telephone instrument, or automatically by the unit (by its
inbuilt ringing detector). All external circuits are opto-
isolated and appear on a varicon fixed plug on the rear
unit. Power requirements 50 V, approx. 560 mA. At 24 V,
approx. 360 mA. At 12 V, approx. 250 mA. Non-BBC
Telephone Interface Unit. To interface between new style
P.O. telephones and EMX control lines. On-board ringing
detector for a.c. or d.c., 4 c/o cradle lift contacts and
facility to put ringing on the line when used with a phone
with a recall button. Can be used on its own or with a
24 V. SCPD 1985.
Control Line Telephone Unit. Provides 17 Hz ringer, ring
detector and hybrip circuit for telephone communication
over Control-Line circuits. Supplied complete with handset
and ring button. Housed in base of Ackermann telephone
handset unit type 10191 and uses Ackermann handset type
20050NI, components are mounted on pcb and connection is by
means of screw terminals. Power requirements 12 V dc, max
lA. Handset base approx. 200 mm x 65 mm x 105 mm high.
Line Holding Transformer Unit. Transformer providing
correc t d. c. condi tions to hold PO telephone line when
diverted from telephone instrument. BBC equipment
(Telephone Balance Units etc.) may be connected to other
winding. Diecast box 17lmm x l20mm x 106mm. SCPD 1976.
Commentators communication phantom unit provides 3 sets of
transformer send circuits for commentators feeds of
programme sound, production talk back and auxiliary input
and cue circuit detectors. Power Requirements: 24V D.C.
ISEP 70 3U high x l78mm P.C.B. with 45mm wide front panel.
Mains Isolating Transformer Unit. Replacement for TU/4
Transformer Unit. Input 240V. Output 240V to BC 1363
socket. Output l15V to Americal 3 pin socket. Total
loading 250Va. Built into plastic case: fuse fitted in
mains input with changeover switch to select either outlet.
Earth pin of outlets not connected, but earth terminal
fitted. Commercial unit to BBC requirements. Radio O&M
Transformer Mounting Printed Circuit Board. Printed
circui t board for mounting 12 LL88 (A-size) transformers.
First used in conjunction with AM7/19 (Short Line Driver
Amplifiers) for the mounting of the associated output
transformers. CH1/76 (printed circuit board is BMM 4U).
Transformer and Gain Adjust Unit. For use in Network
Supervision Mixer, London. The card mounts the input
transformers and gain adjustment controls for the