Clansman (military radio)

A late introduction to the Larkspur range, its original designation was A16 Lightweight HF Radio Station. Deployed in tropical or high temperature climates, it was powered by either a standard 12V battery that connected directly to the set or, if issued, a Leclanché battery that connected directly to the set. It was compatible with most D10 or R4 copper stranded antenna systems that were fielded at that time, examples being the Shirley, Jamaica, Half Jamaica and Yagi.

Despite not being of the Clansman family, its late introduction to service coupled with its Clansman equivalent, the PRC/RT320 not being ready, meant the PRC 316 survived for just over five years after Clansman was introduced. Once the PRC/RT320 was completed and fully fielded, the PRC 316 was rapidly withdrawn. Another reason cited for its retention was that it was relatively easy to operate and was inter-operable with the other HF Radios in the Clansman family.

Special Forces and STA Patrol man-portable, patrol level radio HF / VHF, half-duplex transceiver capable of burst transmission which was built in the United Kingdom by MEL. Features include key-pad entry of frequency, mode and data with digital LCD display; 10 pairs of pre-programmable channels; half-duplex operation with the option of transmitting and receiving on different channels; the option of using the removable pocket-sized BA-1304 electronic message unit (EMU) to transmit and receive short data communications; fully automatic antenna tuner which can be remoted up to 50m from the set using standard co-ax cable; self-test facility. power output of 50 watts PEP on high power setting with an adjustable low power of 2–5 watts. Frequency range 1.5–40 MHz with upper sideband, data, or CW modulation.

An HF/USB/AM/CW transceiver built by Plessey and issued down to company level. The set operates in the 2–29.9999 MHz range with a possible 280,000 channels.[1] RF power output is a selectable 3 or 30 watts.[1] Derived from an earlier prototype known as the B20,[2] the PRC 320 can be used as a manpack (backpack) or vehicular radio and replaced the Larkspur Station Radio (SR) A13 SR C13 and other HF radios in service with the British Army.

The PRC320 can be used with a number of different Clansman antennas that are supplied with the set; a 2.4m whip antenna is supplied for portable manpack operation using HF groundwave communication with a range of up to 30 km (19 mi). Alternatively a dipole antenna can be used for HF skywave operation with a range of up to 320 km (200 mi).[1][3] The set includes a built-in Antenna Tuning Unit (ATU) which electrically matches the whip antenna length to the radio frequency in use. The ATU can also match any other wire antenna to the operating frequency. The set together with its ancillaries (batteries, cables, audio gear and antenna parts) together make up the complete equipment schedule (CES).[1]

The use of morse code and later data transmission and reception could extend the range and add to the versatility of the UK/PRC 320. A number of data entry devices were produced as add-ons such as MEROD, TDED and Kipling.

Clansman HF sets continued in use by the UK's Cadet Forces until c. 2015.[1][4] Many of the sets found their way into amateur service after the Clansman system became obsolete.

A vehicle-borne high-frequency (HF) transmitter-receiver used for inter-company communications outside of the normal working range of the VHF forward area nets; it can also be used dismounted from a vehicle as a ground station with an external power supply or batteries and antenna system. It was also used for rear link communications up to brigade level and administrative radio nets.

The set uses USB/AM or CW with an RF output of 20–30 watts. It was manufactured by MEL at Crawley in Sussex and replaced the Larkspur SR C13 and C11 R210 HF Vehicle Stations.

The radio is issued together with ancillaries to make up the operating station, including a power cable, antenna tuner unit, coaxial cables and antenna wires. Other accessories such as the selector unit radio frequency (SURF) were available. The SURF, when tuned, allowed more than one set to be operated from the same position without interfering with each other.

The standard antenna tuning unit used with the UK/RT 321 is the Tuning Unit Radio Frequency (TURF) 25 watts. This could be used either attached to the set, or remotely, depending on which antenna configuration was used.

A VRC321 station with the addition of a 300 Watt peak envelope power (PEP) linear amplifier (ARF 250W) and appropriate high power antenna tuning unit (TURF 250) manufactured by MEL of Crawley, Sussex.

An intra-section level portable VHF FM transceiver. Built by Racal BCC. RF power output is 0.25 watts. Units supplied to the British Army operate in the 37–46.975 MHz range, voice (FM) transmission Mode and 25 kHz channel separation. A high power (2 Watts) output version was also available and any 10 MHz block in the range 30–76 MHz could be supplied. Worn in a holster on the chest or back. The PRC349 was added to the Clansman family in 1972.[5]

A short-range VHF set covering 30 to 59.975 MHz. RF power output is 2 Watts.

An intra-platoon level backpack VHF FM transceiver. Built by Racal BCC. The PRC 351 has 4 watt RF power output, and operates in the 30–75.975 MHz range with a possible 1840 channels spaced 25 kHz apart. This radio is also capable of being mounted on a vehicle in conjunction with the TUAAM.[6] The PRC 352 is identical, with the addition of a 20 watt RF amplifier and can be used as a ground station.[7]

A vehicle-mounted VHF FM transceiver built by Marconi Space and Defence Systems. The frequency range and channel separation is the same as the 351/352 with output power settings up to 50 W.[8] Antenna systems are provided to provide improved performance in semi-static situations such as an elevated broadband vertical dipole mounted on an 8-metre mast.[9] The VRC 353 is also capable of data transmission and when used in conjunction with an add-on unit (Digital Master Unit) provides a medium level secure speech network.

The VRC 353 was notable as the only set in the Clansman family to partially employ thermionic valves - a single conduction-cooled tetrode as the transmitter power amplifier which is always in use even at the minimum 100mW power output, and two wired-in pentodes as RF amplifiers in the receiver section. It is often asserted that this was done to provide protection against Electro Magnetic Pulse (EMP) damage arising from a nuclear weapon strike, but was in fact necessary (at the time of design) in order to meet the required specification for dynamic range and adjacent channel performance.

A portable backpack or vehicle mount VHF to UHF transceiver built by Raytheon. The frequency range is 30 MHz to 390 MHz. AM and FM modes enabling compatibility with airborne units in the 118 MHz - 149.975 MHz and 225 MHz - 390 MHz aircraft radio bands. Unusually for a military radio, it can also work in duplex modes. Power settings are 2 watts on low power and 7 watts on high. It has interfaces for GPS.

A forward air control UHF AM transceiver. Built by Plessey. Operates in 225–399.9 MHz range with 50 kHz steps for a possible 3500 channels. RF power output is rated at 2.5 watts.

Used in conjunction with the "Harness" point on VRC 353 and VRC 321 units, to operate 2 or more sets as a ReBroadcast ("rebro"). This quasi repeater function allows two or more networks, on different frequencies, to be combined, effectively increasing the ground size of the net. For instance, a vehicle using whip antennas may only be able to communicate 30 km; though placing a rebro vehicle 30 km away could extend this to 60 km by re-broadcasting the signal on a second net. On US systems, this functionality is/was called RETRANS (for retransmission).

A Digital Master Unit or DMU is used to provide digital communications and to provide secure encrypted communications on a VHF network, when working to similarly equipped radios. This required additional equipment such as the BID 250 and associated Crypto key material.

A SURF (Selector Unit Radio Frequency) is used to prevent interference to operation of the radio sets. The SURF is an electrical filter, designed to reject unwanted interference from other radios when operating in close proximity to each other. The SURF is tuned using a manual control on the front of the unit, so that only the frequency in use, and those close to it, are accepted by the set. A Range of SURFs were provided for attachment to the VHF PRC350, PRC351/2 (SURF 4 Watt) and also the HF PRC320 (SURF 12 Watt) and VRC 321 (SURF 25 Watt).

A TURF (Tuning Unit Radio Frequency) is an Antenna Tuning Unit or ATU. It is used to artificially lengthen the antenna (or tune it) Often at HF wavelengths for example an antenna would be physically too long to attach to a radio without affecting portability and manoeuvrability. A shorter vehicle whip was more practicable and also field antennas were constructed with for example, vertical radiators constructed using the Racal 8 or 12 metre masts. Because these were an electrical compromise, they had to be tuned by use of a TURF (or electrically matched to the set). The TURF 25 Watt (a separate unit to the radio) is considered mandatory when using the VRC321: it tunes both unbalanced, end fed wires and whips and also balanced antennas such as the dipole.

An antenna tuning unit is built into the manpack PRC 320. The TURF requires users to manually tune the antenna, unlike the VHF TUAAM which is an Automatic Tuning Unit.

A TUAAM (Tuning Unit Automatic Antenna Matching) is an ATU which matches the standard vehicle antenna at VHF and which is used mainly with the VRC 353 and PRC 351/2 (when used with the clip-in kit and mounted in a vehicle). The TUAAM automatically tunes the antenna, and artificially shortens it rather than lengthening it, but essentially it performs the same function as a TURF. The TUAAM was a commercial product of Racal-BCC (BCC 543) and was adopted after the original SRDE design failed trials testing. Note that the actual TUUAM is fitted inside a 'Wing Mounting Box' which itself is fitted to a special mount, permanently fitted to the host vehicle.

An elevated end fed dipole for use with the VHF Radio to extend the range when mounted on an 8 or 12 metre Mast.