APPROVAL No. S/1209/3/H/452512 (616) and S/1209/3/H/452513 (1236 & 2464)
by GEC and later, GPT. Also sold by Telephone Rentals as the Trinity.
Terminals to the right are the 1236 standard and executive.
The PKS2 816, 1236 and 2464 key telephone systems employ stored program control and
feature a wide range of intercommunication facilities. Many of the facilities can be
configured and allocated to stations (extensions) by system programming to suit individual
All systems in the PKS2 range consist of central equipment to which keystations and other
types of stations are connected radially. Trunk lines connect the system to the public
switched telephone network (PSTN) and/or PABX.
PKS2 816 systems cater for a maximum capacity of 8 trunks and 16 stations.
PKS2 1236 systems cater for up to 12 trunks and 36 stations but can be increased in
capacity by the addition of a 2464 extender unit.
PKS2 2464 systems consist of a combined 1236 base unit and 2464 extender unit and have a
maximum capacity of 24 trunks and 64 stations.
The central control unit for the 816 system has a built-in power supply. A separate power
supply unit provides power for 1236 and 2464 systems.
Three types of keystation are available for connection to PKS2 system:
Standard keystations have a key and lamp for each trunk, dedicated facility keys, ten
DSS/repertory keys and a dial keypad. A built-in microphone and loudspeaker enable
intercom 'voice calls'. Special versions are available with any combination of; handsfree
(loudspeech) operation on trunk calls, two-colour trunk lamps and/or inductively coupled
handset receiver for a deaf aid.
Executive keystations have the same features as the standard keystation but, in addition,
have a liquid crystal display that shows the date/time/dialled numbers and associated keys
to enable call duration timing and alarm clock functions. Full handsfree operation on
trunk calls is provided and special versions are available for bothway operation over a
trunk under power fail conditions.
Basic keystations have a single trunk key/lamp, fewer facility keys than the standard
keystation and no DSS keys. A built-in loudspeaker enables 'voice announcing' of intercom
calls but the basic keystation has no microphone.
Ordinary telephone stations can be connected to the PKS2 system and are able to take and
answer calls and use a limited range of facilities.
Special door phone units can be connected to provide handsfree inward calling to specified
The facilities provided by the PKS2 are listed and described in section 2 and the
equipment and its configuration are detailed in section 3 of this manual.
When a trunk is connected directly to the PSTN, the line loss should not exceed 10db.
When PKS2 Trunks are connected to a PABX and PSTN calls made via the PABX the line loss
between the PABX and PSTN should not exceed 8db
Dialling: DTMF or LD dialling.
Disconnect pulse speed and ratio is 10pps/33% make.
Power feed: Under normal operation power for the trunk call speech path is derived from
the PKS2 system power supply.
Under power-fail conditions, power for the speech path of dropback stations is derived
from the PSTN or PBX.
The ringer equivalence number for each trunk is 3.
Mains Voltage range: 225 to 270V AC - 50Hz
816 system - 160W max.
1236 system - 250W max.
2464 system - 490W max.
Mains plug fuse rating:
816 system - 3A
1236 system - 5A
2464 system - 5A
Power unit fuse ratings: Mains input 1.0A 4.0A 20mm glass
30V output 2.0A 10.0A 20mm glass
20V output 1.6A F2 3.0A 20mm glass
12V output 0.3A 0.5A 20mm glass
5V output 1.6A 6.3A 20mm glass
Central unit sizes
h w d Weight fully equipped
816 control unit: 31Omm x 54Omm x 25Omm 19Kg
1236 control unit: 41Omm 540mm 23Omm 20Kg
2464 extender unit: 41Omm 54Omm 230mm 16Kg
1236/2464 PSU 210mm 54Omm 23Omn 18Kg
Station line limits
Station type: line loop Cable length No of wires:
resistance 0.5mm 0.67mm
Keystation 50 ohms 300m 500m 4-wire
(Two twisted pairs)
POT 50 ohms 30Om 500m 2-wire
Doorphone (Twisted pair)
DSS Console 25 ohms 150m 250m 2-wire
Operating ambient temperature range,
control unit and keystations: Oc to 45c
Storage ambient temperature range: -20c to 70c
Humidity range: 10% to 95% non condensing