Notes on Cold War

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M Lambert

Radios of the Cold War (Canberra and Other Aircraft)
This Canberra article has been produced because it is noticeable that there has been very little written and recorded about early Cold War aircraft communications equipment and practices. Whilst no expert on this subject I was using them and there amongst these items on Canberras during the early 1960s. So, this is an effort to stir up some interest in the subject. Possibly a few souls may come out of hiding and recount their own experiences adding to the knowledge of this rapidly disappearing era. For example, if you want to find about airborne radios Google SCR 522 and there are many references - all from the USA. But Google 1985 and you get nothing relevant to later Cold War usage. Apologise in advance if there is too much or to little detail about the radio equipment, any comments that anyone cares to make, via the Webmaster, will be addressed. If you have an interest in recording your Canberra experiences please get in touch with the Webmaster.

As aircraft were phased through various upgrades there were many later items introduced that I am not familiar with. Accordingly this article is not a compendium or list of all Cold War radio equipment but just those bits of kit that were in use during my service. However, also included is a list of Radio type numbers which will, hopefully, help identify what belonged with what as well as help identify that tricky 'unknown controller' that appears from time to time.

The Canberra specifically is being covered here so, to provide an answer to a question that often crops up with regards to the Horizontal Aerials on the nose of the aircraft alongside of the Static Vents, they are Rebecca receiving aerials (Port and Starboard). Rebecca transmitting aerials are below the cabin floor forming a crossed 'V' shape. BABS Aerials were fitted in the skin of the rear hatch and also formed a crossed 'V' shape.

Rebecca was a pulse operated interrogation system used for homing, and also when working with BABS, for blind approach. Rebecca operated in the 174 to 240 Mcs range in conjunction with ground beacons. Superseded of course by the VHF ILS equipment fitted as standard to most airfields by the 1960s.

Much more information on Rebecca and BABS can be found by Googling.

Canopy VHF
Canopy Mounted VHF Aerial

Later VHF
Fuselage Mounted VHF Aerial

Rebecca Receiving Aerial
Stbd Side. Port side the same

Rebecca Transmitting Aerial
('K' Shape, forward)
BABS Transmitting Aerial
('K' Shape, rear)

VHF Communication 1950s Style
(Mcs = Mhz) To keep in with the period Mcs will be used here.

The wartime all-British designed Airborne VHF 4 channel T/R 1143 was copied by the Americans to become the SCR 522, (which they then sent back for us to use on the lease lend scheme incidentally). Following on from that there appeared a modular constructed VHF 10 channel set designated 1935/6. These were rapidly superseded by the 10 channel VHF 1985/6/7/8/9 series. Fitted in just about every RAF aircraft flying at that time.

These radios were not renowned for reliability, over the long term and failures were fairly frequent for all manner of reasons. Nevertheless they provided, when working correctly, good range and good speech quality, enabling instant communication with only a single control for channel selection.

In the early Canberra the 1985 and 1986 sets were fitted in the un-pressurised top hatch. Many a radio tradesman remembers having to crouch in this confined space (having first crawled on his hands and knees along the top of the fuselage) during set replacement or worse still a crystal change. Especially memorable if it was raining and when the locking wire used to lock the mounting tray securing wing nuts in place had a mind of its own, usually intent on drawing young blood.

Early days on VHF had most RAF stations on common frequencies Bomber Command had one on 103.86 Mcs. However as Radar and Talkdown services came on stream more frequencies came in to use for every RAF station. This proved a problem as the in use sets only had ten channels each and with the coverage of the 1985 being 100 to 125 Mcs, the 1986 125 to 145 Mcs and the 1987 100 to 145Mcs the need for frequent crystal changes on the sets became the curse of the Sqn radio section. Most RAF station electronics sections (commonly called The Gin Palace) had a crystal bank which was usually a vast steel locked cupboard (as if they were of any use to anyone else) shelved with hundreds of crystals. The required frequencies for a particular sortie would be phoned to the squadron by the Navigator (hopefully the day before the flight, but not always) these crystals then had to be collected and then transported to the squadron prior to a before flight inspection.

A simple crystal change becomes a real pain as the fitter had to find a working petrol electric set, get it towed or more likely get the tractor and tow it himself to the nominated aircraft. Trying to use and subsequent flattening of the aircraft battery was forbidden. Having established ground power, found a set of steps to get on the wing and with the radios warmed up the appropriate crystals were fitted in the correct holders and a retune carried out. A headset left over from WW2 would be used along with a microphone dangling and getting in the way would be used to check the set was working. No guarantees though. So how do you carry out a radio check on a VHF frequency that is only being monitored hundreds of miles away from a radio that would sometimes seem to tune correctly but on the wrong frequency. Very important to make sure that it was working otherwise the crew could get quite angry having flown for three or more hours only to find that they couldn’t contact their nominated Bombing range.

How did you go about this all important radio check on these temperamental radios? Well it was no good trying to check with the station's Air Traffic Control tower as they had even less choice of frequencies than you did. Most ATC communications in the 1950s were carried out on single channel 19 inch rack-mounted separate transmitter and receivers (type 1392 etc). Solution. With initiative working in top gear you rang the station's Radio Bay in "The Gin Palace". Request they listen-out after having re-crystalised and re-tuned a set in the bay to a similar frequency configuration and then carry out a radio check with you. Long winded and time consuming it certainly was and not always possible as the electronics section didn’t usually work after 17:00. It was not too bad though if you had a pair of aircraft going together on a sortie. You could then do an aircraft- to-aircraft check. All those ex-w/t Cold War mechanics will remember the sequence for checking between aircraft. Start at channel A (selected on the Type 382 controller) call 12345 then wait for the answer from the other aircraft, which would be 678910 (. . . if he heard you). Go to channel B and repeat, then C etc, and so on until all 20 channels (if your lucky) work. Next task (you're not finished yet) and specific to the Canberra, take out your magic bulb, (a PL259 coax plug with a bulb soldered to it), unplug the canopy horn aerial plug in your 259 and whilst holding the press to talk switch down on the spectacle select each channel in turn to make sure the transmitter output lit the bulb to the same level of brightness. You would be very lucky if this happened. No 1 VHF used the port horn canopy aerial and the No 2 VHF used the starboard one. When eventually you manage get back to the line hut to “sign up” the Chiefy would tell you that they had changed the aircraft and would you crystallise it back to standard and put the new crystals in the replacement aircraft. Usually timed to be about 17:05! So back to the tractor and order a late tea from the mess.

Although later versions of the same basic radio had larger channel selections available (up to 45), the VHF communications limitations were only overcome with the introduction of digital frequency selection.

Below is a series of photos showing the inards of the 1985/6 series. Going into technical detail regarding the set is outside of the scope of this article, but one thing that was unique was the use of a gearbox on the end of the dynomotor which was used to drive the crystal frequency selection mechanism. The 'clunk clunk' sound this made on channel change was the trade mark of this breed of radios.

Dynamotor Unit


Change Drum
Crystal Bank and
Channel Change Drum

Slide Bars
Channel Slide Bars

Top View
Top View

Transmitter Sub-Chassis 1

Transmitter Sub-Chassis 2

Under Chassis
Under Chassis View

ARC52 and PTR175
Introduced in the mid to late 1960s the American produced ARC52 had a huge impact on the operational effectiveness of both Air-to-Air and Air-to-Ground communication. Fully selectable frequency changing from 225 to 400Mcs and pre-set studs made the use of UHF much less of a burden both to air and ground crews alike. A pre-flight stud change could be carried out in the warmth and shelter of the cockpit with little chance for error (providing you didn’t change the frequency on the studs by looking at the frequency selector). Also there was a huge range of frequencies available and most stations had duplicate facilities on UHF and VHF. However for a short change over period the VHF sets were still used in conjunction with the ARC52.

Then came the introduction of the PTR175 and all its subsequent variants. This gave coverage from 108Mcs to 145Mcs in the VHF range and 225Mcs to 399Mcs in the UHF range all in one box. The introduction of this kit saw the withdrawal of the 1985/6/7/8/9 sets in front line aircraft, although they were still in use in some older aircraft well in to the 1970s.

These UHF sets equipped with suitably mounted aerials were also able to act as a direction finding devices suitable to locate downed aviators using Sabre Beacons on 243Mcs. Proving itself a very useful piece of kit for the Shackleton and Whirlwind SAR operators, they were very reliable in service with a temperature controlled fan in a pressurised steel container. The electronics, although still utilising some valves, were much more advanced than anything else the RAF had been used to. So, other than having to use the stirrup type pressurisation pump on the before flight to maintain the inside pressure, the radio tradesman's life suddenly got a lot easier.

But the equipment was very heavy requiring two men to safely install one in the top hatch of a Canberra, although some sets were fitted in the rear hatch which made things somewhat easier. Although the accompanying pictures are of the ARC52 series the external differences between the ARC52 and the PTR175 is the extra VHF aerial socket on the PTR175. Internal and technical differences go beyond the scope of this article.

Type ARC52

ARC52 Controller Fitted to Panel

ARC52 on its Tray in the Rear Fusulage

ARC52 Front Panel and Blower

ARC52 Junction Box and Muting Box

Type PTR175

PTR175 Channel Controller

PTR175 Controller Main Panel

PTR175 Channel Selector In-Situ

Marconi Radio Compass
There were other radio compass types available in the 1950s but the Marconi was known as the sub-miniature type, it found a home in aircraft where weight or space was a problem. Requiring, as ADF installations do, to have a loop and sense aerial, the Canberra had sense aerials fitted everywhere depending on mark and mod state. Most Canberra marks however had the loop fitted in the top equipment bay hatch. This location made it somewhat vulnerable to damage and shock loading if the hatch was inadvertently slammed down (by the wind of course). Initially designed with a motor driven rotating loop aerial (and yes, it had "Do Not Turn By Hand" stamped on it ) the unit was latterly fitted with a fixed electronically rotated loop.

Using valves that operated on 28 volts it generally proved a good piece of equipment, often responding to a gentle tap by the crew if it ceased to operate. Slightly archaic in that it had a speedometer type Bowden cable link between the frequency selector and the Radio Frequency (RF) Amplifier, it proved reliable, if a little stiff to tune in the extreme cold when the inner cable froze. Easy to use, it consumed very little power and the accuracy was good enough to rely on over long water stretches. (The kit was also good for gathering the latest rugby and cricket scores.) Being powered by a 28Volt system meant that it never relied on the dubious rotary 115Volt AC invertors to operate. First fitted to the New Zealand air race Canberras and then to those aircraft involved in Operation Grapple at Christmas Island, it eventually became a standard fit to most Canberras and remained in service alongside Decca for most of the Canberra’s service life.

Radio Compass Controller

Radio Compass Indicator

RF and IF Amplifiers

M. Lambert, 2008