COLUMBUS MODEL 69 (1941)

The Columbus model 69 was manufactured for Columbus Radio Centre Ltd by Radio Corporation of New Zealand Ltd in 1941, it was in production for about 1 year.

1941, 3-band (bandspread) 6-valve radio

The model 69 was clearly designed to fit somewhere between the dual-wave model 66 (which sold for years and in great numbers) and the mighty model 75 bandspread, however it is unlikely these sold in great numbers given how few appear for sale these days, nor do they appear in any period advertising found so far (although the Courtenay version was advertised briefly). 

The circuitry and the chassis layout looks very similar to the model 66, and the schematics were drawn in the same month - so it's likely the two models were designed together - and while the model 66 sold right through the war and out the other side in many different cabinet designs and configurations, the model 69 only seems to appear in one cabinet, in low numbers and all sighted serial numbers (to date) are 1941 dated.

Technical Information

Valves (6): 6K7G, 6J8G, 6B8G, 6J7G, 6F6G, and U50 or 5Y3G Rectifier

Intermediate Frequency: 455kc/s

Frequency Bands: 3

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

1941 Columbus model 69

1941 Columbus model 69

1941 Columbus model 69

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.