+ ------------------ British Telecom Testing Equiptment ------------------ + ¦ M M ¦ | e Typed by Dosile & Psyclone e | ¦ D D ¦ + -------------------------------- 132 C --------------------------------- + > i N D E X < 1. General Desciption 2. Description of Equiptment Items 3. Principle of Operation 4. Using the Oscillator 87G 5. Using the Amplifier 109H 6. Care and Maintenance of the Tester 1. General Desciption a. Oscillator 87G b. Amplifier 109H c. Receiver Headgear 17A d. Receiver Handgear 18A e. Adapter Test 18A f. Cord Connecting 2/26A g. A storage/carrying satchel h. This handbook The powered items (Oscillators and Amplifier) are primary cell battery operated units. The Tester 132C enables cable pairs to be identified quickly in BT local networks, provided that the pairs are in good electrical condition. Where insulation resistance is low or where pairs are subject to short circuits, contacts or disconnections, location and identification may be more difficult. The equipment must only be used in the manner and purpose specified in this handbook or approved documation. No unapproved modifications are to be made to this equipment. 2. Description of the Equipment Items 2.1 OSCILLATOR 87G -General The signal output is provided via two 4mm sockets enabling the use of standard leads. A moniter socket is provided to enable connection of a suitable headphone (Receiver headgear 17A or equivalent) The Osciallator provides a kHz signal output to line. This signal may be continuous, or interrupted at between 2 and 10 pulses. The output is set by a single rotary control. If desired, the output signal can be monitiored whilst the rate is being set. This is achieved by listening to a headphone connected to the monitor socket and with the output sockets shortened (looped) together. -DETECTION OF LINE STATUS The monitor headphones provide an indication of a satisfactory line connection and also of temporary shorting of the connected line. When the Oscillator is sending a signal to line, a low level signal will be heard in the headphone. The headphone output level will rise briefly (for approximately 3 seconds) when the line is shorted along it's length. The `SHORT' indicator will illuminate during this period. The `short' condition may also be indicated when the line connection is first made. The indication will depend on the line length and the Oscillator model. NOTE : a) When the pair is shorter than 100 metres, the indication of line presence may not operate reliably. b) When the pair is longer than 2.5 kilometres, the shorting conditions will not operate reliably. -BATTERY STATE INDICATION. A battery state indicator lamp (`BATTERY') is provided on the Oscillator. When the Oscillator is on, this indicator will flash at approximately at 2 second intervals. This signifies that the battery voltage is adequate. If the voltage falls to a level such that the battery requires replacement, the indicator will flash at a faster rate (typically 7 times a second). In addition, the signal output to line will change. This will give an indication to the Amplifier operator that Oscillator battery failure is imminent. (typically half an hour after the output signal changes). The output signal change takes the form of a long periodic interrupt, i.e. It turns on and off at two second intervals. -CONNECTION LEADS The oscillator comes complete with a set of connection leads and clips. Alternatively, Cords Test 1/500A and Clips Test 38A may be used. -IMPORTANT SAFETY NOTICE: The monitor (headphone) output is only suitable for use with Receivers Headgear 18A or 18A and Headsets 7A or 8A. Use of other headphones may result in the users audio exposure exveeding safety limits. 2.2 AMPLIFIER 109H -GENERAL The amplifier has an integral probe and a loudspeaker output. As the amplifier probe tip approaches the cable pair which the oscillaor signal is connected to, the clicks generated by the speaker become more frequent. This enables the pair to be located even when high background noise levels exist. A rotary sensitivity (gain) control is provided so that the Amplifier may be adjusted to suit the signal levels being detected. -BATTERY STATE INDICATION When the Amplifier is switched on or off, the red indicator light will flash once. This indicates that the battery voltage is adequate. If the voltage falls below an acceptable level, the light will be on continuously. The battery must then be changed. -HEADPHONE SOCKET The output socket at the rear of the Amplifier allows the connection of a headphone (receiver Headgear 17A or equivalent). Only the received 1kHz signal is provided to the headphone output. The click rate signal and the loudspeaker output are disabled when the headphone is plugged in. The headphone output system should be used when working in quiet areas on customers premisies, or where interfering signals from other sources are present on the pair being traced. -IMPORTANT SAFETY NOTICE The headset is only suitable for use with Receivers Headgear 17A or 18A and headsets 7A or 8A. Use of other headphones may result in the users audio exposure exceeding safe limits. 2.3 RECEIVER HEADGEAR 17A This the `standard' headphone for use with the Amplifier or Oscillator. 2.4 RECEIVER HEADGEAR 18A This headphone is designed for use with Helmets Safetly .... 2.5 ADAPTER TEST 49A The adapter plugs into the customers' line jack unit to enable test access to all six connections. The adapter is numbered to correspond with the numbered rear wire connections of the line jack unit. 2.6 CORD CONNECTING 2/26A The cord is provided for connecting between either the Amplifier of Oscillator and a Telephone 286. This enables the telephone headset to be used for communication and tone tracing. 3. PRINCIPLE OF OPERATION -GENERAAL The Oscillator provides a 1kHz signal which is connected to the pair of wires to be traced or identified. The signal power is limited to 20mW. To minimise interference to adjacent lines a sine wave is used. The signal sets up electromagnetic and electrostatic fields in the vicinity of, and along the length of the pair. These fields can be detected by means of either an electromagnetic or electrostatic probe. The signal for these probes is then amplified and presented to the user through either a loud speaker or a headphone (receiver Headgear 17A or equivalent). Induction of the 1kHz signal into adjacent pairs balances itself out giving negligble crosstalk (interference) to working circuits. -ELECTROMAGNETIC DETECTION Where a magnetic detection system is required (usually only necessary where idenfication of a cable is required) the Tester 453A is used. This is used in conjunction with the Oscillator 87, provided as part of the Tester 132C. Principles of magnetic detection and the use of the Tester 453A are detailed in the users handbook with the tester 453A. -ELECTROSTATIC DETECTION The Tester 132C provides the 1kHz Oscillator and an electrostatic detection system. The electrostatic method is employed for the locating and identification of individual cable pairs. For electrostatic detection the oscillator signal is connected directly across the cable pair to be identified or located. If possible, the pair should be open circuit to ensure the highest signal voltage at the detection point. The amplifier 109H detects the electric field resulting from the voltage across the pair. For maximum flexibility, two output systems have been incorporated into the amplifier. The loudspeaker control is the `normally' used system. This is built into the Amplifier. The level of the signal detected by the probe is represented by a varible click rate (pitch) output from the loudspeaker. The closer the probe is to the desired pair, the higher the click rate of the output from the loudspeaker. The alternative to this system is the headphone output. This enables the user to listen to the signal being radiated by the pair being traced. The closer the Amplifier is held to the pair, the louder the sound output will be from the headphone. 4. USING THE OSCILLATOR 87G The oscillator is connected to the pair to be traced at a convientent point, typically at a flexiblilty point such as an exchange frame or a street cabinet. To prevent interference to customer service, care must be taken to avoid connecting the oscillator to working circuits. Plug the connecting leads supplied into the output sockets of the oscillator. Switch the Oscillator on and connect the leads to A and B wires of the cable pair to be traced using the appropiate test clips or adaptors. (As the connection is made the `SHORT' indicator on the top of the Oscillator may illuminate briefly). If a headphone is connected, satisfactory connection to line is indicated by a low level tone (the tone may be at the higher `short' indication level for a brief period after inital connection). Adjust the Oscillator output to give an interupted or continuous tone as required. Always replace the headphone socket sealing plug when the headphone is not connected. The Oscillator must not be connected between earth and the wires as this will increase the level of tone induced into other pairs. This will also make positive tracing and identification of the pair difficult and could result with interference with communications traffic on the cable. The Adaptor Test 49A supplied with the Tester 132C ensures the Oscillator to be connected to a Line Jack Unit. Other adaptors are often provided with frame and cabinet block systems for test access purpose. These should be used, where available, to ensure a reliable connection to the pair to be traced. Connection to a `live' exchange line will reduce the signal available on the line and may make the tracing operation more diffilcult. If practical, where the Oscillator is connected at an exchange frame, the exchange connection should be removed by the approved method for the type of block being used, i.e insertion of the appropriate wedge or removal of the line fuses. 5. USING THE AMPLIFIER 109H 5.1 LOCATION OF A PAIR AT A CABINET (OR PILLAR) One press of the `ON' switch turns the Amplifier on. The loudspeaker output will emit two short `clicks' every second, even when no signal is being received by the probe. A further press of the switch turns the amplifier off. Initially, set the sensitivity control to it's mid point. Move the amplifier over the terminal strips where the wanted pair is expected to be. If the click rate of the amplifier does not change, turn the sensitivity control toward its `FAR' setting and repeat the search. If the click rate does not increase at any point, then the rest of the cabinet should be searched with the Amplifier until the approximate location of the pair is found. The sensitivity control is then turned towards it's `NEAR' setting until sufficient discrimination is available to enable accurate location of the pair. If the identification is in doubt, this may be confirmed by shorting the wires if the identified pair together - when this is done the click rate of the Amplifier will drop significantly if the pair is the correct one. Where applicable, metallic contact must be made by use of the appropriate test clips or adaptors. The exact method employed will depend on the type of cross connection system fitted in the cabinet. On no account is contact to, or shorting out of, the pair to be achieved by cutting into cable insulation with knives or other insulation piercing devices. It should be noted that the Amplifier discrimination will always be better between pair if the sensitivity setting is kept as low as possible, i.e. close to the `NEAR' setting. 5.2 LOCATION OF A PAIR AT A DISTRIBUTION POINT (DP) For pair location at a DP the Amplifier sensitivity control will normally need to be set close to the `NEAR' setting. Location is usually so positive that shoring out the pair is unnecessary. 5.3 LOCATION OF A PAIR IN A CABLE JOINT To find a pair within a joint the Amplifier sensitivity should be adjusted such that an increase in click rate is achieved when the amplifier probe is close to the joint. Search of the units of the joint to identify the unit containing the wanted pair. When this has been located, the sensitivity is further reduced (turn the control towards the `NEAR' setting) to allow the individual pair to be found. Maximum click rate will be achieved when the probe is adjacent to the `A' or `B' wire with a drop in click rate noted when the probe is placed between the two wires. If more positive indentification is needed, the located pair can be shorted out to confirm the identification. Ensure that the pair is correctly reinstated using approved practice. 5.4 CABLE CHANGEOVER OPERATIONS The use of the Amplifier is as described for the location of pairs in a joint. When the Amplifier operator shorts to verify the location, the operator at the Oscillator end will receive an indication of this (see section 2.1 - DETECTION OF LINE STATUS). This will indicate correct location of the pair to both users. The Oscillator monitor output and/or the Amplifer headphone output may be fed into the `AUX' input of the Telephones 286 being used to communicate between the two operators. The Cord Connecting 2/26A is used to make the connection. This facility connects the Oscillator monitor output or the Amplifier headphone output to the receiver of the Telephone. This enables the telephone headset to be used for communication and tone tracing. 6. CARE AND MAINTENANCE OF THE TESTER The tester 132C and it's component parts are designed for use in an external engineering enviroment. When the Tester is not in use, additonal protection is providied by the storage pouches and carrying satchel. The headphone socket sealing plug forms an important seal against the ingress of moisture. Always replace the headphone socket sealing plug when the headphone is not connected. The only routine maintenance required is to keep items forming the Tester as clean and dry as is practical. If cleaning is necessary, a cloth moistened with a warm, mild detergent solution should be used. It is particulary important that spent batteries are removed from the Amplifier and Oscillator. Only maganese alkaline batteries are to be used in this items, i.e LR6 for the Oscillator 87G, 6LR61 (6LF22) and for the amplifier 109H. [oFFiCiAL eND oF dOCUMENT] Right, in addition to all this, it is possible to trace a cable pair without the use of an Oscillator.. the test service 176 can be used for a local number and will apply a trace tone to the number you enter after 176 (full national code must be used). To check for correct line, then apply a ground of 2kms thru the cable pair, if the correct line has been identified then the user dialling 176 will recieve the NU tone (continuous tone). Whilst this service is in use, no one may dial the subscribers line as it would be busied out.