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ZC1 Mk-2

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ZC1 Mk-2
Circuit diagram
Internal views
Remote Control Units
Installation Type
Truck      Photo
Ground    Photo
Special Committee
Packing Slip
RJ Orbell
Radio Corporation
Radio Ltd

Production ZC1 Mk-2



The Mk II was a development of the Mk-I and its design is generally attributed to RJ Orbell of Radio Ltd.  The significant differences between the two are as follows.

  • The Mk II is dual band having an LF band of 2 - 4 MHz and an HF band of 4 - 8 MHz.

  • A synchronous vibrator was used dispensing with the need for the two 6X5 rectifiers.  (6X5 rectifiers were almost unprocurable)

  • The switchable HT voltage feature was dispensed with.

Other improvements were the tropicalisation of components and improved sealing and weatherproofing of the case, repositioning of the antenna matching controls and meter, replacement of battery terminals with plug and socket, relocating the lamp socket to a more central position and other minor changes often dictated by the availability of specific parts at a given time.  The use of special flux solder as part of the tropicalisation process initially caused many assembly line problems with it's much higher melting point.  One complete batch of 50 sets is reputed to have been rejected and returned to the manufacturer by military inspectors because of dry joints and generally poor soldering when the new solder was first introduced.


Official records show that the Mk-II was originally planned to have a UHF transceiver included in the design matching the No. 19 set. The UHF section was to be an associated stand alone unit with it's own power supply. This idea was not followed up, although prototype UHF modules for this project were designed and constructed as a joint effort between Collier and Beale and the NZ Post Office Radio Section.

Key components such as meters, valves and the main tuning capacitors were all of Australian, American or English manufacture.

Wellington based Radio Corporation was given contracts for the production of the ZC1 Mk II as was Radio Ltd of Auckland.

In all, it is now believed that a little over 9,500 ZC1 Mk II sets were made.

War Service

A number of ZC1 Mk-2 sets were issued for use on the "Home Front" inside New Zealand in the last months of the War. This is the only recorded service seen by the ZC1 Mk-2 in WW2.

ZC1 Mk-2 with canvas cover down


Top                                                                                      April 2009