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| This is an H2S Mk 2A system using the 162 Indicator and the 207 Switching Unit at the right. The Mk 2D used the 184A indicator which differs slightly from the unit above. (Photo by Norman Groom, Pitstone Museum , UK. Used with permission) |
There are two CRT's in the H2S Mk2D indicator. The larger of the two provides a PPI display of the surface below the aircraft, while the smaller CRT permits the operator to determine the altitude of the aircraft. From the interpretation of the PPI display, the operator is able to determine the range and bearing of identified objects, fix the position of the aircraft and home on to targets for blind bombing. When the appropriate adjustments have been made, the ground speed of the aircraft can easily be determined from the main H2S display. The system requires power inputs of approximately 720 VA and 100 watts from AC and DC sources respectively.H2S Mk2D consists of the following units: transmitter-receiver, TR3l9l; modulator type 64; power unit type 280; waveform generator type 34; receiver unit, type 3515; indicator unit, type 184A; scanner type 3;. tuning unit type 207 A; switch unit type 207B; heading control unit type 218; scanner speed control type 477; switch unit type 274 and a filter unit type 173. A scanner heater, AR1-5153AU is installed in the fuselage perspex cupola. Two junction boxes, type 83 and type 222, incorporate the interconnections of the whole system.
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| This is an H2S Mk 2A system using the 162 Indicator and the 207 Switching Unit at the right. The Mk 2D used the 184A indicator which differs slightly from the unit above. (Photo by Norman Groom, Pitstone Museum , UK. Used with permission) |
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| 184A Indicator for Mk2D. Except for the lack of a meter, it is similar to the 162 indicator above. This example has been picked clean of omponents. (Courtesy Aviation Fourm web site) |
In the Mk 2D, the klystron has been moved to another location, hence the disappearance of the tuning meter in top left corner of of the display. Also gone is the mechanical tuning for the klystron.
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| H2S radome as fitted on a Canadian Lancaster. The aft end of the dome is painted white. (From the collection of John Phillips) |
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| H2S as seen on on a RAF Halifax aircraft - with and without radome. (Courtesy UK government via Wikipedia) |
Credits and References:1) H2S Mk IIA Display photo http://website.lineone.net/~norman.groom/h2s.htm
2) H2S antenna with and without radome : http://commons.wikimedia.org/wiki/File:388px-H2S_Radome_And_Scanner_On_Halifax.jpeg
3) John Phillips <johnph(at)xplornet.com>
4) 184A photo . Aviation Fourm web site: http://images.google.com/imgres?imgurl=
http://www.429sqn.ca/bch2s01.jpg&imgrefurl=
http://forum.keypublishing.co.uk/showthread.php%3Ft%3D92454&usg=
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1&um=1&tbnid=dQyNIMzKZzZS0M:&tbnh=97&tbnw=119&prev=
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