The Courtenay model 75 was manufactured for Turnbull & Jones Ltd by Radio Corporation of New Zealand Ltd in 1940.

Other radios based on the same chassis:

Courtenay version of the Model 75 bandspread receiver - and the first bandspread radio designed and manufactured in New Zealand (and almost the first in the world).  The model 75 is a 6-valve + magic eye set.

There is considerably more information on the model 75 under the Columbus version, which is virtually identical except for the cabinet design and dial glass branding.

Courtenay model 75 'Super Defiant'
Turnbull & Jones Radio Merchandiser Magazine 1940

1940 Courtenay model 75

Technical Information

Valves (6 + eye):
first version: (DWG 326)
6K7G, 6K8G, 6K7G, 6B8G, 6F6G, 5Z4G and 6U5 Magic Eye
amended first version: (DWG326 amended)
KTW61, X65, 6K7G, 6B8G, 6F6G, U50 and Y63 Magic Eye
second version: (DWG 347)
KTW61, X65, 6B8G, 6J7, 6F6G, U50 and Y63 Magic Eye

Intermediate Frequency: 455kc/s

Frequency Bands: 5

Chassis Notes(most schematics can be clicked to download a full size version)

 First release of technical information Columbus_model_75_Service_Supplement_S40-1_24th_May_1940.pdf

First Schematic (developed 1939, drawn 20th May 1940, released 24th May 1940 in Service Supplement S40/2)

Columbus model 75


Amended first schematic using Osram valves (Changes came into effect 1st August 1940, amended schematic drawn 5th September 1940, released in the full service booklet)

1940 Courtenay and Columbus model 75 Schematic


Third schematic (Drawn 16th June 1941, released 1st July 1941)

1940 Courtenay and Columbus model 75 Schematic Supplement

Columbus model 75

Frequency Ranges

Broadcast band:
Shortwave Bands:

General Construction Notes for Radio Corporation of New Zealand Ltd:

The first digit of the serial number typically indicates the year of manufacture of RCNZ chassis' (although not the decade - that requires a little knowledge of the valves, construction, etc). Sets from around 1934 onwards were often (but not always) constructed in a distinctive pressed 'baking pan' style chassis, seemingly unique to RCNZ.

Model codes beginning with a 0, for example the model 051, are Osram valve versions of the model without the leading 0. Technically the 0 should be an O (for Osram), however the digit 0 was used throughout the site before this fact was discovered.

The E suffix indicates a magic eye option is fitted (in models which were available with or without, such as the model 25).

A and B suffixes appear to be simply updates to the current model, R also appears to be simply an updated model ('R'edesign, perhaps?)

P indicates either a permanent magnet speaker version of a model which also came with an electromagnet speaker (the model 26 for example), or a portable model (like the model 694P).  This suffix was used in the mid 50's when Radio Corp was changing over.

N and M indicated miniature valve versions of a model which started with all (or a mix, ie: model 5) of larger valves. One of these two codes may indicate a transitional mixture of octal and miniature - clarification is required.

S often indicates a stereo model.  It can also indicate 'self-biased' in the transition period between back-biased and self biased sets where there were models with both methods employed (53S for example)

Finally, other suffixes and prefixes make occasional appearances in the RCNZ lineup - like the 66W (a variant of the long-running model 66) and the 75XA (a 10-valve version of the model 75 with a separate amplifier chassis).

Model nicknames are often sourced from either newspaper advertising, company literature or the NZ Radio Traders Federation official trade-in price books (Particularly Courtenay models from this publication)

In 1954, model numbering changed, to begin with the number of valves (ie: 501 - 5 valves, 1006 - 10 valves, etc) although the final 2 digits don't appear to have much significance.  Middle digits of 5 (portable) or 6 (mantle, including clock radio) are used on the AWA-designed plastic-cased sets.

Other documented models using this chassis (2 in total)

1940 Columbus model 75