There is no substitute to visiting Brooklands Museum and seeing the equipment first hand, but ahead of that visit, or for those that cannot come here, we offer some basic information on equipment connected to the collection (More images will be added as time allows).
The R1082 (pictured below) is a general purpose airborne HF receiver designed in the mid 1930s by STC. It was used together with the companion transmitter T1083 in early versions of light and heavy bombers including Fairey Swordfish and Battle, Handley Page Hampden, Armstrong Whitworth Whitley, Vickers Wellington and the Short Stirling. The R1082 was replaced by the R1155 in the beginning of the 1940s but continued in use in some cases until the late 1950s. At the outbreak of the war in 1939, the R1082 was one of the main receivers used by Royal Air Force, in spite of its technology being all but obsolete at that time. They were also used in air-sea rescue launches and after being phased out of the aircraft they were used for ground communication. Receiver Data The R1082 is a simple regenerative receiver (TRF) with 5 valves plus a protective diode across the antenna input. The first stage is an RF amplifier pentode, followed by a triode detector with positive feedback, two AF amplifier triodes and another triode as AF output stage for headphones. The equipment also provides intercommunication for the crew. The receiver covers 111KHz to 500KHz plus 3MHz to 15MHz in 14 bands with interchangeable coils, and it can be used for CW and R/T. The coils come in pairs, aerial (input) coil and anode coil for the RF stage. For full frequency coverage there are 28 coils in a special carrying case. The lower frequency bands can be used for D/F (direction finding), using a D/F add-on and a loop aerial. The receiver is constructed on a metal front panel to which all the circuits are mounted, the receiver case is of wood.
The receiver is a two-hand device with one hand on the tuning knob and the other on the feedback knob, and it needs a skilled operator to do a good job. The dial is only marked 0-100, and the operators made their own calibration charts for each individual receiver they used. The positive feedback is inductively coupled from the detector output to the RF anode coil. The degree of feedback is regulated with a potentiometer changing the RF gain. Close to the self oscillation point the positive feedback gives high gain. The receiver sensitivity is quoted as 25uV for a usable audio output. In the aircraft the receiver was fed by a 2 V 20 Ah lead acid accumulator for the LT (current 1.15 A), and a 120V battery (or dc generator) for the anodes (current around 13 mA). The receiver measures 27 cm x 29 cm x 23 cm (w x h x d), and the weight is a little under 7 kilos with two coils. Pictured below is a refurbished R1082 and the R1082 inside the Brooklands Wellington, rescued from Loch Ness
The R1155 (pictured below) was developed in the very late 30s for the RAF and entered service in 1940. It was a vast improvement over the existing equipment and was frequently retrofitted to aircraft with previous generation equipment. It was not developed as a straight communications receiver but was part of an aircraft system intended for both communications and direction finding, and therefore had circuitry and controls for D/F (Direction Finding). Only headphone output was provided, as loudspeakers were not practical in an aircraft with four roaring Merlin engines! The set was powered externally from the aircraft electrical systems.
It was used together with the companion transmitter T1154 (also pictured below) in a wide range of aircraft including the Lancaster, Halifax, York, Varsity, Mosquito, Valetta, Shackleton and Wellington. The complete system for heavy bombers included two R1155s (one for the radio operator and one for the navigator) a T1154 transmitter, an intercom system for the crew and three aerial systems.
The design is a single conversion superhet receiver covering the range 75 kHz to 18.5 MHz in five switched bands (these bands differed according to the model variant). The valve line-up is First RF VR100 / KTW63 vari-mu pentode, Mixer/oscillator VR99 / X65 triode-hexode, 1st IF VR100 / KTW63 vari-mu pentode, 2nd IF VR100 / KTW63 vari-mu pentode, 1st audio amp and detector/audio VR101 / DL63 double-diode/triode, BFO oscillator and AGC detector valve VR101 / DL63 double-diode/triode, Tuning indicator valve (VI103 / Y61) making a complement of 7 valves for the communications circuit. There is also a D/F circuit which used 2 triode-hexode (VR99A / X65) valves and 1 double triode (VR102 / BL63) valve. The magic-eye was shared between the communications and D/F circuitry.
The R1155 has a peculiar power requirement in that the 220V HT is floating. The set acts like a potential divider with the valves and screen supplies acting as one part, and a couple of large resistors acting as the other part. The middle of the potential divider is connected to the chassis, as is one side of the heater supply. The -ve side is used to for the valve grid bias supplies. With a supply voltage of 220V, the +ve HT line is at 184V to190V and the -ve HT line at -36V to -28V. The actual voltages depend on the setting of the RF gain and the particular values of the resistors. If the RF gain is high, the -ve bias on the valve grids is low and the valves conduct, lowering the voltage drop across them.
It continued essentially unmodified through its production life, apart from the addition of various traps to counteract interference from RADAR and MW stations. There were problems with the original tuning knob and Ekco developed an improved epicyclic slow motion drive, which was fitted as a replacement to many existing sets. The BFO valve tended to overheat and the problem was solved by making a hole in the BFO compartment cover to let the heat out. Approximately 80,000 R1155s were manufactured. The receiver sensitivity is quoted as 9 to 10µV for a usable audio output.
The T1154 (pictured below) was developed in the late 1930s for the RAF and entered service in June 1940. Over 80,000 were made before manufacture finally ceased in 1950. It is immediately recognised by the brightly coloured control knobs. The transmitter was designed by Marconi’s Wireless Telegraph Co at the aeronautical laboratory at Writtle. The design was typical of the innovation at the time and used the then new dull emitter filament technology for the two large power amplifier valves. The transmitter provided telegraphy and telephony with very good speech quality. It was used together with the companion receiver R1155 in a wide range of aircraft including the Lancaster, Halifax, York, Varsity, Mosquito, Valetta, Shackleton and Wellington. Transmitter data The T1154 contains 4 valves and is a variable frequency, master oscillator/power amplifier type of transmitter and is capable of generating a radio frequency (RF) output power of 45 to 70 Watts on CW (morse) and 14 to 17.5 Watts on speech and MCW. It had slightly different frequency coverage to the receiver using three or four switched bands and typically covers 0.2- 0.5 MHz, 3.0 - 5.5 MHz, 5.5 - 10 MHz. The 4-band models split the bands slightly differently and provided coverage up to 16.7 MHz.
Transmit modulation modes are: Amplitude Modulation (AM) for speech plus Continuous Wave (CW) and Modulated Continuous Wave (MCW) for Morse code transmission. The peak modulation is approx. 70 per cent using suppressor grid modulation on both MCW and R/T. The microphone used was either a Carbon granule type or electro-magnetic, using sub-modulator A1134 or A1134A. The valve line-up is Master Oscillator, sidetone and modulator - two VT105 indirectly-heated triodes; RF Power Amplifier - two VT104 directly-heated pentodes. The Antenna System was a fixed wire aerial for HF frequency ranges and a long wire trailing aerial for MF frequency ranges. In airborne installations, both receiver and transmitter were powered by two rotary transformer power supplies which were driven from the aircraft electrical system of 12 Volts or 24 Volts.
One transformer unit provided the high tension (HT) and low tension (LT) supply for the R1155 receiver and the LT supply (6V at 4A LT plus 6 volts at 2.5A for the keying relay) for the T1154. The high voltage HT supplies for the transmitter (1200V at 200mA) were provided by a separate rotary transformer unit. The transmitter measures 17 1/2" wide, 16 3/8" high, 11 1/4" deep and weighs 46 lb 10oz. Pictured below is a T1154 and companion R1155
Receiver P.C.R. No 3
The Portable Communications Receiver Type PCR (pictured below) was the first model in a series of general purpose receivers used primarily by the British Army and other Allied Armed Forces from 1944 until the late 1950s. Many such receivers were also to be found in aircraft ground stations throughout the world with various versions covering long wave, medium wave and short wave bands. The set was also supplied by the RAF to Resistance Groups in Norway, Holland and France. The equipment was designed by Pye Ltd in Cambridge in 1943, the drawings finalised in March 1944 and the design subsequently manufactured by a number of companies including Pye, Philips Lamps and Invicta Radio. The PCR is often described as a forces welfare receiver (its post war role) and frequently seen in NAAFI premises. War-time employees of Pye Ltd in Cambridge have described the equipment as a portable communications receiver or "Invasion Receiver," for use by the British Army forces in Europe after the Normandy landings to receive military progress broadcasts as they moved across Europe. It is believed approximately 16,000 units were manufactured in total.
Typical frequency coverage is 570 - 190Metres, 2.3 - 7.3MHz, and 7.0 - 23MHz although some versions also covered 2100 - 850 Metres, 570 - 190 Metres and 5.8 - 18MHz. The valve line up varies between models - the sets have one RF (radio frequency) stage (EF39), a Frequency Changer (X61/ECH35), two IF (intermediate frequency) stages (EF39's), a Double Diode Triode ( EBC33) and an output stage which is either an EL32 or 6V6.
These sets form the basis of a very cheap short wave receiver. They do not have a BFO, but they have plenty of room for an inbuilt power supply and BFO if required, with a "spare" valve hole already cut in the chassis. Other variations use an external loudspeaker and have slightly different audio input/output facilities. The PCR series are all externally powered from a separate mains PSU or a 12 Volt dc vibrator unit. The equipment front panel is usually finished in black wrinkle paint and the set mounted in a gloss black painted variant of the WS19 case. Due to the inclusion of the standard WS19 mounting slots in the case sides, the set can be carried in the standard WS19 carriers. Dimensions are 17 x 10 x 8ins/432 x 254 x 203 mm (WHD).
Transmitter ST23 and Receiver SR23
The Transmitter type ST23 and receiver type SR23 (pictured below) are a matching pair of VHF equipment types designed and manufactured in the UK by STC (Standard Telephones and Cables Ltd). They were used in a number of aircraft during the late 1950’s and early 1960’s including the Comet, Vanguard, Viscount, Convair 210 & Argosy.
They are typical of a new generation of airborne (and navigation) VHF communications equipment designed in the 1950’s. Instead of a complete transmitter and complete receiver having to be located in the aircraft cockpit, it became possible to “remotely control” the main equipment with just a Control Unit in the cockpit and allowing the main equipment to be located elsewhere in the aircraft. These are among the first generation of equipment to use modern miniaturisation techniques including transistors and PCBs (printed circuit boards).
The frequency band covered is 118 – 135.95MHz giving a total of 360 channels at 50kHz spacing. The RF (radio frequency) output is 20W.
The frequency band covered is 118 – 135.95MHz giving a total of 360 channels at 50kHz spacing. All spurious responses are at least 90db down (a major advance on previous designs and still typical of 21st century equipment).
A Control Unit is available to cover either the whole band of 360 channels or only the communications band. Power supply requirements are 115V 400Hz single phase AC or 28V DC. The control unit shown below is on from a Viscount
Remote Control Heads
Pictured below are some Remote Controllers that can be used to control all the radio communications equipment on board an aircraft. The upper unit set on 118 and 136.9 MHz is a Gables G-3837-02 that controls the VHF equipment used for short range communications (to local airport etc.) and the lower unit a Gables G-3751 controls the HF equipment used for long distance communications (for company traffic to home base etc.)
The complete unit controls a total of 4 transmitters and receivers (2 on VHF and 2 on HF) each with its own individual Frequency selection plus, on HF, Mode (AM or SSB) and RF Gain. It should also be noted that due to “standardisation” between manufacturers, it is not necessary to have the same make of Control Unit as Receiver or Transmitter; for example the Control Unit could be manufactured by Gables Engineering and the Receiver and Transmitter could be manufactured by STC or Collins etc.
Both pictures show units that were used in British Airways' Concordes but are also typical of equipment fitted to a wide range of aircraft during the 1970’s and 1980’s including the Vickers Viscount, Vickers VC10 and BAC 1-11.
Transmitter/Receiver Unit 618T-3
The Transmitter/Receiver Unit 618T-3 (pictured below) is a combined HF Transmitter, Receiver and Power Supply Unit designed and manufactured in the USA by Collins Radio Company. Manufacture started in 1961 and they were still in use until at least 2012. There were military versions used by the RAF, Fleet Air Arm and Army in addition to civilian versions. They were standard fitment to a number of aircraft including the Avro Vulcan, Concorde and VC10. The equipment is also known under its NATO part number TX/RX5821-044. Many thousands were manufactured. This version of the equipment is different to that produced only 20 years earlier in that the all the various high voltages needed for different stages of the transmitter are all an integral part of the equipment.
The frequency band covered is 2.0 – 29.999MHz giving a total of 28,000 channels at 1kHz spacing. The operating frequency is indicated directly in a digital-type presentation on the associated Control Unit. Frequency stability is quoted as 0.8 parts per million per month and the typical channel change time is 8 seconds (up to a maximum of 30 seconds) including the associated matching Antenna Tuner. The nominal RF (radio frequency) output power is 400W PEP in SSB (single sideband) mode or 100W in compatible AM mode. It is also capable of transmitting in CW (morse) and data modes. The transmitter comprises a total on 13 valves inc a pair of 4CX250s in the PA (Power Amplifier). It is capable of operating in ambient temperatures between minus 40deg C and plus 55deg C continuously or up to plus 70deg C for maximum of 30 minutes.
The frequency band covered is 2.0 – 29.999MHz in 1kHz steps. Sensitivity is 1 µV for 10 dB S+N/N ratio on SSB and 3 µV on AM. All spurious responses are at least 80db down and selectivity is typical for an SSB receiver being 2.85 kHz wide 6dB down and 6.0 kHz at 60 dB down.
A Control Unit is available to cover the whole band in 1kHz channels although there is also a version capable of switching in 100Hz channels. As may be expected, power supply requirements are heavy (!) requiring 28V DC at 35amps and 115V 400Hz single phase AC at 1 amp. The equipment measures 10 1/8" wide, 7 5/8" high, 22 3/16" deep and weighs 50lb.