There are two types of Muraphone, the Muraphone and the
Muraphone K. The easiest way to identify them is to check the handset cord
- 3 wires original Muraphone and with 4 wires it is the Muraphone K. The
original Muraphone has the GPO style handset with a spittoon mouthpiece, whilst
the Muraphone K has a modern curved handset.
Conversion of the early Muraphone (wired to diagram KS10267)
The terminal layout of the phone is shown below - the terminals are marked in
the plastic.
Using a standard BT line cord wire the phone as follows:-
-
Remove any link between E and L1.
-
White wire of new line cord to terminal L1.
-
Red wire of new line cord to terminal L2.
-
Green wire of new line cord - spare - insulate.
-
Disconnect red wire on the 2uf capacitor.
-
Connect the blue wire of the new line cord to the red wire and
insulated.
-
Fit a 3.3k ohm resistor between E and L1.
-
Fit a Rectifier Element
No. 205 between MR and R.
-
Check transmission and replace transmitter if bad. Click here for more information.

Diagram KS10267
Conversion of the later Muraphone K (wired to diagram KS10992 Issue C)
The terminals are marked on the terminal block.
Using a standard BT line cord wire the phone as follows:-
- Remove the strap between 11 and 12.
- Connect the 3.3k resistor between 11 and 12.
- White wire of the new line cord to 12.
- Remove the strap between 13 and 14.
- Red wire of the new line cord to 14.
- Blue wire of the new line cord to 4.
- Green wire of the new line cord to 3.
- Fit a Rectifier Element No. 205 between
1 and 9.

Diagram KS10992C
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