The model 90 was Radio Corporation of NZ's replacement bandspread model for the 75. It was a 6 valve + magic eye set with 5 bands.
For detailed information, see the Columbus model 90 page. Columbus and Courtenay model 90's were practically identical aside from the brand name on the dial.
Intermediate Frequency: 455kc/s
Frequency Bands: 5
Chassis Notes(most schematics can be clicked to download a full size version)
1. Broadcast (550 - 1600kc/s)
2. Shortwave (6 - 18mc/s)
3. Shortwave (14.85 - 15.73mc/s)
4. Shortwave (11.65 - 12.2mc/s)
5. Shortwave (9.45 - 9.75mc/s)
Note: the capacitors used in the tone cct are oil-filled and are often found to be leaky after all these years, making a mess under the chassis. They are soldered into cups in the chassis and can be removed reasonably easily.
Volume control full on. Tone control position 5. Sensitivity based on x microvolts input to give 50mW standard output.
|1400kc/s||Antenna lead through dummy antenna||2.5|
|1000kc/s||Antenna lead through dummy antenna||3.0|
|600kc/s||Antenna lead through dummy antenna||4.0|
|15Mc/s||Antenna lead through dummy antenna||1.5|
|6Mc/s||Antenna lead through dummy antenna||1.5|
|Bandspread||Antenna lead through dummy antenna||1.5|
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).
|1942||Columbus model 90|
|1942||Courtenay model 90 - this set|