While the Courtenay-branded model 15 from mid-1935 was quite widespread and available until at least 1936, it is likely that very few Columbus model 15 sets exist - the NZVRS-member-owned model above featured in the NZVRS Magazine of November of 2003 and was noted as being a rarity. Most likely because the model 15 was a 1935 design and Columbus was introduced in 1937 - by then other 5-valve models such as the 24 and 25 had been released - This makes the existence of a model 15 under the Columbus brandname quite odd - and it might have been produced as an early example of the new brand moreso than a mainstream release.
If you have one, photos and serial number details would be appreciated.
Intermediate Frequency: 465kc/s
Chassis Notes (most schematics can be clicked to download a full size version): The model 15 chassis was Radio Corp NZ's standard AC mains 5-valve broadcast-only receiver chassis for 1935. This is likely one of the first 'unified' chassis models where all brands got the same chassis with just their badge on the back to differentiate them (Previously different brands had their own peculiarities like painted chassis' or different valves and/or circuitry). Known to have been produced for Courtenay, Stella, Pacific and CQ.
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.
|1935||CQ model 15|
|1935||Pacific model 15|
|1935||Courtenay model 15|
|1935||Stella model 15|
|1937||Columbus model 15 - this set|