Other radios based on the same chassis:
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.
You can see in the rear photo above that this example has been converted to mains operation (as many farm sets were once mains was available). See below for 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)
Several versions noted - 70 (1941), 70P (1941), 70R (1946), 70W (1946) and 70T (1947), . Interestingly, the model 66 (mains version of the same model) also had many revisions. It is likely that the changes were various different tuning gangs (and associated dials), and coil improvements over the life of the model (which seems to have been at least 8 years).
In original fit out from 1941, with V9 vibrator pack and 6V battery leads coiled between that and the chassis. Note the bag wrapping the PM speaker, to keep metal debris out of the speaker coil.
Typically, they are found today, having been converted to mains operation. In this one, the V9 vibrator pack has been removed and a mains transformer and rectifier has been added as indicated by the X. It's probable that the valve line-up has also been changed.
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.
| YEAR | MODEL NAME |
|---|---|
| 1941 | Columbus model 70 |
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