WWII AN/APR-4 Search Receiver, Transmitter Block Museum, Ferry Road, RAF Bawdsey.
The Search Receiver was used on Aircraft and Naval Vessels. When supplied with all tuning units the system was used to determine the presence and measure the frequency of any radar or radio signals within the frequency range of 38 - 4000 Mc/s, determine what modulation may be present on these signals, give an indication of the relative field strength of these signals and monitor a transmiter.
The equipment was first used in 1944 as APR4, using octal tubes and acorns, but over the years the equipment was modernized, using miniature tubes (APR4Y) and a multi-band tuning head (CV253/ALR) the APR4Y had reached U.S. disposal sources by 1965. The APR4 utilized a 115/80v AC supply at 60-2000 cycles and also required 28vdc at 900ma to drive the tuning head motor, the APR4Y required 115vac at 380-1000 cycles as well as 28vdc. The Receivers are improvements on the former APR1 (Air Force) and RDO (Navy) Receivers. Plug in tuning units were used to cover the wide frequency range used, TN-16 38-95MHz, TN-17 74-320MHz, TN-18 300-1000MHz, TN-19 975-2200 MHz and TN-54 2150-4000MHz (a later unit CV253/ALR covers 38-1000MHz)
The main Receiver features a 30MHz IF channel, with provision for wide or narrow passband. There is provision for panoramic and video outputs for signal analysis. A BFO is provided for weak carrier detection and CW. The set has a calibrated IF gain control. High (8000 ohm) and low (600 ohm) audio outputs are provided. The APR4 has AM and CW detectors, while the APR4Y also demodulates FM.
RAF Bawdsey Radar Trust, Transmitter Block Museum.
The Transmitter Block is now a Grade II Listed Building and one of several structures on the former site of RAF Bawdsey that formed the first Operational Radar Station in the world, playing a vital role in the Defence of Great Britain during World War Two. First completed in 1939, the brick-faced Transmitter Block housed Electronic Equipment that sent the Radar Signal out through four 328ft tall Masts, their massive concrete bases are still visible.
The Transmitter Block fell into disuse during the 1970's and steady deterioration led to it being placed on the ‘Buildings at Risk Register’. Freeland Rees Roberts was appointed in March 2014 as Architects for the restoration and, with assistance from the HLF and Historic England, the building has now been completely restored. Inside a new interactive exhibition tracing the history of Radar was opened to the public in September 2017.
Extensive repairs were needed to the surrounding concrete Blast Walls using advanced techniques that will prevent further corrosion of the reinforcement, after careful patching and cleaning, the whole surface was coated with a clear microporous coating that reveals the colour and board-marked finish of the original concrete. This was followed by reinstatement of the Earth Revetments on two sides (the other Blast Walls have been left exposed) the flat concrete roof was completely removed and then replaced with a layer of insulation and a new waterproof membrane. A brick incinerator chimney thought to date from the Cold War Era was in poor condition and rebuilt in matching materials.
A new accessible lavatory block for visitors was prefabricated, clad in Corten steel and lowered into position between two of the Blast Walls, the air source heat pump has a similar enclosure. Internal and external decorations have been carefully matched to the original colours, leaving some of the original finishes and fittings visible. A new exhibition has been installed by PLB telling the fascinating story of Radar in all its detail and the building has now been re-opened to the public
In 2018 the project received a commendation from the RIBA Suffolk Craftsmanship Awards for Restoration and the project also won the 2019 Civic Trust AABC Conservation Award.
WWII AN/APR-4 Search Receiver, Transmitter Block Museum, Ferry Road, RAF Bawdsey.
The Search Receiver was used on Aircraft and Naval Vessels. When supplied with all tuning units the system was used to determine the presence and measure the frequency of any radar or radio signals within the frequency range of 38 - 4000 Mc/s, determine what modulation may be present on these signals, give an indication of the relative field strength of these signals and monitor a transmiter.
The equipment was first used in 1944 as APR4, using octal tubes and acorns, but over the years the equipment was modernized, using miniature tubes (APR4Y) and a multi-band tuning head (CV253/ALR) the APR4Y had reached U.S. disposal sources by 1965. The APR4 utilized a 115/80v AC supply at 60-2000 cycles and also required 28vdc at 900ma to drive the tuning head motor, the APR4Y required 115vac at 380-1000 cycles as well as 28vdc. The Receivers are improvements on the former APR1 (Air Force) and RDO (Navy) Receivers. Plug in tuning units were used to cover the wide frequency range used, TN-16 38-95MHz, TN-17 74-320MHz, TN-18 300-1000MHz, TN-19 975-2200 MHz and TN-54 2150-4000MHz (a later unit CV253/ALR covers 38-1000MHz)
The main Receiver features a 30MHz IF channel, with provision for wide or narrow passband. There is provision for panoramic and video outputs for signal analysis. A BFO is provided for weak carrier detection and CW. The set has a calibrated IF gain control. High (8000 ohm) and low (600 ohm) audio outputs are provided. The APR4 has AM and CW detectors, while the APR4Y also demodulates FM.
RAF Bawdsey Radar Trust, Transmitter Block Museum.
The Transmitter Block is now a Grade II Listed Building and one of several structures on the former site of RAF Bawdsey that formed the first Operational Radar Station in the world, playing a vital role in the Defence of Great Britain during World War Two. First completed in 1939, the brick-faced Transmitter Block housed Electronic Equipment that sent the Radar Signal out through four 328ft tall Masts, their massive concrete bases are still visible.
The Transmitter Block fell into disuse during the 1970's and steady deterioration led to it being placed on the ‘Buildings at Risk Register’. Freeland Rees Roberts was appointed in March 2014 as Architects for the restoration and, with assistance from the HLF and Historic England, the building has now been completely restored. Inside a new interactive exhibition tracing the history of Radar was opened to the public in September 2017.
Extensive repairs were needed to the surrounding concrete Blast Walls using advanced techniques that will prevent further corrosion of the reinforcement, after careful patching and cleaning, the whole surface was coated with a clear microporous coating that reveals the colour and board-marked finish of the original concrete. This was followed by reinstatement of the Earth Revetments on two sides (the other Blast Walls have been left exposed) the flat concrete roof was completely removed and then replaced with a layer of insulation and a new waterproof membrane. A brick incinerator chimney thought to date from the Cold War Era was in poor condition and rebuilt in matching materials.
A new accessible lavatory block for visitors was prefabricated, clad in Corten steel and lowered into position between two of the Blast Walls, the air source heat pump has a similar enclosure. Internal and external decorations have been carefully matched to the original colours, leaving some of the original finishes and fittings visible. A new exhibition has been installed by PLB telling the fascinating story of Radar in all its detail and the building has now been re-opened to the public
In 2018 the project received a commendation from the RIBA Suffolk Craftsmanship Awards for Restoration and the project also won the 2019 Civic Trust AABC Conservation Award.