COLUMBUS MODEL 504 'SNOWDON' (1955)

The Columbus model 504 was manufactured for Columbus Radio Centre Ltd by Radio Corporation of New Zealand Ltd in 1955.

5-valve mantle radio

1955 Columbus model 504

The cabinet used for this model also appeared in several different kitsets in English radio magazines, and was probably of English origin.

1955 Bridisco Crystal SetInterestingly, around the same year that this model was released an English company (The British Distribution Company, or Bridisco) released a crystal set with a remarkably similar design, seen here 

Technical Information

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

Intermediate Frequency: 455kc/s most likely

Frequency Bands: 1

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

1955 Columbus model 504 Schematic

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).