Radar, AA, No4 Mk6,old MZPI Antenna

Radar, AA, No4 Mk6, old MZPI Antenna

Radar, AA, No4 Mk6,new MZPI Antenna

Radar, AA, No4 Mk6, new MZPI Antenna


To provide early warning or putting-on data to fire control equipments Radar, AA, No3, Mks1,2 and 7.


An initial order for 150 was placed but no deliveries were made by the end of the war. Canadian manufacture and was the mainstay of British Army radar for many years after the war


Mobile medium range microwave radar unit in a four wheeled trailer. the aerial folds flat on the roof for travelleing. The putting-on facility can be increased by the incorporation of a British pattern adjacent display unit which feeds data to a remote gunsight.

Presentation Unit

Plan position indicator (PPI) of targets on 9" CRT to optional ranges of 40,000yds, 80,000yds and 120,000yds.
'A' type scan on a 5" CRT for monitoring.
Adjacent display (AD) plan position indication of targets on a remote consol.

Antenna System

Continuously rotating array consisting of two stacks of slotted waveguide radiators arranged and fed to permit selection of one of three beams either manually or in an automatic sequence. Waveguide feed with a common T and R system using soft rhumbatron. The aerial array is motor driven at 15rpm or 18rpm dependant upon power supply frequency

Physical data
Weight19,000 lbs approx
Heightoperational 13'10.5"
 travelling 11'5"
Lengthoperational 17'2.5"
 travelling 21'8"
Widthoperational 8'9"
 travelling 8'9"
Turning circle60'0" inc tow veh'
Ground clearance16"
Wading depth5' still water
 5' + 1'6" wave
Bridge class9
Tyre size7.50-20 / 34x7
Tyre pressures65 psi front,75 rear
Braking systemWarner electric with handbrake
Towing vehicleHAA tractor
Electrical data
Operational wavelength2,850Mc/s
I.F. freq30Mc/s
Receiver bandwidth3Mc/s at -6dB
Tx power output600kW
Tx pulse width1 us
Recurrence freq660 c/s
Detection accuracyrange +/- 1000yds
 azimuth +/- 2deg
 elevation 5,000' at 40,000yds
Detection range120,000yds
Target discrimination range500yds on 40,000yd sweep
Target discrimination azimuth5deg
Data Transmission Range & azimuthby magslips
Data Transmission Elevationby telephone

Power Supplies

230V ac 50-60c/s, single phase.
Consumption : 10 kVA
Normally supplied by a skid mounted caterpillar diesel (D311)
60c/s - 22.2 kVA - 20 kW - 0.9 PF
50c/s - 16.6 kVA - 15 kW - 0.9 PF


Radar : 2
Plotting : 1
AD : 1


Interference suppressor is incorporated in the receiving system which discriminates between unwanted and wanted signals on the basis of amplitude.


Provision is made for the fitting of IFF when provided.

Special Features

The set is of tropicalized construction throughout. An air dryer is fitted into the waveguide system. To minimize ground clutter provision is made to tilt the aerial array by means of wedges.


No4 Mk6/1

Old MZPI antenna system.Early versions seem to be have built on the shorter No4 Mk1 style trailer.

No4 Mk6/2

New MZPI antenna system.

References and Sources

More No4 Mk6 pictures

Radar AA, No4 Mk6

No4 Mk6 radar

Surviving No4 Mk6 radar picture 1

A surviving No4 Mk6 radar somewhere in the UK

Surviving No4 Mk6 radar picture 2

A surviving No4 Mk6 radar somewhere in the UK

Surviving No4 Mk6 radar picture 3

An internal photo of the No4 Mk6 radar