How To: New Wire-5 project (Bergeron)

[Chris Suslowicz]

Originally Posted by Robert Bergeron

Built a homemade Tannoy speaker today to listen to the WS No 19 set . Still looking for an amplifier to connect to one of the drop plugs but the search is narrowing .

Looks good. Does the Tannoy speaker have a transformer attached to it?

There's a discussion of the Sexton SPG setup with Control Unit 190 that uses the WS19 IC amplifier to drive the loudspeaker. (This is not what you want, as it will be much too loud, being intended for 25 pdr gun crew instructions in a confined space, and the gun crew did not use headsets.)

It may provide a few pointers on how to do it, though.

(I recently bought a Canadian ALS No.2 Mk.2 loudspeaker (with added woodworm) that has the lower pair of terminals for the WS19 IC amplifier drive. That uses the 30 ohm tapping on the transformer (the ALS uses a higher impedance drive - I think what was known as "100 volt line" - to allow the use of field cable without excessive losses), and the loudspeaker switch selects 'A' 'Off" and 'B' on the Control Unit 190, with a resistance in series to prevent overloading the amplifier. (I intend to draw out the circuit diagram from the photographs in that thread, and match it with the parts list from EMER Tels FZ-256/3 in order to (a) see how it is supposed to work, and (b) construct something vaguely similar.)

The Sexton appears to be fitted with Control Unit No.2 for the Wireless Op,
No.190 for Commander (droplead) and gun crew (loudspeaker), plus a Junction Distribution No.3 for the driver intercom - though I need to check that.

On the move only the commander, wireless operator and driver would have headsets (intercom and wireless), maybe with the loudspeaker on when required. Deployed they could use wireless or lay wire and use the ALS for the GPO and four guns. (I think - I'm not an artillery person.)

Best regards,
Chris.