The Columbus model 515 was manufactured for Columbus Radio Centre Ltd by Radio Corporation of New Zealand Ltd in 1957.

5-valve broadcast mantle radio, available in 5 colours according to advertising sighted for this model.

Examples have been seen in ivory, grey, blue and burgundy, and recently the mysterious fifth colour has come to light - pink!  Thanks to Jamie MacKenzie who owns the photographed model above - that one would be quite rare... 

Two different dial glasses have been sighted - both with red insulated wire strung across the face of the dial drum and soldered in place at each end as a pointer. The white model with the half-circle dial photographed above has a 1957 date code, while the blue and pinks ones above with the full-circle dials are dated 1958.

Note that the white knobs on the pink set appear to be a white plastic version of the old bakelite knobs used on many earlier Columbus radios, while the white knobs on the white set appear to be a white plastic version of the bakelite knobs used on the model 14 and other sets of that era.  Its almost as if they were going for a retro look.

Note: the blue set in the photographs above has been repaired and modified (by the author for his daughter) and pointer is now yellow (originally red) while cabinet is painted to deal with cracks - the chassis is restored to factory except for the addition of an aux cable for listening from an MP3 player / cellphone.  Far from original, but a tidy example electrically.

This set is similar to the Astor / Columbus 525 and the Astor FEU

The cabinet is an Australian hand-me-down from AWA and was used from around 1946 until around 1950 in various models that all looked fairly similar to this set:

Technical Information

Valves (5): 6BE6, 6BA6, 6AV6, 6AQ5, 6X4

Intermediate Frequency: 455kc/s

Frequency Bands: 1

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

NB: Some sets are IF-peaked at 465kc/s as per note below

1957 Columbus model 515 Schematic

1957 Columbus model 515 IF Peak Notes

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.