The Bell Colt Original was manufactured by Bell Radio-Television Corporation Ltd in 1951, production ran for about 3 years.
This model is part of the Bell Colt series of radios.

The original Bell 'Colt'.  Believed to be identifiable by having 5 rimlock valves and no chassis model marking - the next known model, the 5B4, does have its model code stamped on the chassis (most, but not all).  This set was one of the first to carry the Bell name, and the first in a line of Colts that would span almost 30 years and sell in the 10's of thousands.

The Bell Colt Original is part of the Bell Colt series of radios.

Bell Colts ran from 1951 through until 1980 - the longest running model of NZ built domestic radio.  It saw many different engineering changes over the years, and the last few models dropped valves in favour of new transistor technology.  There is considerable information on the main Colt page about this Kiwi icon.

The radios in this series are:
1951 Bell Colt Original
1954 Bell Colt 5B4
1955 Bell Colt 5B5
1957 Bell Explorer Colt
1957 Bell Planet Colt
circa 1957 Bell Colt 3B7 Champ Colt
circa 1957 Bell Colt Cadet
circa 1961 Bell Colt All Transistor
1967 Bell Colt 5B67
circa 1968 Bell Solid State Colt
circa 1975 Bell Solid State Colt Mk III

Valves (5): ECH41, EF41, EBC41, EL41, EZ40

Intermediate Frequency: 462kc/s

Frequency Bands: 1

Chassis Notes(most schematics can be clicked to download a full size version) David Clist noted an issue with the tone control circuit producing high harmonic distortion at the full bass position - although as most people never set the tone control here its unlikely anyone would have ever noticed. RJ Hatton notes in his 3-part series on the Colt (October 2004) that 100pF caps in this model could prove to be unreliable and cause a crackling sound (possibly a form of silver mica disease). I.F. transformers are ETA round-cans. These were on early 5B4 models as well.

All documented models using this chassis (3 in total)

1953Skymaster Colt
1953Rolax Colt
1951Bell Colt Original - this set