Antenna Matching unit, the RF pre-amplifier and the Local Oscillator (LO). These three units are mounted side-by-side in a single enclosure, with a common axle (attached to the BAND selector) running through each compartment.
  
RX unit with its connectors at the left

As each of the three units has to be adjusted differently for each frequency band, four different tuning sections are mounted around the common axle in each compartment. When rotating the BAND-selector at the front panel, the axle turns 90° with each step, selecting a different section.

The image on the right shows the interior of the three units. The tuning section are clearly visible at the center of each compartment. The rotation from the BAND-selector is carried over to the common axle by means of a serial of cogwheels and a chain belt at the side of the receiver.

The tuning section is normally closed by a common metal plate that covers the three sections (the cover is not shown here). The signals from the HF pre-amplifier and the Local Oscillator (LO) are fed to the IF-stage that is mounted to the bottom of the receiver unit.
  
RX interior. From left to right: Antenna matching, RF Amplifier and Local Oscillator (LO).

The right half of the TAR-224 contains the transmitter (TX), of which the Automatic Antenna Tuner (ATT) is arguably the most interesting unit. It is mounted in the front right corner of the radio. It consists of a large adjustable capacitor and a very special variable tuning coil.

The image on the right shows the ATT after its protective cover has been removed. At the left is the tuning coil. It is connected via a cog wheel mechanism at the bottom, to a synchronized rigged solid metal spool behind it.

At the front right is the electro-motor. It drives the tuning mechanism at 1000 RPM. Also connected to the mechanism is the large tuning capacitor that is just visible behind the motor. When enaging the ATT (by pulling the knob at the front panel), the tuning capacitor and the coil are adjusted for optimum SWR.
  
Clear view of the double winding/unwinding coil

A novel winding/unwinding mechanism is used for the adjustment of the coil. When running, the wiring is moved from the coil to the solid spool and vice versa. As a result the induction of the coil is increased or decreased. When starting the ATT, the mechanism is first fully wound back to the reference position. It then runs forward and will stop when the desired position is reached.

Radio removed from the case
TAR-224A interior
TAR-224A interior (top view)
Antenna Tuner (left) and receiver (right)
TAR-224A interior
TAR-224A interior (side view)
TAR-224A interior
RX unit with its connectors at the left
Band selector mechanism
Receiver internal connector
RX interior. From left to right: Antenna matching, RF Amplifier and Local Oscillator (LO).
Receiver with IF-stage removed
IF-stage
TAR-224A interior. The cover of the automatic anenna tuner has been removed.
Automatic Antenna Tuner
Clear view of the double winding/unwinding coil
F
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F
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Radio removed from the case
F
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TAR-224A interior
F
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TAR-224A interior (top view)
F
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Antenna Tuner (left) and receiver (right)
F
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TAR-224A interior
F
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TAR-224A interior (side view)
F
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TAR-224A interior
F
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RX unit with its connectors at the left
F
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Band selector mechanism
F
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Receiver internal connector
F
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RX interior. From left to right: Antenna matching, RF Amplifier and Local Oscillator (LO).
F
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Receiver with IF-stage removed
F
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IF-stage
F
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TAR-224A interior. The cover of the automatic anenna tuner has been removed.
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Automatic Antenna Tuner
F
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Clear view of the double winding/unwinding coil

Aftermarket modifications
The original TAR-224 radios, as supplied by AVCO in 1970, had serious mechanical and electrical problems. There were many contact problems with the through-plated holes of the printed circuit boards (PCBs), badly soldered ground planes and incorrectly stripped teflon wiring, which led to premature failure of many units. Flaws in the mechanical design caused inconsistent behaviour of certain controls, friction in the fragile tuning mechanism and unnecessary wear of some parts [6].

By the time AVCO was ready to ship the units to the CIA, the company had virtually run out of resources and failed to perform a proper final test. In fact, quality control (QC) at AVCO had been so bad, that many units were dead on arrival (DOA). In addition, the units that did work, often exhibited electrical and mechanical faillures early in their live when they were used in the field [6].

The high faillure rate of the TAR-224 led the CIA to look for a company that could repair, modify and improve the design, less than a year after its introduction. The contract for this rework was awarded to WES Industries in Dumfries (VA, USA), where all radios were modified during the course of 1972. The rework required full disassembly of the radio and consisted of modifications in the electronic circuits, repair of contact problems, repair of badly stripped wiring, conformal coating of the PCBs and many mechanical modifications.

The image on the right shows a part of the hand-made drawing that were made by WES engineers.
  
Snippet from the hand-made disassembly and modification drawings [D]

A full rundown of all modifications carried out at WES Industries in 1972 is available for download below. Also available are the hand-made drawings of the mechanical modifications, a description of the test setup and the final test sheet that was supplied with each unit once the modifications had been completed and the radio had sustained a full burn-in test. Many thanks to Norris Dale — he was part of the team that did the rework — for sharing this part of the TAR-224 history [6].

 Modification and Test Proposal
 Modifications and assembly notes
 Quality Control and Final Test Sheet
 Standard Test Setup for TAR-224


Connections
The diagram below shows the pin numbering and connections of the connectors at the front left of the TAR-224. The two U-229 sockets (left) are identical [5]. They both are fully wired (A-F) in parallel. The other socket (right) is the socket for the external power source. A suitable connector for the latter is the Amphenol PT06A-8-3S, which is available from distributors like Digi-Key (US).


 PHONE/KEY
Pin Function Description
A GND Ground (common wire)
B SPK Speaker (separate, or part of handset/headset)
C PTT Push-to-Talk switch (connects to ground)
D MIC Microphone (separate or as part of handset)
E KEY External (morse) key
F +12V Power supply (output) for external burst encoder
 POWER
Pin Function Description
A +12V Power supply (input)
B GND Ground (common wire)
C CHG Charge input (for internal battery)
 BATTERY
Pin Function Description
J1 +12V Power supply (input)
J2 CHG Charge input (for internal battery)
J3 GND Ground (common wire)

TAR-224 and the CIA
Terry Roberts worked for the CIA for 40 years 1

Teddy Roberts started his professional life back in 1960 when, fresh out of high school, he attended a Radio Intercept Operator's Training in Imperial Beach (California, USA). After passing a Naval communications training later that year, he got his first assignment at the US Naval Communications Facility in Adak (Alaska), where he learned to work with sophisticated high-powered computers, video display terminals and the collection and analysis of communications signals. In 1963 he was transferred to the Naval Communications Station in Honolulu (Hawaii).

In 1964, following his release from the US Navy, Terry entered communications training with the CIA, after which he was assigned to the American Embassy in East Africa. Later that year, whilst being on medical hold for any overseas posting, Terry was temporarily assigned with an engineering office at the CIA's communications training facility.

After his medical hold had been cancelled in 1965, he was assigned to a US Embassy in West Africa. In the following years, he worked in several countries including Germany, Libya, Israel, the Phillipines, and China, until he landed in London (UK) for a five-year assignment with the US Embassy. During these years he worked closely with the British Intelligence services in support of NATO war planning programs.

In 1988, he was assigned to CIA Headquarters in Virgina, where he worked as chief of recruitment for the CIA's Office of Communications. A few years later he was assigned as Deputy Chief of Operations of the Communications Area Operations staff for Africa. In 1992, Terry was assigned as associate director of the CIA's Global Network Management Center, planning the CIA's world-wide communication needs on a daily basis, until he retired from the CIA in 1995.

The image on the right shows Terry Roberts holding a TAR-224A in his hands. He used this radio in an operational context in 1983, when training a unit of Army Green Berets on its use.
  
Photograph by Elaine Blaisdell. Copyright 2009, The Journal [4]. Reproduced here with kind permission.

One of his most memorable experiences was his involvement in the arrest of Daulton Lee and his partner in crime Crystopher Boyce, during a three-year tour in Mexico, where he worked in close cooperation with the FBI. Whilst working for US defense contractor TRW, Boyce used a Minox-B spy camera to copy classified government information, which Lee sold to the Soviets. Lee and Boyce were eventually arrested in 1977, and were sentenced to life and 40 years respectively. The story was later told in the 1979 book (and later in the 1985 movie) The Falcon and the Snowman.

  1. Thanks to The Journal for allowing us to reproduce part of their 2009 publication [4] and the photograph above. The photograph was made by Elaine Blaisdell, who also wrote the original article.

Known serial numbers
  • 001
    PA3ECT (Netherlands)
  • 106
    Private collector
  • 193
    eBay
  • 232
    eBay
  • 306
    Private collector
  • 315
    eBay
  • 328
    eBay
  • 359
    eBay
  • 382
    Museum Gausdal
  • 398
    eBay
  • 410
    Private collector
  • 434
    Crypto Museum
  • 437
    eBay (France)
  • 444
    Pete McCollum
  • 472
    Receiver is chassis #444
  • 484
    Transmitter in chassis #444
  • 521
    Crypto Museum
  • 549
    Private collector (NL)
  • 553
    eBay
  • 576
    Private collector (Italy)
  • 583
    eBay
  • 600
    Private collector (NL) TX only
Help required
Little is known about the operational use of the TAR-224, so we'd like to hear from people who actually worked with it in the field. Furthermore, we are looking for the optional CS-224 Channel Selector that can be installed in the empty slot in the top right corner of the radio.


Specifications
  • Manufacturer
    AVCO Corporation, Ohio (USA)
  • Introduction
    1970
  • Power
    12V DC
  • Current
    50 mA (RX), 4.3 A (TX)
  • Dimensions
    311 x 184 x 121 mm
  • Weight
    6 kg
Receiver
  • Type
    Superheterodyne
  • Frequency
    2 - 24 MHz
  • Bands
    4 (2-3.7 MHz, 3.7-6.9 MHz, 6.9-12.9 MHz, 12.9-24 MHz)
  • Calibrator
    500 kHz ± 0.01%
  • Modulation
    AM, CW, SSB
  • IF
    455 kHz
  • BFO
    ± 3 kHz
  • Output
    ≤ 2 mW into 500Ω
Transmitter
  • Frequency
    2 - 24 MHz
  • Bands
    2 (1-12 MHz and 12-24 MHz)
  • Modulation
    AM (phone), CW (morse)
  • Output
    20 W
  • Antenna
    Single wire, 40 - 250 Ω
  • Speed
    ≤ 300 wpm (with external keyer)
  • Crystal
    CR-18/U (HC-6/U), parallel resonance, 32 pF 1
  1. Fundamental frequency in 2 - 12 MHz range, doubled in 12 - 24 MHz range.

Options
Documentation
  1. Instruction Manual for Radio Set TAR-224
    AVCO Corporation, 15 September 1971.

  2. TAR-224 Inspection Work Sheet for serial number 549
    16 September 1976. 2 pages.

  3. TAR-224 Modification and Test Proposal
    WES Industries, Inc. March 1972. 1

  4. TAR-224 Modifications and assembly notes
    WES Industries, Inc. April 1972. 1

  5. TAR-224 QC and Final Test Sheet
    WES Industries, Inc. April 1972. 1

  6. TAR-224 Standard Test Setup for TAR-224
    WES Industries, Inc. January 1972. 1
  1. Document kindly supplied by Norris Dale [6].

References
  1. Louis Meulstee, TAR-224
    Wireless for the Warrier. Volume 4. September 2004. ISBN 0952063-36-0.

  2. AVCO Corporation, Instruction Manual for Radio Set TAR-224
    80045 PRC 31/570. 15 September 1971.

  3. TAR-224 Inspection Works Sheet
    TAR-224 Serial Number 549. 16 September 1976.

  4. Elaine Blaisdell, In service to his country
    Teddy Roberts spent 40 years working for the CIA around the world.
    The Journal (Website). 28 February 2009. Retrieved November 2012.

  5. Crypto Museum, U-229 connector description
    Crypto Museum website. December 2011.

  6. Norris Dale, TAR-224 1972 Modification History
    Personal correspondence, August 2018.
Further information
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Crypto Museum. Created: Wednesday 21 November 2012. Last changed: Thursday, 12 November 2020 - 11:06 CET.
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