MODEL T336BCIRCUIT TEST SET

Operating Instructions

Wilcom

T336B Circuit Test SetOperating Instructions

810-311-007June 2005

Copyright (c) 2005 WilcomAll Rights reserved

Wilcom reserves the right to make changes to thematerial contained herein without notice and shall not beliable for errors contained herein or for incidental,consequential damage in connection with the furnish-ing, performance or use of this material.

This document may not be copied or duplicated in partor in whole for any purpose without the express writtenpermission of Wilcom.

Contents

Introduction ..........................................................Panel Controls and Connections ..........................Operation ..............................................................General Procedure ..............................................Circuit Measurement Procedures ......................

Application Notes ...............................................Performance Limits ..........................................Measurements at the Subscriber Location .......Measurements at the Central Office Location.. 9Balance Measurements .....................................

Specifications ......................................................Maintenance ........................................................

Battery Replacement .......................................Service & Repair .................................................Warranty ............................................................

Figures

1. T336B Front Panel ............................................2. Current Measurement Plot..................................

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The Model T336B Circuit Test Set is a portable, com-pact, combination level and noise measuring set. It is thefunctional equivalent to the Wilcom T136 series of testsets, but a 3-1/2 digit LCD display replaces the analogmeter. The T336B also has provisions for measuringDC resistance and voltage.

Powered by two 9-volt batteries, the T336B is designedto make circuit level and noise measurements over awide range of applications. When circuit loss, noisemetallic or noise to ground are displayed, a visualindication is given if the displayed reading is over orunder the accuracy range of the RMS to DC converter,the T336B measures DC volts from ring to tip lead andcurrent from the ring lead to ground. This measurementallows evaluation of station integrity. Since the officebattery potential, loop length, station ground resistance,and other variables affect the magnitude of current toground, exact ground resistance is difficult to deter-mine. The data pads that are used with the T336Binclude a table to facilitate determining if the stationground is at fault.

Circuit connection is accomplished by using three 5 ft.long leads colored Green for tip, Red for ring, andYellow for ground. These leads are permanently con-nected to the T336B and have universal test clips tofacilitate circuit connection.

Introduction

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Figure 1. T336B Front Panel

Features

÷1.8 8.8

...

PUSHTO

MEASGRN-TRED-RYEL-GND

DIAL &dc VOLTSGNDmA

LOOPmA

CKT LOSSdBmCKT NOISE

dBrnCPWR INFL

dBrnC

KILOHMSdcOHMS

dc

MODEL T336BCIRCUIT TEST SET

Wilcom

LO BAT

DIAL & MONITOR

CONNECTGROUND LEAD

FIRST

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Panel Controls and Connections

The following describes the function and operation ofthe T336B panel controls, connections, and indicators(see Figure 1 on opposite page).

The 3 1/2 digit LCD Display indicates measurementsfrom -199.9 to +199.9. A low battery indicator (LOBAT) is located in the upper left corner. Negativereadings are indicated by a minus sign that precedes thereading; positive numbers are indicated with no sign. Afixed decimal allows display accuracy at one-tenth of aunit.

The PUSH TO MEAS Switch enables display of themeasured level for a period of 60 seconds. The T336Bcircuits are activated only when you press the PUSH TOMEAS button.

The PUSH TO MEAS switch has to be operated for DCcurrent measurement. Polarity is indicated which elimi-nates the need for a polarity bridge.

The Function Switch is an 8-position rotary switch thatis used to select the desired measurement:

1. OHMS DC allows measurement of 0 to 1999 Ω usingthe tip (green lead) and the ring (red lead).

2. KILOHMS DC is the same as OHMS DC but witha range of 0 to 1999 kΩ.

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3.GND mA indicates the DC current drawn by a resis-tance of approximately 430 Ω connected between thering lead and the station ground. A positive reading isindicated with negative battery connected to the ringlead.

4. DIAL & DC VOLTS allows connection of a headsetto the line for dialing purposes. The DC VOLTSmeasures the typical line voltage on tip and ring at animpedance of approximately one MΩ . The DCvoltage range is 0 to ±199.9V. A positive reading isindicated with negative battery connected to the ringlead. Please note that the maximum voltage ratingfrom tip to ring is 96V AC or dc. The maximum ratingfrom tip or ring to ground is 500V DC or 250V AC.

5. LOOP mA (dc loop current) indicates the DC currentthat is drawn by a DC resistance of 430ý connectedacross tip-to-ring. A positive reading is indicated withnegative battery connected to the ring lead.

6. CKT LOSS (transmission) measurements can betaken over a level range of -55 to +5 dBm. The signallevel received is terminated and the level is readdirectly from the LCD display. Measurements may bemade at frequencies other that 1 kHz as the CKTLOSS response characteristic is flat from 200 to 4000Hz; 60 Hz is attenuated down 25 dB.

Panel Controls and Connections

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7. CKT NOISE (noise metallic) is measured on a C-Message weighted basis. Noise level readings on thedisplay vary at a greater rate than those on an analogmeter as it has no mechanical damping effect. Thedisplay is updated two or three times per second fornoise fluctuations.

8. PWR INFL (noise-to-ground) is measured betweena circuit and ground on a C-Message weighted basis.The input circuit in this position has an impedancegreater than 10 MΩ dc; tip and ring are taken togetherto ground.

The PWR INFL display is calibrated to read the noise toground directly in dBrnC (600 Ω voltage equivalent).

Dial and Monitor Connections from the front panelprovide convenient locations for connecting a handset/headset.

Connections to the circuit to be tested are made with theuniversal clips on the 5 ft. long leads. The leads are colorcoded green for tip, red for ring and yellow for ground andare also marked T for tip, R for ring, and G for ground.These leads are permanently attached to the set.

Panel Controls and Connections

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Operation

The following describes general operating instructionsfor the T336B. Also described are the procedures thatyou can use to make circuit measurements.

General Procedure1. Connect the test leads to the circuit under test using the

green lead for tip, the red lead for ring and the yellowlead for ground.

CAUTION: GROUND should be connected first.

2. Connect a handset/headset to the DIAL & MONI-TOR posts or jack. Set the function switch to DIAL &DC VOLTS. When you hear a dial tone you can thencall the desired number.

3. Press the PUSH TO MEAS button each time you wishto make a measurement.

Circuit Measurement ProceduresOHMS DC: Circuit continuity and resistance may bechecked in this position. Resistance measurements canbe displayed from 0 to 1999 Ω. Refer to Specificationsfor display accuracy. Use the tip (green) and ring (red)leads for resistance measurements.

KILOHMS DC: This function is the same as OHMS DCabove but with a measurement range of 0 to 1999 kΩ.

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OperationGND mA: This measurement is useful for evaluatingstation grounds. Plot this measurement on the reverseside of the Wilcom Data Reporting Pad as I (G)mA. Thesecond measurement is LOOP mA or I(L)mA.( See Figure 2 )

DIAL & DC VOLTS: Use this position when calling anumber. Then check the line voltage after the callednumber answers.

LOOP mA: This measurement, along with the GND mA measurement, is plotted on the reverse side of theWilcom Data Reporting Pad. The intersection of thetwo points indicates the condition of station ground.

CKT LOSS dBm: Dial the milliwatt generator at the centraloffice. When the tone is received measure the level.Knowing the output level of the generator and the mea-sured level, the circuit loss can be determined (e.g. genera-tor output level equals 0 dBm, measured level equals -15dBm, therefore, the CKT LOSS equals 15 dB).

CKT NOISE dBrnC: Dial the quiet (or balanced) termi-nation at the central office. When the termination isreceived measure the noise metallic.

PWR INFL dBrnC: Establish connection to a quiet (orbalanced) termination. Noise to ground can now bemeasured. The reading is displayed directly in dBrnC,(600 Ωvoltage equivalent).

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Figure 2 Current Measurement Plot

Operation

Note:This chart shows acceptable readings above the curved line andunacceptable readings below the curved line. By plotting the loopcurrent I(L)mA and the ground current I(G)mA it is possible todetermine if the station ground is aceptable or not. Where the tworeadings intersect is the point of acceptability or unacceptability.

To use the chart, first measure and plot the loop current I(L)mA,then measure and plot the ground current I(G)mA. For example; ifthe loop current is 35ma and the ground current is 60ma, anadequate station ground exists.If the intersection of the twomeasuremtns fall below the curved line then the station groundand bond should be checked.

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The following describes use of the T336B in takingnoise measurements at the subscriber and central officelocations, and examining circuit balance.

Performance LimitsThe measurement ranges of the T336B are designed tobe within the normally acceptable limits of circuit loss,circuit noise (noise metallic) and power influence (noiseto ground). Should the measured reading exceed theaccuracy range of the built-in RMS to DC converter, theunused decimals and colon flash on the display.

Measurements at the Subscriber LocationMeasurements may be made from the terminal block orprotector block at the customer's location. It is notnecessary to disconnect the customer's equipment, butthe equipment must be in the ON HOOK conditionwhen making measurements. The leads on the T336Bare connected to the circuit using the green lead for tip,the red lead for ring and the yellow lead for ground. Agood ground, preferably the ground at the protectorblock, must be available to make power influencemeasurements.

Measurements at the Central Office MainframeNoise measurements may be made at the main frame ina C.O. toward the subscriber or toward the officeequipment.

Application Notes

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Application NotesToward Subscriber. Meaningful noise measurementscan only be made toward the subscriber when there is atermination at the far end. If a section of the subscribersloop is to be measured, a termination should be con-nected at the far end of the section. A Wilcom ModelT279 Circuit Termination Set is useful in providing sucha termination. Unterminated measurements do not pro-vide useful data for analyzing noise problems. How-ever, if a large number of unterminated loops are tested,useful statistical information can be compiled on theextent of noise on loops out of a central office. Pleasenote that heat coils should be removed during testing.

To Central Office Equipment. To determine the level ofnoise that originates in the central office and the balanceof the office equipment, remove the heat coils andconnect the tip and ring leads to the terminals of theoffice equipment. Connect the ground lead to C.O.ground bus and dial the quiet termination to make CKTNOISE and PWR INFL measurements.

If the induced longitudinal voltage is low, it may not bepossible to make noise measurements. It is then neces-sary to introduce an external longitudinal voltage at afixed frequency; any signal source between 500 and1000 Hz is satisfactory. A Wilcom Model T137B isuseful for providing a balanced terminating circuit towhich a longitudinal voltage source can be connected.

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Application Notes

Balance MeasurementsCircuit balance can be determined from the CKT NOISEand PWR INFL measurements made with the T336B byusing the following formula:

Balance (dB) = PWR INFL (dBrnC) - CKTNOISE (dBrnC)

The balance of a circuit determines how sensitive it is tothe induction of noise. The following values provide aguide for determining acceptable balance:

Balance ConditionOver 60 dB Excellent50-60 dB Good40-50 dB FairUnder 40 dB Poor

Typically, any balance under 50 dB requires improve-ment, particularly when the power influence is high, i.e.,over 75 dBrnC as measured on the T336B. If powerinfluence is low, a greater degree of imbalance can betolerated. However, if the power influence should in-crease, the practice is to get as high a balance aspossible.

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Specifications

Manufacturer WilcomModels T336BName Circuit Test Set

OperationalRangesOHMS DC: 0 to 1999 Ω , 1Ω resolution

KILOHMS DC: 0 to 1999 kΩ , 1kΩ resolution

GND mA: 0 to ±199.9 mA DC (0.1 mAresolution) in 430 Ω

dc VOLTS: 0 to +199.9V DC (0.1V resolution),across 1 mΩ resistance

LOOP mA: 0 to ±199.9 mA DC (0.1 mAresolution) in 430 Ω

CKT LOSS: -55 to +5 dBm, 0.1 dB resolutionin 600 Ω

CKT NOISE: 0 to 60 dBrnC in 600 Ω , 0.1 dBresolution

PWR INFL: 50 to 110 dBrnC, 0.1 dB resolution

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Accuracy (@ 25°C):OHMS DC: 400 to 1000 Ω ; ±1%

Other readings: ±2% + 2Ω

KILOHMS DC: ±3% + 2 kΩ

dc Volts: ±2% + 0.2V

GND mAat 20 mA: ±0.2 mAOther readings: ±2% + 0.2 mA

LOOP mA at 20 mA: ±0.2 mAOther readings: ±2% + 0.2 mA

CKT LOSS(w/ 1004 Hz tone): ±0.1 dB from -10 to 0 dBm

±0.2 dB from -40 to +5 dBm±0.3 dB from -55 to -40 dBm

CKT NOISE(w/ 1004 Hz tone): ±0.3 dB at 30 dBrnC

±0.5 dB from 20 to 60 dBrnC±1.0 dB from 0 to 20 dBrnC

PWR INFL: ±0.5 dB from 70 to 110 dBrnC±1.0 dB from 50 to 70 dBrnC

Specifications

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Specifications

Change w/ temp relative to 25ºC:

dc measurements: ±1% max, -20º to 50ºC

LOSS and NOISEmeasurements: ±0.2 dB max. at 0º to 50ºC

±0.5 dB max. at -20ºC

Frequency ResponseCKT LOSS:4 kHz: Flat within accuracy specs200 Hz to 400 Hz: ±0.5 dB relative to 1004 Hz4 kHz to 15 kHz: ±0.5 dB relative to 1004 Hz60 Hz down at least 20 dB relative

to 1004 Hz

CKT NOISE: C-Message Weighting

PWR INFLUENCE: C-Message Weighting

Input ImpedanceOHMS DC: High resistance 1 mA

current source

KILOHMS DC: High resistance 1µAcurrent source

GND mA: 430Ω ±1% DC ring-to-ground;tip open-circuit

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SpecificationsDIAL & DC VOLTS: Tip and Ring directly con-

nected to DIAL & MONITORterminals, 1 MΩ shunt

Other FUNCTIONPositions:Tip-to-Ring: 430Ω ±1% dc, 600Ω acReturn loss: >30 dB with respect to 600 Ω

200 Hz to 15 kHz Tip-Ring to GND: >10 MΩ dc, >100 kΩ AC

MiscellaneousMonitor Output: Balanced 600 Ω output, approx.

0.25V at center of each auto-range. At DIAL & MONITORterminals during CKT LOSS,CKT NOISE, and PWR INFLmeasurement.

Push to Measure: Push button ONAuto-off after approx. 60 sec.

Detector: True rms

Longitudinal Balance: >100 dB at 100 Hz, decreasing 20dB/decade at higher freq.

Digital ReadoutResponse: Approx. 1 second for 10 dB level

change. Two or three updates/second for noise fluctuations.

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Specifications

Tip or Ring to GND: DC: 500V, AC: 250V

Maximum RatingsTip-to-Ring: AC to DC, 96V applied

through 400 Ω

PowerBatteries: Two 9V NEDA 1604 or1604A

Battery Life: 30 hours continuous, or 1800operations of the PUSH TOMEAS switch.

EnvironmentalOperating:Operating Temp.: -20° to +50°CHumidity: 90% at 35°C, 40% @50°CAltitude: to 5000 metersStorage Temp.: -50° to +70°C

PhysicalWidth: 4-3/8 in. (11.0 cm)Height: 6-3/8 in. (16.0 cm)Depth: 4-7/8 in. (12.5 cm)Weight: 2.9 lbs. (1.3 kg)

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MaintenanceBattery ReplacementTo replace the two 9-volt batteries, remove the unit fromthe case by loosening the four screws that are indicatedwith arrows on the panel (Figure 1). The batteries canthen be easily replaced.

CAUTION: To prevent possible circuit malfunction,power off the unit before removing the batteries.

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For service or repair follow the procedure below:

1. Call Wilcom Customer Service. Support personnelwill determine if the equipment requires service, repairor calibration.

2. If the equipment must be returned to Wilcom forservice, Wilcom Customer Service will issue a ReturnMaterial Authorization (RMA) number and the follow-ing address for return:

Wilcom 73 Daniel Webster Highway Belmont, NH 03220 TEL (800) 222-1898 (USA only) or (603) 524-2622 FAX (603) 524-3735 www.wilcominc.com

IMPORTANTNever send any equipment back to Wilcom withouta Return Material Authorization (RMA) number.

3. Pack the equipment in its original shipping material.Be sure to include a statement or report fully detailingthe defect and conditions under which it was observed.

Service and Repair

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Also be sure to include a contact name and telephonenumber.

4. Return the equipment, prepaid, to the above address.Be sure to write the RMA on the shipping slip. Wilcomwill refuse and return any package that does not bear theRMA.

Ordering InformationOrders for any of the Wilcom products and any of theiroptional accessories should be directed to the addressshown above.

Service and Repair

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WARRANTYAll products are warranted against defects in materials andworkmanship. This warranty applies for a period of two (2)years from date of delivery, except for Fiber Optic instrumen-tation and equipment which have a one (1) year warranty onparts and two (2) years on labor. (The only exception in thedigital testing equipment is the D550 Shark, which has a war-ranty of one (1) year from date of delivery.) Wilcom's obliga-tion under this warranty is limited to servicing or adjustingeach instrument returned to its factory within the warrantyperiod, and to replace any components found to be defective.If determined that the defective condition is a result of mis-use or abnormal operation, repairs will be billed.

LIMITATION OF WARRANTYThe foregoing warranties are the exclusive warranties pro-vided by Wilcom. Wilcom will not be liable for any special,indirect, incidental or consequential damages whatsoever re-sulting from loss of use, loss of data or loss of profits arisingout of or in connection with the use or performance of theproduct, even if Wilcom has been informed of the possibilityof such damages in advance. All implied warranties, includ-ing without limitation warranties of merchantability and fit-ness for a particular purpose, as well as warranties arisingfrom a course of dealing or usage of trade are expressly dis-claimed.

PROPRIETARY INFORMATIONThe information contained in this manual is the propri-etary material of Wilcom, and may not be reproduced,used for manufacturing purposes, or disclosed to others

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