Ultra Twin R656

• alternative name: Ultra Radio and Television

Uses an S.T.C DRM 2B as rectifier.
Rear panel has an external aerial socket.

A lever on a spring loaded slide switch locks the radio in the "battery" mode when the mains plug is parked in a holder. This was to suit a UK 5A two pin and some smaller 5A 3 pin prior to the 3 rectangular pin system adopted in the late 1950s. The chassis is also connected directly to one wire of the mains cable when in "mains" mode (default) and power switch on. Today the set is best operated via an external isolation transformer or on batteries.
There is an external aerial socket isolated by a Silver Mica capacitor.

This Twin uses separate batteries (Presume B129 and AD39 as claimed by trader 963 for Twin 50). A  B126 + AD38 will physically connect, but B126 is 90V and the label clearly states 85V. A B129 and AD39 fit snugly.

If the radio has one battery plug, then it's the Twin 50 R568 or some other Twin as  R&TS states this uses a combined battery. Presumed to be B127 (size & rating and claimed by Trader 963).

In questo link sono elencati 235 modelli, di cui 153 con immagini e 149 con schemi.
Elenco delle radio e altri apparecchi della Ultra Electric Ltd.; London