I am always getting asked where to get telephone leads and the electronic transmitters from.

So I now produce a kit of parts to convert your old GPO - Post Office - BT telephone and even some privately supplied phones (most UK produced phones can be converted - if you have a diagram).  The kit works on UK wooden, 200, 300 and 700 type instruments (mail me about other types, including foreign phones).  Most GEC, British Ericsson, ATE, ATM and Siemens Brothers phones can also be converted.

Replacement Transmitter
The old carbon granule transmitters on 200, 300 and 700 phones will generally be noisy or no transmission at all.  The best method to fix this is to replace the transmitter with a modern electronic transmitter.

Replacement GPO red and blue electronic transmitters (red will work on 200, 300 and 700 type telephones, whilst the blue variant will only fit in 700 type telephones) are sometimes available.  I can also supply new original carbon granule transmitters and many small parts for Trimphones and 700 types - please email me for price and availability of these.

Modern Line Cords
As from 1st January 2013 there is a choice of two line cords.  Both are PVC and 3 metres in length.  These are a great improvement on previously supplied line cords.

Black round cord, with UK plug on one end, spade terminals at the other and a grommet Light grey oval cord, with UK plug on one end, spade terminals at the other and a grommet

For 200/300 types choose the black cord and for 700 types the light grey cord is more or less the same as the cords used by BT when converting 700 types in the 1980's.  For black coloured 700 types the black cord can also be used.

Ease of installation
I am also asked how easy is the kit to fit.  So far I have only had a couple of failures (these were fixed by Email advice) and most people get it right first time.  But, as I cannot guarantee that your old phone is in good working condition to start with, then I cannot guarantee that your conversion will work.  I will, however, give email support to those people who buy the kit from myself. 

I will also convert a phone on request - please advise of manufacturer and model number.  Remember the carriage costs will be on top of the conversion cost.

Braided Cords
Click here for replacement braided and cloth telephone cords

Tools required
To fit the kit you will need:-

  1. Flat bladed screwdriver.

  2. A small piece of foam to pack out the replacement transmitter (if required).

  3. Long nose pliers.

Conversion Kit Details
The conversion kit consists of:-

  1. One UK plug ended telephone lead (your choice - as described above).
  2. One 3.3K resistor.
  3. One Rectifier Element No. 205 equivalent.
  4. Instructions on how to convert.
  5. Email support.

The above kit does NOT include a transmitter.  The kit includes instructions, but you will also have to refer to the transmitter replacement section for 200 & 300 type telephones (if an electronic transmitter is supplied) and the conversion page for the actual wiring information of your phone.

A fully converted 700 type can be seen here

Kit Prices
Correct as of 14/11/2012 (slight price increase due to postage price hike)
The cost of the conversion kit is 8.50 - which includes post and packaging within the UK.  Please email for a discount price if you order more than one.

At present I have the following spares:-
Red electronic transmitters - 7.60 each or 7.00 if ordered with a conversion kit - out of stock - do not order
Grey 700 type curly handset cords - new - 3.60 each or 3.00 if ordered with a kit.
Grey 700 type handset - hearing amplifier model - new - 10 each if ordered with a kit (these are the GPO Handset No. 17A and also have a neon lamp in the handset - the neon lamp will generally not work on the UK socket system).

Please send a cheque made payable to 'British Telephones' at the address below:-
Crown lane
GL15 4TP

Kits may take up to three weeks to arrive.

Remember to include a return address and if ordering a kit, the colour of the cord.

If you are a purest, I also have some bell ringers (Bell No. 59D-1 un-mounted) with a coil resistance of 4000 ohms.  These will fit straight into 700 type telephones, but can be modified to fit 300 types.  They will also fit in Bellsets.  Email me if you want one of these.

Please note: The kits I supply are for domestic use only and not for resale.

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Last revised: June 25, 2013