4-valve broadcast band radio for DC mains
Up until the 1940's some areas of Auckland had DC mains power, and AC mains radios would not work on this system. Many brands had models available for this market, including Skyscraper. DC mains radios did not need a rectifier valve, since those are used to turn AC into the DC voltages required by the circuitry - making this 4-valve set equivalent to its 5-valve AC mains sister model
Frequency Bands: 1
Chassis Notes(most schematics can be clicked to download a full size version)
Circuit very similar to Courtenay model 5DC (4-valve broadcast-only DC).
Service information (RCNZ_-_model_5DC_Courtenay_-_4V_BC_DC_-_1934.pdf) here
General Construction Notes for Radio (1936) Ltd:
Early Radio Ltd. schematics did not show the models, just the year, valves and bands, so some sleuthing is required to find the right one.
Early 30's Ultimate models with three digit model numbers indicated both the number of valves in the set, and the price it retailed for - for example, the model 856 was an 8-valve radio which retailed for $56 pounds. The equivalent Courier models were reversed, so an Ultimate 856 was a Courier 568 (theoretically, at least). This was the Auckland price though, and often the sets would retail for 1 or 2 pounds more in other centres, presumably to cover the freight cost of moving them around the country from the Auckland factory.
Note the use of old resistance terminology on older schematics: ω means ohms and Ω means megohms.
Some 1936-onward 3-letter chassis codes vary the last letter between brands, for example:
BBU - Ultimate model BB
BBR - Rolls (and Golden Knight) model BB
BBC - Courier model BB
All use the same chassis.
Golden Knight, Courier and Rolls appear to use the same copper-painted chassis while Ultimate chassis' are painted silver
After the war a new model code system was introduced, whereby radio models all began with R - the first model being the RA, a dual-wave 5-valve set commonly released in a pressed tin cabinet.