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Letter from Bruce T. Neale, Marconi Radar Systems Ltd., to Martin Shough 10 Nov 1986

Marconi Radar Systems Limited
Writtle Road
Chelmsford CM1 3BN
Telephone: 0245 267111 Telex: 99108 Facsimile: 0245 357927

10th November 1986

Dear Mr. Shough,

Apologies for delay in responding to your letter dated 31.10.86. I was hoping to send the handbook as promised, but unfortunately have run into a snag. M.O.D. have refused to give their OK on the grounds that the A.P. is still classified! (Restricted) If you have any friends who have connections with M.O.D. Security, the A.P. number is 115H-1300/1400-1 entitled Radar Type:13 (Mk.6 and 7) and 14 (Mk.7, 8, 9 and 10).

However, to help with your research, I have summarized the parameters of the Type 13 and 14 as follows:-

1. Type 13 (Height finder) Mk 7

Frequency: 'S' Band (IOcms).
P.R.F; 250 or S~Op.p.s (depending on role)
Vertical Beamwidth; approx 1(parabolic)
Horizontal Beamwidth; approx 4
'Nod' Angle; 21
'Nod' Rate; 6 nods per min (?)
Antenna dimensions; 20 ft by 5ft 6ins. fed by slotted waveguide
Transmitter Peak Power ;approx 500KW (Magnetron)
Pulse length; 1.9 microseconds

The antenna is 'azicated' onto target by the operator who controls the bearing by means of a servo mechanism from the P.P.I. Console.

The height range console is usually calibrated 100 to 150 miles but its detection range will obviously depend on the radar cross-section of the target.

2. Type 14 (Surveillance) Mk 7 and 9.

Frequency: S .Band
P.R.F.; 250 or 5~0pps (usually 250pps)
Horizontal Beamwidth; approx 1 (parabolic)
Rotation Rate: 0 - 6RPM (normally operates at 6RPM)
Peak Power and Pulse Length as for Type:14 [sic. "14" should read "13"] (Note: The cabins are identical with the Type 13 Mk.7)
The range performance depends on target cross-section, but the P.P.I, is usually set up to 150 miles.

3. Type 14 (Surveillance) Mk 8

As for Mark 7 and 9 but antenna profile shaped to give a Cosec2 cover diagram (Fan beam) for high cover.

4. Type 7 (Surveillance)

Frequency; 200 MHz (metric)
P.R.F.; 250p.p.s
Peak Power; approx 500KW
Pulse length; 3.8 microseconds
Antenna Rotation Rate; 0 - 6 RPM (usually 6)
Antenna Type; 8 bays of stacked full-wave horizontal dipoles, switched for height finding, to compare signal amplitudes from the vertical lobe structure due to ground reflections. (It was in fact a '3D' System!).

Description of typical G.C.1. ("Happidrome") Station

The 'master' radar was the Type:7.. A Type 14 Mk.7 and a Type 14 Mk.8 were synchronised in turning by a servo system at a rate of 6 RPM. The Type 14 Mk.7 with the parabolic beam shape 'looked' in the same direction as the Type:7, and the Mk.8, with the Cosec2 beam 'looked' 180 off beam (ie. the reciprocal bearing). No distinction was made as to which radar was used for interception, all radar data was fed to the various consoles and was selectable, the choices were: Type:7 only, Type:14-Mk.7, Type:14-Mk.8, Type:7 plus Type:14-Mk.8 (automatically switched over a selectable sector of 180). In general, the Type:7 was the main radar, the Type:14-Mk.7 was a 'low-cover' gapfiller and the Type:14-Mk.8 was for high cover. The controller/operator made the best use of the available data to suit a specific situation.

Two Type:13's were used to supplement the height finding of the Type:7. The Type:13 was 'laid-on' (azicated) by the operator by bisecting the target on the PPI by an 'intertrace' marker and the height read from an adjacent height-range console.

I have sketched a rough layout to the best of my recall and enclosed photographs of a Type:14 and Type:13.

I hope this brief data will suffice. Should you have any further questions, please call me on Chelmsford (0245) 26711 either on Tuesdays or Thursdays.

Yours sincerely,

Consultant ~
Marconi Radar Systems Limited

Enc: Photographs