TELEPHONE No. 28


Handset with microphone cut off button in handle.

Used on many early telephones.

See also:-
Telephone Efficiency Committees Report on Local Battery Area telephones.

Telephone No. 28A was used at Brighton and Glasgow only and had no cut off switch.

Telephone included (1946):-
No. 28, with press switch.
1 x Conn., Mouthpiece, No. 1.
1 x Diaphragm No. 12.
1 x Cord, Inst., No. 4/17A, Brown, 48" (earlier 1 Mouthpiece No. 1 supplies fitted with No. 4/03A, Brown, 48").
1 x Earpiece No. 14.
1 x Receiver, 150 ohm.
1 x Transmitter, Inset, No.3

No. 28, with Loop Loop, Tele. Suspension, No. 1 or No. 2 added. (No. 2 added for Mark 237 only) (1928 and 1946).
Used with:-
Suspender, Microtelephone, No.2.
Hook, Receiver, E, or No. 12.

No. 28, with Loop and Cord 4/15A, Brown, 48" (1928 and 1946)
Used with:-
Loop, Tele. Suspension, No. 1 added and Cord, Inst., No. 4/I5A, Brown, 48" substituted for No. 4/03A, Brown.
To be requisitioned separately - Plug No. 401.

No. 28A, without press switch - for Brighton and Glasgow only (1928).
1 x Conn., Mouthpiece, No. 3 or 4.
1 x Diaphragm No. 23.
1 x Cord, Inst., No. 421 modified.
1 x Earpiece No. 12.

No. 28, with press switch (1928)
Refer to table below:-

Item Mark Number
234 235 236 237 NT2 NT3 NT
Connection, Mouthpiece, No. 1 1 1 1 1 1 1 1
Cord, Inst., No. 403 - 1 1 - 1 1 1
Cord, Inst., No. 417 1 - - 1 - - -
Diaphragm No. 12 1 1 1 1 - - -
Diaphragm No. 18 - - - - 1 1 -
Earpiece No. 2 1 1 1 1 - - -
Earpiece No. 8 or 9 - - - - 1 1 -
Earpiece No. 13 - - - - - - 1
Earpiece No. 14 - - - 1 - - -
Mouthpiece, No. 1 1 1 1 1 1 1 1
Receiver (ohms) 150 150 150 150 120 120 150
Ring, Receiver Adjusting NT 1 - - - - 1 1 -
Transmitter No. 10 - 1 1 - 1 1 -
Transmitter, Inset, No. 3 1 - - 1 - - -

Circuit diagram - N128.
Drawing  - 8241 & 82491.

 

 
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Last revised: April 02, 2020

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