COLUMBUS 402Z 'PORTABLE' (CIRCA 1948)

The Columbus 402Z was manufactured for Columbus Radio Centre Ltd by Radio Corporation of New Zealand Ltd in about 1948. It's part of the Columbus Portables series of radios.

Other radios based on the same chassis:

Same as the model 402, only with miniature valves.  5-valve + selenium rectifier.  Internal loop aerial. 

Note: The model 402A is probably more similar to this model than the base model 402.

1948 Columbus 402Z

The Columbus 402Z is part of the Columbus Portables series of radios.

This series contains all the known Columbus portable radios - including a few transistor portables from the final few years of the brand.

The radios in this series are:

Technical Information

Valves (6 (or 5)):
1N5, 1A7, 1N5, 1H5, 1A5, 1A5
1N5, 1A7, 1N5, 1H5, 3Q5 (s/n 84401 onwards)
1T4, 1R5, 1T4, 1S5, 3S4 (model 402A)
1T4, 1R5, 1T4, 1S5, 3V4 (model 402Z)

Intermediate Frequency: 455kc/s

Frequency Bands: 1

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

At least three variations on the base schematic - from serial number 84401 the original twin-parallel 1A5's are replaced with a 3Q5.  And the 402Z appears to be an almost complete redesign around miniature valves.

 

1948 Columbus model 402 Schematic

1947 Columbus model 402A Schematic

1948 Columbus model 402Z Schematic

1947 Columbus model 402A

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 (4 in total)

YEARMODEL NAME
1947 Columbus model 402 'Portable'
1948 Columbus 402X 'Portable'
1947 HMV 476P 'Devon'