TELEPHONE No. 121 | ||||||||||||||||||||||||||||||||||||||||||||||
Wooden wall telephone used on CB and Automatic systems. Made from around 1924 and can be found in the 1928 GPO Rate Book. There were two variants, the Mark 234 and the later Mark 2. All models are fitted with a Receiver, Bell No. 1A, but the Mark 234 was fitted with a Transmitter No. 1 and a Coil, Induction No. 14, whilst the Mark 2 was fitted with a Transmitter No. 22 and a Coil, Induction No. 18A. Terminal numbering/lettering and the wire colours also differed - see tables below. Terminal Equivalents
Dial Strip
The dial mount is a Mounting, Dial, Automatic No. 7. The housing is called a Case No. 1 and could be constructed of American Walnut, Black Chuglam, Pyinma, Halou, Tasmanian Myrtle or African Mahogany.
Some were converted by the BPO factories into Telephone No. 251, which are identifiable as they have a handset. Similar to the Telephone No. 101 but with a dial fitted below the transmitter. Because this telephone is sought after by collectors, it is quite difficult to find. A number of reproduction instruments have been seen, generally made up from Bellsets No. 1 or from railway omnibus circuit telephones. Many of these telephones were later converted by the GPO into the Telephone No. 221. The early type used a Transmitter No. 1 which could have Label No. 43 fitted between the speaking tube and the transmitter body. This label advised of the Exchange name and number. See picture above. This telephone superseded the Telephone No. 105. Mark 234 Telephone includes (1928 Rate Book):- Desk No. 4 to be requisitioned separately when required. Mark 2 Telephone includes (1946 and 1956 Rate Books):- To be requisitioned separately when required:- Variations Telephone No. 121 Mark 2 was fitted with the "improved" Coil, Induction No. 18. Telephone No. 121B was supplied with a Dial, Automatic No. 10BA for use in the Brighton Area. Telephone No. 121L was in general use on Automatic exchanges in large exchange areas and fitted with a Dial, Automatic No. 10LA and a Label No. 43C. Telephone No. 121S was supplied with a Dial, Automatic No. 10FS and used on Siemens systems in Grimsby, Hurley, Ramsey, Southampton and Stockport areas (supersedes Telephone No. 77). Telephone No. 121W was supplied with a Dial, Automatic No. 10FW and used on S.T. & C's exchanges at Darlington and Dudley (supersedes Telephone No. 65). Manufactured by: Variants: The Australian Post Office also used the same set - their Telephone No. 137AW which was identical to the Telephone No. 121 Mark 234. Circuit diagram - N221. Circuit diagram - AT 1728. Drawing No's - 8642 & 60490 (Mark 2). Collectors Information - what to look for How to convert a Telephone No. 121 to Plug and Socket Telephone mouthpiece sanitisers See also the Telephone Efficiency Committees Report on Common Battery Area telephones.
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Last revised: January 31, 2023FM |