The N.Z. Vintage Radio Project

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)

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)

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

Frequency Ranges

Broadcast band:
550-1600kc
Shortwave Bands:
9460-9820kc
11400-12120kc
15060-15520kc
17540-18440kc

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.