COLUMBUS MODEL 70 (1948)

The Columbus model 70 was manufactured for Columbus Radio Centre Ltd by Radio Corporation of New Zealand Ltd in 1948.

6-volt (vibrator supply) powered dual wave radio.  Battery version of the model 66.

These types of sets are often referred to as 'Farm Radios' as (in New Zealand, at least) many rural areas had no connection to the national grid (such as it was) until the 50's or even later - this meant that people in these areas relied on batteries and/or their own power generation.

Photo is actually a model 66, however the differences were only in the chassis, the big giveaway for any battery model from the Radio Corp NZ stable is the red badge on the back. 

See the Courtenay model 70 for further chassis details.

Valves (6): 1K5, 1C7, 1K5, 1K7, 1K5, 1J6

Intermediate Frequency: 455kc/s

Frequency Bands: 2

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

Two versions - 70 (and 70T?  A note on the schematic suggests the 70T was never seen in production) - and the 70R and 70W which is held as an early engineering drawing from the RCNZ Lab.

1948 Courtenay model 70

1948 Courtenay model 70

 

It can be seen that this model has been converted from battery to mains operation.  The V9 vibrator pack has been removed (it would have normally sat in front of the speaker as indicated - the mounting holes can still be seen) and a mains transformer and rectifier has been added as indicated by the X.  Its probable that the valve lineup has also been changed.

1948 Courtenay model 70 modified

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).

All documented models using this chassis (2 in total)

YEARMODEL NAME
1948Courtenay model 70
1948Columbus model 70 - this set