Sales Brochure -
DLE650 TELECOMMUNICATIONS INSTRUCTION
C MARKETING - INSTALLATION
3 INTERNAL
M 4001
Issue 1 (September 1971)
HOUSE TELEPHONE SYSTEM No. 2
Description, Installation and Maintenance
General
This
Instruction describes the House Telephone System No. 2. The telephone instruments are coded
in the 500 series and are similar in appearance to the Telephone No. 706, except that the dial
is replaced by a push-button unit. House telephones of the 100 series (see EI Q3950) cannot
be interconnected with 500 series House Telephones.
Facilities
The House Telephone System No. 2 provides intercommunication between two or more locations
(16 stations maximum) without secrecy. Access to exchange lines cannot be given, and the
whole system must be housed in one premises. Several conversations may be conducted at the
same time and conference calls may be established between an number of stations.
Description
Table and wall instruments are available having 5, 10, and 15 push-buttons, these are
suitable for up to 6, 11 and 16 stations respectively. A multiple cable corrects the
instruments together and the 10v dc required for operating the system is obtained from a
Power-unit No. 53A. The table and wall instruments cannot be converted from one to another.
All table telephones are supplied with line cords but not with terminal blocks.
Wall mounted instruments are not supplied with line cords and should always be cabled
direct. The telephone instruments are fitted with Handsets No. 3 but to ensure operation of
the spring-sets an additional weight (Part 1/DWE/7) is fitted.
The wall variants can have the handset temporarily placed, on the handset
rest, in an "Off Hook" position.

There are two diagrams in the Q series for the system:-
Q361 Shows telephone instrument and wiring of instrument to terminal block.
Q362 Shows cabling of system and explanatory diagram.
Method of operation
Each
calling button has a 'normal press' and an 'overpress' position. After lifting the
handset, the required station calling button is depressed to its full extent. This
operates the buzzer at the called station. When pressure is released the button restores
to the 'normal press' speaking position. At the conclusion of a call, replacing the
handset will release any operated calling buttons.
Conference calls may be established between any number of stations. The initiating caller
must call each required station in turn. The called party must then depress the calling
button appropriate to the initiating station.
Numbering of stations
Stations should normally be numbered in sequence according to their position in the
multiple cable. If, however, the subscriber has any specific station arrangement, stations
may be numbered and wired in any order, but the most economical cable run should be
followed. A directory card is supplied with each instrument, enabling each station to be
associated with a person's name. It should be noted that when installations consist of 6,
11 or 16 stations, the additional station is called by utilising at each station the spare
button corresponding to that particular station number. if the subscriber wishes he may
unclip the calling button cover and remove the numbers provided, replacing them with a
designation label to suit his own requirements.
Installation
Table 1 shows the types of telephone instruments together with the number of stations that
can be accommodated and the cable required. If, at the time of installation, there is the
probability that the system may require extending at some future date, a larger cable
should be fitted initially.
TABLE 1
Maximum Number of Stations
|
Telephone House
No.....
|
Type
|
Wiring Size
|
6
|
500
|
Table
|
21 wire
|
6
|
501
|
Wall
|
21 wire
|
11
|
502
|
Table
|
24 wire
|
11
|
503
|
Wall
|
24 wire
|
16
|
504
|
Table
|
41 wire
|
16
|
505
|
Wall
|
41 wire
|
Siting of telephone instruments
Very damp or dusty situations are unsuitable for House Telephone Systems.
Cabling limits
The maximum cable length between the two extreme stations is 600 yards for 5 and 15 button
instruments. This will be reduced to 300 yards if one or more stations has an extension
caller fitted. The 10 button instrument is limited to a maximum cable length of 500 yards,
or 200 yards if extension callers are used. This can be increased to 600 yards 300 yards
respectively, by running an additional 2-wire cable connected in parallel with the power
pair in the main cable.
Extension callers
In addition to the buzzer in the instrument either a Bell No. 56A or Buzzer No. 20B can be
fitted as an extension caller, the choice being left to the subscriber. In each case the
coils should be connected in series.
Maintenance
The following individual items are replaceable:-
Transmitter-inset No. 13C or No. 16.
Receiver-inset No 4T.
Handset No. 3.
Weight, Part I/DWE/7.
Cord, Instrument No. 1. 4/88AK, ..., 10 in.
Should any other components require replacement, then the entire instrument must be
replaced.
Power supplies
The House Telephone System No. 2 is designed to operate from a 10v dc supply derived from
a Power Unit No. 53A. If possible, the power unit should be located near the centre of the
system rather than at one end, and should be connected to the system as shown on Diagram Q362.
Introduced circa 1967.
TELECOMMUNICATIONS INSTRUCTION
B MARKETING - COMMERCIAL
4 Facilities & Apparatus
N0004
Issue 1 (December 1970)
HOUSE TELEPHONE SYSTEM No. 2
Facilities
This system is available in three sizes of 6, 11 or 16 station maximum capacity. It
should be used for all new installations. Table or wall instruments are available-in
two
tone grey only. They are similar to the 700 type table telephone except that the
dial has been replaced by a 5, 10 or 15 way press button unit. The extensible
handset cord is coiled and the table instrument is supplied with a 1.8m
(6 ft) cord. Longer cords are not
available. The wall telephone is cabled direct.
A label identifying the station is associated with the
press button unit, and a directory card is supplied with- each
telephone. The normal calling signal is a buzzer contained in the telephone
case, but an extension bell or buzzer may be provided at any station subject
to agreement by the Engineering Division.
Each button has three positions, viz; normal, speak and
call. Full depression of the button operates the buzzer in the telephone at
the called station (if the called station is engaged, conversation will be
heard).
Release at pressure allows the button to move to the
speak position. Further bill depressions of the button will re-operate the
buzzer at the called station. Depression of a second button releases the
first and any button not in the normal position is released when the
handset is replaced. Any number of calls may be conducted simultaneously. A
conference may be set up between any number of stations. To establish a
conference the originator calls each station in turn, and requests them to
call him back.
Stations will normally be numbered in
sequence according to their position on the multiple cable, but if a
customer has preference for a specific station arrangement they may be
numbered in any order. Should a customer wish, be may unclip the transparent
button covers, remove the numbers provided, and replace them with
designation labels to suit his own requirements.
All instruments are connected together by a grey or cream
plastic sheathed multiple cable, terminated on grey connexion boxes. The
maximum length of cable between the extreme end stations of the 6 or 16
station systems is 600 yards (reduced to 300 yards if any station has an
extension bell or buzzer). The maximum Length of cable on the 11 station
system is 500 yards (reduced to 200 yards when an extension bell or buzzer
is required). Where growth to a larger system can be foreseen, cabling for
the larger size may be installed initially so that only change of apparatus
is necessary when the growth matures. (Advice Notes should be suitably
annotated in such cases).
Power is supplied from a wall-mounted, mains-driven grey
power unit 127mm x 152mm x 101mm (5" x
6' x 4"), fitted near the
centre of the system. The customer provides a suitable 3-pin socket outlet.
In the event of power failure the system becomes inoperative.
 |
Close up of press buttons. The clear
plastic covers are removable to allow the installer to change
the numbers. The numbers are paper. |
|
 |
Wall mounted version |
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