The Microwave and Tropo scatter system
During the late sixties, the Regiment took over a comparatively new role that of Microwave Radio Relay links and a Tropo Forward Scatter system. To meet the demand a new troop was formed in 1968 Microwave troop.
The troop consisted of a TE trained Officer and a TOT supported by a Foreman of Signals and an NCO and several technicians at each location. The hub of the system was based in RAF Changi. Most of the equipment had been pre- installed at RAF stations throughout the island and Malaysia.
The main circuits were concentrated at the hub but there was a further concentration of circuits at Bukit Gombat. The northern circuit ran from Changi through Seletar and the naval base to Bukit Gombat while the southern route ran from Bukit Gombat via Tengah, Jurong and Tanglin to Changi while a further route ran from Bukit Gombat via Amoy Quee, and Paya lebar to Changi.
The Malaysia link from Bukit Gombat to Western Hill was by Tropo and then to Butterworth by microwave.
In the mid 1960’s with smaller numbers in our armed forces thoughts were turning, as always, to reducing costs. Attention had been drawn to the fact that all three services ran their own long-haul radio links from the UK to overseas theatres and it was concluded that single links carrying traffic for all three services would suffice. This was at a time when satellite communications were being developed and this appeared to offer, in the longer term, more reliable communication links with considerably higher traffic carrying capacity than the high frequency radio links then exclusively used for long haul communications. The whole matter of the provision of tactical communications for the armed forces was studied, proposals were made for the Rationalisation of Inter-Service Tactical Communications (RISTACOMM) and agreed.
Whilst the main effect was that the RAF would undertake the provision of long haul communications for all three services and Royal Signals would take over responsibility for all line-of-sight radio relay communication systems, there were administrative changes as well. The Chief Air Formation Signals Officer (CAFSO) posts, each with their own branches in Air Headquarters, were abolished and Air Formation Signal units came undefile:///C:/Users/john/Desktop/Build/imgs/jimmy.jpgr Army operational command. To confuse the issue Air Formation Signal units were retitled ‘Air Support’ and in late 1968 19th Air Formation Signal Regiment was re-named 19th Signal Regiment (Air Support).
In Singapore 237 Signal Squadron (DCN) had a long haul transmitter site at Chin Bee and receiver station at Amoy Quee. These were connected by line-of-sight multi-channel radio relay equipment to the General Headquarters (GHQ) signal centre at Tanglin. The RAF had a similar system with Headquarters, Far East Air Force (HQ FEAF) at RAF Changi with its associated signal centre connected via similar radio relay systems to the transmitter station at Jurong and receiver station at Chia Keng. By July 1968 Amoy Quee and Chin Bee had been handed to the RAF. Amoy Quee had, at this time, a satellite ground station trialling communications to the UK via low-orbit satellites and the RAF took this station into service as their main long haul receiver site thus freeing Chia Keng to be used as a radio-relay training site.
During this time a long term RAF project to connect the radar sites at Jurong, Singapore, and Western Hill, Penang, by a 372 mile troposcatter radio link was coming to fruition. The object was to surrender some of the hideously expensive civil private wire circuits between the two sites. With responsibility for manning the existing army sites plus the RAF sites plus the tropo scatter stations, it was foreseen that a troop some 120 strong would be required. In the meantime the RAF sites, including the Western Hill to Butterworth radio-relay link, were manned by personnel of 2 Signal Unit, RAF (2 SU), commanded by Fl Lt Mike Sawyer (later Sqn Ldr)
Whilst proposals for the establishment and formation of this troop, Microwave Troop of 1 Squadron, dragged on, Royal Signals personnel started to ‘drift’ in. First was a Foreman of Signals in February 1968, followed by others who formed a system control centre at Changi. Later (in June) the TOT from 237 Signal Squadron was attached and became Engineering Officer, 2 SU. There was a major problem ‘finding’ sufficient Radio Relay Technicians to meet this commitment (in other theatres as well as the Far East) and to free them to be trained at RAF Locking. It was not until some time later, after equipment had been released from Aden, that 8th Signal Regiment could undertake these conversion courses. In August 1968 the Regiment started to assume these responsibilities and release RAF tradesmen for re-deployment but it was not until May 1970 that the last Royal Signals technician arrived. The diagram below shows the layout of the microwave system in the early days of the transfer from RAF to Army:
The line- radio relay stations were equipped with Marconi HM314/315 radios operating in the SHF frequency band around 4.5 GHz as had the 10 Set of WW2 vintage before it. But whilst Post Office (sorry, BT) engineers would have been perfectly at home with these radios and the associated 24, 60 & 120 speech channel AT & E multiplex and associated sub-multiplex equipment, Royal Signals Radio Relay Technicians were trained to operate and maintain equipment of the BRUIN era: Ptarmigan was still in the planning stage and would not see the light of day for a further 12-15 years. They were trained on the C41 and, just coming into service, the C50 together with the American AN/TRC which was still lingering on, all operating in the VHP band. The B70 did work in the same SHF band as the HM 314/315 but. whilst Royal Signals Technicians were introduced to it, that set had limited application and was ainly used by Royal Artillery units. The channelling equipment could carry 3 or 4 speech channels, the radios worked in the VHP frequency bands. To them the military static radio-relay systems that they were taking over from the RAF around the world were pretty awesome!
The HM 314/314 equipment and associated channelling equipment was remarkably reliable, the most common problems being with the radio Heil Tube, 350 mW, output valves which were similar to those used in the 10 set and the B70. This made the provision of spare parts that little easier.
The 10 kW, REL 2600, Tropospheric Scatter radios, posed very different problems. They were procured in good faith and with the benefit of experience. The NATO funded ACE High communication system that linked radar sites, operation centres and airfields in a big loop from Cape Greco in Cyprus to Northern Norway used these equipments and the UK stations were manned by RAF personnel (manning of these also transferred to Royal Signals under the RISTACOMM agreement). Whilst this system worked reliably on frequencies around 900 MHz, day and night, the later models installed in Singapore and Penang caused constant trouble and never were we able to surrender the private wire circuits between the two sites. The technical problems were compounded by the design authorities not noticing hills some 4,000 ft high in the radio path near both terminals. Instead of shooting downwards perhaps 2° to the horizon, the aerials had to be aimed upwards by a similar amount to clear these hills giving an extra path loss of some 10 dB.
To give one example the equipments had a number of cooling fans (the figure 17 comes to mind) after a while the ball races started to seize. Why? The fan motors were clearly rated 110V, 50/60 Hz. The application of the law of Mr Kirchoff shows that such motors run appreciably faster when supplied from a 50 Hz supply than from 60 Hz. Simple solution; replace the ball races until a permanent solution is found. Not so simple. The ball races were not standard and not readily available locally.
Another problem. Because of the transmission path losses the transmitters had to be run up to full 10 kW to get a workable signal at the distant receivers. But a short length of 3″ co-ax feeder at the transmitter output was of reduced diameter to act as a ‘harmonic suppressor’. These, at both sites, started to fail due to internal arcing. To repair them they had to be taken apart and new parts fabricated on a lathe. That was a story in itself. Reduce the output power responded the technical authority, probably in desperation!
To return to the unit, when half of the RAF personnel had been replaced by Royal Signals, command was transferred to 19th Signal Regiment and Capt (later Colonel) Bill Roper took command of the troop. Until that time ‘pay parade’ was taken personally by one of the two officers in the unit. One would drive the nice blue RAF landrover around the eleven sites on the island accompanied by the unit Flight Sergeant – who carried a length or armoured co-axial cable as means of defence. When the unit formally came under Army command this practice came under scrutiny and hence forward two green landrovers were required with an Army (LEP) driver in each and two more LEPs in the back of each vehicle armed with Sterling sub-machine guns.
Whilst 19th Signal Regiment formally disbanded on November 15th, 1971, RAF Changi continued as an operational flying base until November 30th and members of Microwave Troop continued in post until then. Meanwhile the network had been handed to the Singapore Armed Forces and the Tropospheric Scatter system finally closed on September 1st and ‘the equipment disposed of locally.
It should be mentioned that the radio-relay system connecting the airfield on Gan Island with the DCN Transmitter site on the nearby island of Hittadu was also maintained by members of Microwave Troop flying from Singapore for routine maintenance work every six months or when major failures occurred. When 19th Signal Regiment disbanded the establishment at Gan was increased, the unit there became 605 Signal Troop (Air Support) under the command of HQ 3 Signal Group in Cyprus.
Check below for photos and archives of Microwave troop
Mike Wells Changi Troop and Microwave troop
Mike Wells was posted to 19 Signal Regt. twice.The first time to Changi Troop and later in the sixties to Microwave troop
Our thanks to Mike Wells for his Microwave Troop contribution
Microwave troop offices
Microwave troop offices and Technical centre at Seletar
Cpls Club RAF Seletar. Microwave troop wives.
Derek Ennis (RAF), Graham Dean, Eric Robinson, Hilary Robinson,
Taff Davies, Ann Davies, Dick Newton and Janet Newton
Microwave Troop Tropo link antennae and the equipment room
Tech at Work
Microwave Troop technician at work in the VFT Room
The Tropo Transmitter bay at Bukit Gombak
Not very glamorous but this is the main microwave terminal building at Changi
Tech Sgt on Duty
A technical Sgt. adjusts the Marconi HM 314/315 on the Microwave system
Microwave troop wives sports team
Can’t leave the girls out !
Mike Well's Family
Mike Wells wife and family living at Seletar Hills
Mike Well's memorabelia.
Mike Wells army driving permit
Microwave troop 1971