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.
|1942||Columbus model 90|
|1942||Courtenay model 90 - this set|