Radar Systems (1939 - 1946)
Air Interception Radar (AI) (part involvement in 200MHz versions)
Chain Home Low Radar (part involvement)
Air-Surface Vessel Radar (ASV) (part involvement in 200 MHz versions)

From 1939 onwards, Pye Ltd made an important contribution to the early airborne radar by supplying amplifying units  based on an existing 45 MHz TRF television chassis using the revolutionary new EF50 valve designed by NV Philips in Eindhoven.

Work by the Government on airborne radar had started well before Britain joined the second world war and followed the design of the ground based Chain Home system.  Pye had designed a high gain TRF television receiver to receive the prewar London TV station which broadcast on 45MHz.  This was based on the Philips EF50 valve supplied by Mullard, the Philips UK subsidiary.  The Pye 45MHz TV receiver circuit was found to be an excellent basis for the Intermediate Frequency (IF) amplifier and detector stages of airborne radar receivers, due to the gain, bandwidth and selectivity characteristics.  Pye and Ekco supplied the early radar receivers before Ekco and AC Cossor became the main suppliers.

According to E.G. Bowen, Pye supplied over 12,000 of the 200 MHz  receiver units for the 200 MHz radar systems AI MKI, AI MKII, AI MKIII, AI MKIV and ASV MKI, ASV MKII and ASV MKIII.

Anti-Aircraft Radio Proximity Fuze (1940 - 1942) (conceptual and prototype design work)

Between 1940 and 1942, acting on their own initiative, Pye Ltd carried our pioneering experimental work on radio proximity fuzes for anti-aircraft artillery shells.  This work included the design, in-house manufacture and testing of suitable miniature thermionic valves.  

The proximity fuze was a miniature radio transmitter and receiver fitted in the nose of an anti-aircraft shell, which detonated when close to the aircraft.  This required components which could withstand the shock of the shell being fired from the gun.

 In 1942 details of the early work on proximity fuzes were handed over to the USA by the Tizard Mission, along with the secrets of the Magnetron Radar valve and the Jet engine.  Implementation of the proximity fuze concept was finally achieved by the Americans near the end of the war.  See image of USA MK45 radio proximity fuze below right.  This operated at approx 225 MHz.

Time Scales:  1940 - 1942
Standard frequency range: TBA
Transmitter RF output: TBA
Primary model variants: TBA

Wireless Set No. 18 (1940)

Wireless Set No. 18 was the first volume production man-pack radio station for the British Infantry.  It was based on a design by the Government Signals Experimental Establishment (SEE) but improved on by Pye Limited.  The rapid finalization and production of the equipment appears to have been stimulated by the experience of the British Expeditionary Force (BEF) against the German forces in France and loss of equipments in the Dunkirk evacuation.

The equipment consists of separate tuneable transmitter and receiver modules mounted in a back-pack style carrying case, complete with integral battery mounted in the base of the case.  A sectional vertical rod aerial was used mounted on a base at the side of the case.  Alternatively a long wire ground aerial could be used to make the operator and station less conspicuous.  A pair of metal flaps and folding canvas hood provided water protection to the front of the unit.  The equipment was designed to be carried by one man and operated by a second.  See photo of equipment in use.

The valves used were relatively fragile 2 Volt filament types.  These sometimes limited the operational use of the equipment when (according to Pye Limited employees who conducted post-events analysis) the internal valve filament support springs fractured during parachute drops, as in Operation Market Garden near Arnhem.  See internal view of transmitter and internal view of receiver.   This particular equipment illustrated was manufactured by Invicta Radio, another company operated by the Stanley family, owners of the Pye Group at the time.

Production life: 1939 - 1945
Standard frequency range: 6 - 9 MHz
Transmitter RF output:  0.25 Watt
Primary model variants: Wireless Sets No 68R, WS68T, WS68P covering lower frequency ranges

Extract from technical manual: Yes, to follow

This small VHF hand held radio using miniature wire-ended valves was designed by Pye Ltd in 1942 to allow Infantry Soldiers to communicate with Tank Crews who already used the 230 MHz "B" set of Wireless Sets No.19 for tank to tank communication.  It was intended to have a similar range to that of the tank WS19 "B" set and to fulfill the reciprocal requirement of the specification for Wireless Set No. 24, in other words for the Infantry to be able to talk back to the tank "B" set.  Its use was formally proposed in a secret  report by Pye Ltd to the Ministry of Supply in 1942.

However, the Ministry preferred to make use of an extra Wireless Set No. 38 mounted in the AFV to talk directly to the other WS38 equipments already in use by the Infantry Soldiers.  Eventually a special version of WS38 (WS38AFV) was configured to integrate with the WS19 control harness system mounted in vehicles.

It is believed that early in the war, samples of the Pye VHF hand held set were supplied to the USA by the Tizard Mission.   After the War, the equipment was featured in a short film demonstrating the future use of personal radio communications by the general public.  See image at right below.  One of the designers is pictured here posing with the equipment in 1996.

RF Amplifier No. 2 was an external RF amplifier, used to boost the modulated transmitter output power from the"A" Set of  Wireless Sets No.19.  Depending on the frequency in use, the equipment model and the input drive power, output powers between 15 and 35 Watts can be obtained.

MKI and MKII models used four 807 valves in parallel but the later MKIII used only two 807s and a different bias arrangement in order to improve efficiency.  A large internal rotary generator was used to provide the 650 Volt HT supply, and from the MKII version onwards a fan on the generator also circulated cooling air into and out of the case via a filter mounted on the case back panel.  The complete amplifier consumed an additional 16 Amps at 12 Volts.

The RF Amplifier was usually mounted on top of the WS19, and for antenna matching used either its own special tuning unit, or the Aerial Tuning Unit Type J from Wireless Set No. 22.

A 24 Volt version of the RF Amplifier was later manufactured by Burndept Ltd.

More details and photographs to follow of the 24 Volt version.

Wireless Sets No. 22 was a general purpose low powered HF transmitter receiver intended for use by the British Army in non-armoured vehicles.  It could also be configured as a 3-man-pack load or for animal-pack use, and was also used on a transportable hand cart. It had a similar frequency range to WS19 and was intended to provide a similar performance, although the transmit power was lower.

The internal layout was similar to WS19 (although the circuits were quite different) except that WS22 has an internal roller-coaster aerial tuner mounted where the WS19 had the VHF "B" set and intercom amplifier.  See internal top side view and underside view.  The front panel layout of WS22 was very similar to the original prototype WS19 MKI.

WS 22 uses an external vibrator power supply to generate about 300 Volts dc from a 12 Volt battery source.  See internal view of PSU.

Royal signals records show that a total of 55,000 units were manufactured by Pye Ltd and  the Mitcham Works factory of Philips Lamps.

For certain applications requiring either moisture proofing or airborne operation, WS22 was replaced by Wireless Set No. 62, (which was originally designated WS22 MK2) although the British army continued to use WS22 for general purpose low power mobile applications until the end of the 1950s.

WS X32 was a series of experimental radios used by the British Army to evaluate frequency modulation (FM) in the HF bands against the existing amplitude modulation (AM) method used during World War II.

The USA pioneered FM in the late 1930s and much of the US forces short range land warfare communications used this mode from the beginning of their involvement in World War 2.

More to follow.

A lower frequency version of Wireless Set No.18, covering 1.75 - 2.9 MHz or 3 - 5.2 MHz.

The equipment was  introduced in 1943 in order to permit longer range communications by using lower frequencies than used by the standard WS18.

More to follow.

Wireless Sets No. 62 was a low power, short range, vehicle station HF transmitter & receiver.  The frequency range was 1.6 to 10.0 MHz in two bands.  It was intended as an interim, but  lighter and water proof replacement, for Wireless Set No. 22 MKI, which had been in service with the British Army since 1942, and which was due to be replaced by Wireless Set No. 42.  However the WS42 project was abandoned and WS62 became a permanent equipment.  It was used by the British and Australian Armies, and possibly by the Canadians.

The equipment, which was designed by a team including Bill Pannell and Dr. Latislav Lax, was of mainly aluminium construction, was water resistant, semi-tropicallised and would float.  It weighed approximately 30lbs, and was used as a vehicle mounted mobile station, a man-pack set and as an animal-pack set in both European and Far East campaigns and later in the Korean War.

The transmitter power output was approximately 1 Watt into a vertical rod or long wire antenna.  The equipment was powered by a miniature rotary transformer mounted inside the case and supplied from external 12 Volt batteries.  In 1963 a transistor dc-dc converter was designed to replace the rotary generator.  The example pictured, which dates from 1953 is fitted with the transistorised PSU.  See inside top view and underside view.

A separate unit, Crystal Calibrator No. 10, was later used as a frequency setting aid with WS62 (and with the C12).  From the Publication Department master handbook copies,  Bill Pannell is known to have been the technical design authority for Calibrator No. 10.

Wireless Set C12 was originally designed between about 1948 and 1950 as a private venture by Pye Ltd to replace the 'A' set and intercom functions of Wireless Sets No. 19, but initially was not considered for use by the British Army due to the War Office preference for a new concept of hermetically sealed, water-proof equipments (which later came to be known as Larkspur).

The official replacement equipment for WS19 was Station Radio C13 from supplier BCC Ltd, however, during the early 1950s when the C13 development program was clearly going to run late, the Pye C12 was evaluated and later adopted by the British Army as a temporary substitute for Station Radio C13 in armoured fighting vehicles.

Due to the slowness of the C13 program and subsequent defence cut-backs affecting the purchase of new equipments, the C12 actually remained in service until the late 1970s.  Although most C12 equipment bear the date 1955 it was first demonstrated by the Army in July 1953 at a 3 day exhibition held at  the Royal Aircraft Establishment, Farnborough by the Radio Communications and Electronic Engineering Association and sponsored by the Ministry of Supply.  It is pictured at right fitted into a Saracen armoured vehicle during its military trials.

The equipment was constructed along similar lines to WS19, WS22 and WS62, and had the same overall external dimensions.  It consisted of a waterproof main transceiver unit, a separate power supply unit and an external aerial tuning unit.  The equipment could be connected to either WS19 type or Larkspur type control wiring harnesses.  It is pictured above with the WS19 type drop lead adapter connected.  See inside top view and underside view.

The frequency range covered was 1.6 to 10.0 MHz, and the equipment had a two-channel electro-mechanical  'flick' tuning system.  The main set used switched main tuning capacitors, each with its own colour coded dial mechanism.  The ATU had twin tuning inductors switched by relays under control of the radio unit. Transmit RF power output was 5 - 7.5 Watts AM at 95% modulation and 4 - 8 Watts output on CW. The equipment was intended to work into vertical rod aerials of length between 8 and 32 feet, but would also operate into a 100 foot wire.  It was claimed that due to the high level of modulation achieved, the station was equivalent to a WS19 and HP Amplifier No. 2 combination (which gave about 25 Watts RF output, although with low level modulation).

Different external power supply units were provided for 12 Volt systems or 24 Volt systems.  Each used an electro-mechanical vibrator to provide 250 Volt HT supplies to the receiver, and a rotary transformer to generate the 400 Volt 140mA supply for the transmitter.  Early 24 volt PSUs ran sufficiently hot that a manually controlled cooling fan had to be added.   Transistorised versions of both PSU were introduced in the early 1960s. The Crystal Calibrator No. 10 from Wireless Set No. 62 was used as an external frequency reference for the C12, but modified slightly to compensate for the different HT supply voltage.

The C12 was manufactured for Pye Ltd at a facility in the Richard Garrett Engineering Works, Leiston, Ipswich UK, and later by Pye Scottish Telecommunications, Airdrie. 

V2.0 - Date 11-12-2005 updated 30-01-2010

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