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MA-4778
Cougar DS-102 key fill interface

The MA-4778 is an electronic key transfer device, also known as a key filler or fill gun, developed by Racal in Reading (UK), especially for voice encryption devices and secure radios that were fitted with a special encryption module that uses the highly secret UK/US SAVILLE encryption algorithm.

Typical xamples of such devices are the Racal MA-4777 voice encryption unit and the Racal PRM-4515 Cougar secure handheld radio. Such devices are generally issued with a standard Racal MA-4437 crypto unit, and the keys are loaded by means of the Racal proprietary MA-4073 programmer or an MA-4083 fill gun.

In some cases, the secure devices were issued with a special crypto module that implemented the highly secret GCHQ/NSA-developed SAVILLE algorithm. Such modules were generally only released to the US/UK government and NATO.
  
Racal MA-4778 key loader with DS-102 protocol

As this special crypto module uses the DS-102 protocol for loading the keys, the standard Racal key loaders can not be used. At the same time, standard DS-102 key loaders, such as the American KYK-13, are not compatible with the Racal proprietary interface, which is where the MA-4778 comes in. It is shown in the image above and has a fixed cable with a 7-pin Clansman-wired 105 plug at the end, for connection to the secure radio or external voice encryption unit.

At the bottom is a standard American-style U-299 socket for connection of a standard DS-102 compatible key filler. This allows SAVILLE keys to be distributed in the usual manner, using existing key fillers such as the KYK-13 and the KOI-18. By using such a device to fill the MA-4778, the same key may then be transferred to Racal devices with a compatible crypto module.

The device has only one control: the recessed INITIATE button at the front panel. Furthermore, it has two key compartments, each of which is indicated with a red LED (FILL 1 and FILL 2).
  
Using a KYK-13 to load a SAVILLE key into the MA-4515 Cougar

After connecting a pre-loaded DS-102 filler to the U-229 socket of the MA-4778 and connecting the MA-4778 to the radio or encryption device to be loaded, the INITIATE button on the MA-4778 should be pressed in order to start a key transfer. The KYK-13 is shown as an example in the image above. Note that, when using a KYK-13, the two keys must be transferred in two separate actions. Prior to this, the required key compartment (1-6) on the KYK-13 should be selected.

Racal MA-4778 key loader with DS-102 protocol MA-4778 ready for operation KYK-13 connected to the MA-4778 Using a KYK-13 to load a SAVILLE key into the MA-4515 Cougar Initiating a key transfer Using a Philips UP-2001 key filler Both connections Key compartment indicators
Interior
The MA-4778 is housed in a common 'off the shelf' die-cast aluminium enclosure. This indicates that it was probably not manufactured in large quantities. The device can be opened by removing the 4 large bolts in the corners of the front panel. The entire front panel may then be removed.

Inside the MA-4778 are three PCBs. One is mounted at the rear of the front panel and holds the 3 LEDs that are visible at the front (1, FILL 1 and FILL 2). The two other PCBs are mounted inside the case itself. The upper PCB holds the 9V battery and a small auto ON/OFF circuit.

The actual filler interface itself is on the PCB that is mounted at the bottom. It contains a rather simple circuit consisting of a microcontroller with built-in RAM and EPROM, and two serial ports that are used for connection to the radio's audio socket and one for the DS-102 key filler.
  
MA-4778 interior

The unit is powered by an internal 9V battery and is switched ON automatically when it is connected to the radio (even when the radio is not switched on). After disconnecting, the unit turns itself OFF after approx. 10 seconds. The INITIATE button on the MA-4778 is used to start a key transfer from the KYK-13. Please note that it is only possible to load SAVILLE keys into a radio or voice encryption device that has the appropriate SAVILLE-compatible module fitted.

MA-4778 interior MA-4778 interior MA-4778 interior Battery installed Disassembled MA-4778 Battery holder and auto ON/OFF circuit Close-up of the auto ON/OFF circuit The actual interface/controller
Connections
The 7-pin plug at the end of the fixed cable is wired for Clansman-style sockets on compatible secure radios, such as the Cougar PRM-4515. The wiring of the plug is as follows:

  1. Program input
  2. Wideband programming
  3. Power out
  4. Ground
  5. Key fill data
  6. CTS output
The U-229 socket at the bottom (U-283/U) is wired as follows:

  1. Gound
  2. Ack
  3. Data
  4. Clock
Further information
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Crypto Museum. Last changed: Wednesday, 20 May 2015 - 20:31 CET.
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