The Bell Colt All Transistor was manufactured by Bell Radio-Television Corporation Ltd in about 1961. It's part of the Bell Colt series of radios.

Other radios based on the same chassis:

This reasonably scarce transistor radio is the only portable Bell Colt style set. It used a 9V battery mounted directly (albeit upside down) on the chassis, while every other known model was designed for 230V AC.  The old-style large brick 9V battery was held onto the connector using elastic straps that ran through holes in the chassis.

Some had a push-to-light arrangement on the tuning shaft for the dial lamp to help conserve battery life although the photographed model has no dial light at all so this was possibly either a later modification, an early but unreliable mod or perhaps there were two versions.

Interestingly the Columbus Radio Centre advert suggests it was made especially for them, which is possible given Radio Corp and the Columbus brand were wound up by Pye the year previous, and Columbus Radio Centres were now owned by Robert Francis Ltd, a music store chain based in Christchurch.

An interesting ommission in the cabinets - blue is not advertised as an available colour. Also note the push-on plastic knobs appear to have metal inserts in the advert.

The schematic shown below is for the Transette, a model with a very similar looking chassis

The Bell Colt All Transistor 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:

Technical Information

Valves (7 transistors, 1 diode): Either: OC44, OC45, OC45, OA10, OC70, OC71, OC72, OC72
or: 2N412, 2N410, 2N410, Signal Diode, 2N406, 2N408, 2N408, 2N408
or: 2SA30, 2SA31, 2SA31, ?, 2SB32, 2SB33, 2SB33, 2SB33
Lineups to be confirmed, schematic is not clear

Intermediate Frequency: 475kc/s

Frequency Bands: 1

Chassis Notes(most schematics can be clicked to download a full size version)

1961 Bell 7TW

Other documented models using this chassis (2 in total)

1961 Bell model 7TW 'Transette'