COLUMBUS 12A (CIRCA 1945)

The Columbus 12A was manufactured for Columbus Radio Centre Ltd by Radio Corporation of New Zealand Ltd in about 1945.

Other radios based on the same chassis:

The updated tiny broadcast-only Columbus Model 12A

The model 12 was released during the war as a budget mantle set, and continued to be produced for a short time once peacetime production started again in 1945.  The differences are not great, likely just changes made to accommodate shortages (including a different tuning gang, and a different dial layout to suit).

Technical Information

Valves (5): 6K8G, 6K7G, 6B8G, 6K6G, 84

Intermediate Frequency: 455kc/s

Frequency Bands: 1

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

A small 5-valve mantle-sized chassis used in Columbus and Courtenay sets - designed for AC or DC (transformerless) operation (with modifications). Notable for having a very shallow chassis necessitating a riser spot-welded to the back in order to mount the serial plate

RCNZ Model 12 Service Info

1940 Courtenay model 12 Schematic

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).

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).

Other documented models using this chassis (3 in total)

YEARMODEL NAME
1940 Columbus model 12
1940 Courtenay model 12 'Tiki'