BRUIN
BRUIN was a British trunk communications system that extended telephone and data services to major headquarters units down to brigade level. It used UHF and SHF Line of sight radios (C70 as well as C 50), interconnected through Commcentres. The heart of the voice system were Strowger terminal and tandem telephone exchanges.
The “Fish Frier” is a term used to refer to the log periodic antenna that the C50 used, which looked somewhat like a fish frier used in barbecues. There were two antennas mounted on the same mast, polarized at 90 degrees to each other, one for transmit and one for receive. The C70 (Siemens) used twin helical antennas at SHF. There may be some dispute as to whether the C70 was, technically, SHF, but it was classed as SHF.
A technician who worked on the BRUIN system has provided this recollection. "I worked on the set up of Bruin briefly before moving back to EW. There were two types of radios used. The first was the Plessey C50/R236 combination. It operated in the frequency range 225-400 MHz for TDM and FDM operation. RF output is either 10,50, or 250 watts. The station superseded Station Radio C41/R222. The C50 transmitter, as I recall, had its own separate power supply as did the receiver. A tuning turret and synthesizer were fitted and the six transmit crystals in the tuning turret were all we needed to tune up the transmitter and receiver. These were supplied initially in Bedford 3 ton trucks.
An integral part of the C50/R236 setup was two synthesizers, one for RX one for TX. These were flat oblong boxes on top of the C50 with one on top of the other. On the front of each synthesizer was a panel which had five or six knobs. Each knob was calibrated in MHz. The frequency one wished to work was set up on each of the synthesizers. The line equipment, One plus Four Number Three which I mentioned, was connected to the communications center with a quad cable, just as we had done with the previous Larkspur C41/R222 combination. The communications centre was comprised of four, Bedford 3 ton trucks. Fitted in those trucks were various teleprinters, a cryptography kit, which at that time would have been a BID kit and the telephone exchange. In some armoured units, the radio and line equipment would have been mounted in FV439s, which were the signals version of the FV432 APC then on issue.
VEHICLE BODY
The box body was on the rear and in the middle between the radio body and the cab were two "ONAN" generators of US manufacture. Each could be slid out on its respective side. These were of American manufacture and were electrically started with just one switch! LUXURY! Imagine how good this was after having used the Coventry Climax generators which you had to hand crank and were mounted in a trailer which meant hard work in placng and camouflaging it. Each vehicle had a Clark mast mounted by the cab which was raised and lowered hydraulically. A spare was carried in the radio box body.
Another set used with Bruin was the Siemens C70. This was, I recall, a UHF set and difficult to tune. This was fitted in an Austin K9 radio vehicle, again with Clark masts, but had the old Coventry Climax towed generator".
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| C-50 transmitter of the C50/R236 combo. (Photo courtesy Wireless for the Warrior) |
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| R236 receiver of the C50/R236 combo. (Photo courtesy Wireless for the Warrior) |
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| C-70 radio relay set. It was used in Division and Corps areas. The frequency range was 610 to 960 MHz using FDM or TDM operation. RF output is 10W. This gave the relay station a range of approximately 25 miles. The set is a modified version of the Siemens FM 12/800 system. (Photo courtesy Wireless for the Warrior) |
Credits and References:1) http://www2.armynet.mod.uk/museums/royalsignals/postalcovers/baor.htm
2) Wireless for the Warrior http://www.wftw.nl/receivers/r236.jpg
3) Wireless for the Warrior http://wftw.nl/larkspur/c50.jpg
4) Wireless for the Warrior http://wftw.nl/larkspur/c70.jpg
Dec 18/11