6-valve portable battery and mains radio with economy mode.
Notes on service info shows that, from testing 2 hours per day in full mode and 2 hours per day in reactivation twice per day this set will do 80 hours on fresh batteries in full mode, 130 hours in economy mode and 200 hours in battery reactivation mode (a form of simple trickle charging)The Columbus model 653 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:
1941 Columbus model 201 Portable
1947 Columbus model 301 Portable
1947 Columbus model 402 Portable
circa 1948 Columbus 402Z Portable
circa 1948 Columbus 402X
1952 Columbus model 502 Portable
1955 Columbus model 653 Portable
1959 Columbus PZ117 Transistor Seven
1959 Columbus 694P Transistor 6
Intermediate Frequency: 455kc/s
Frequency Bands: 1
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.
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).