| Local
Battery handset with microphone cut off button in handle. This handset was
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):-
Telephone
No. 28, with press switch.
1 x Connection, Mouthpiece No. 1.
1 x Diaphragm No. 12.
1 x Cord, Instrument No. 4/17A, Brown, 48" (earlier Mouthpiece No. 1 supplies
fitted were 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, Telephone 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, Telephone Suspension, No. 1 added and Cord, Instrument No. 4/15A, 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 Connection, Mouthpiece No. 3 or 4.
1 x Diaphragm No. 23.
1 x Cord, Instrument 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, Instrument No. 403 |
- |
1 |
1 |
- |
1 |
1 |
1 |
| Cord, Instrument 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
(Mark 4). |