Manual - GW Instek
Contents
1. Front Panel GVT 427B User Manual DISCONNECT SUPPLY BEFORE CHANGING RANCE 2 115 POWER 6 0 WATTS 8 5 amp WARNING TO AVOID ELECTRIC SHOCK THE POWER CORD PROTECTIVE GROUNDING CONOUCTOR MUST BE CONNECTED TO GROUND FOR CONTINUED FIRE PROTECTION REPLACE ONLY SPECFIEC TYPE AND RATED FUSE NO OPERATOR SERVICEABLE CONPONENTS INSIDE DO NOT REMOVE COVERS REFER SERVICING 10 QUALIFIED PERSONNEL Rear Panel GVT 427B User Manual Operation Method A Voltage measurement 1 2 Turn off the power Check the ZERO setting of the pointers If there is offset you could use a screwdriver to adjust the zero adjustment screw at the center of the meter front cover Plug the AC plug into the AC line Set the RANGE to 100 V and turn on the power Connect leads to the INPUT terminal and the load is under testing Alter the RANGE selector switch until the pointer is at a position which located at 1 3 of the scale therefore the reading can be taken easily B Use of decibel ranges There are two dB scales provided on the dial which have been calibrated as 1 OdB 1V 0 dBm 0 775 V 1 mW into 600Q dB Bel is a logarithmic unit which expresses the ratio of two powers One decibel abbreviated dB is one tenth of a Bel The dB is defined as follows2. dB 10 log If the impedance is at the place where and P are equal to each other the ratio of power could be expressed as follows dB 20 log E2 E1 20 105 1 GVT 427B User Manual Decibel is originally the ratio of power as explained above However the logarithm of the ratio of other values ratio of voltage or current can also been called decibel For example If the input voltage of an amplifier is 10 mV and its output voltage is 10 V the degree of amplification could be 10 V 10 mV 1000 times This is also expressed in dB as follows Degree of amplification 20 log 10 V 10 mV 60 dB 2 dBm dBm 15 the abbreviation of dB mW This decibel value expressed the power ratio with respect to 1 mW Normally dBm implies the condition where the power exists in an impedance of 600 Q Therefore 0 dBm can be signified as the following 0 dBm 1 mW or 0 775 V or 1 291 mA 3 power or voltage levels are determined by adding up the scale readings and the selected RANGE settings Example Scale RANGE Level 1 dB 420dB 19 2 dBm 10 dBm 12 dBm GVT 427B User Manual 4 The dB and dBm scales of the indicating meter are as stated the following 12 GVT 427B User Manual Specifications This section contains a table of GVT 427B characteristics Table 1 Specifications GVT 427B Indicating Meter 2 Pointers Bl
3. When the range selector switch is setting at 100 mV the output voltage will be approximately equal to the input voltage However when the range selector switch is setting to the next higher or lower voltage range the amplification factor is decreased or increased by 10 dB respectively The maximum voltage of DC isolation is 12 V peak value 10 Mode switch If this button is setting as DISENGAGED the CH 1 and CH 2 range selector switches could select their related own ranges If the mode switch has been pressed the CH 1 range selector switch could select both CH 1 and CH 2 voltage ranges simultaneously and the CH 2 range selector switch would be ineffective 11 Grounding selector switch If this switch is setting to the upper position the CH 1 and CH 2 Input Command Lines are isolated from each other and they are floated relative to chassis ground through a resistance of 100 If the switch is setting the down position both lines could be connected directly to the chassis The maximum voltage of DC isolation is 30 V peak value 12 Power Indicator 13 Power Switch 14 Appliance AC Inlet GVT 427B User Manual PANEL DESCRIPTION GVT 427B 98 og8 1v 600K mw AC MILLIVOLIMETER 2 CHANNEL Cna RANGE RANGE ely Eo 5 i HOE
4. scales GVT millivoltmeter adopts a special extended scale which has a reading range larger than the conventional full scale 0 to 1 0 to 1 12 to 3 1 3 2 to 3 5 20 to OdB to 1 dB 20 to 2 dBm to 3 2 dBm Note that the term full scale considers 1 0 on the 0 1 12 scales as the rated value The red W mark is setting at 1 0 on the outermost scale GVT 427B User Manual Panel Description 1 Meter Provide easy readings for both voltage and dB scales For GVT 427B the black pointer is CH 1 and the red one is CH 2 2 3 ZERO adjustment Mechanical ZERO adjustment for the pointer For GVT 427B the black mark screw 2 is to adjust CH 1 pointer whereas the red mark screw 3 is to adjust CH 2 4 5 CH 1 and CH 2 Range selector switch 10 dB step attenuator to select a desired voltage range for an easy readout When the mode switch 10 of GVT 427B is DISENGAGED CH 1 and CH 2 range can be selected independently However when the mode switch 15 DISENGAGED the CH 2 range will change according to the selected CH 1 irrespective of the CH 2 selector switch 5 position 6 7 CH 1 and CH 2 input connector respectively The terminal where the measured signal is applied The maximum voltage of DC isolation is 30 V peak value GVT 427B User Manual 8 9 CH 1 and CH 2 Output connector respectively Provide output signals when the meter is used as a preamplifier
5. the wires in main leads may not correspond with the colours marking identified in your plug appliance proceed as follows The wire which is coloured Green amp Yellow must be connected to the Earth terminal marked with the letter E or by the earth symbol or coloured Green or Green amp Yellow The wire which is coloured Blue must be connected to the terminal which is marked with the letter N or coloured Blue or Black The wire which is coloured Brown must be connected to the terminal marked with the letter L or P or coloured Brown or Red If in doubt consult the instructions provided with the equipment or contact the supplier This cable appliance should be protected by a suitably rated and approved HBC mains fuse refer to the rating information on the equipment and or user instructions for details As a guide cable GVT 427B User Manual of 0 75mm2 should be protected by or 5A fuse Larger conductors would normally require 13A types depending on the connection method used Any moulded mains connector that requires removal replace ment must be destroyed by removal of any fuse amp fuse carrier and disposed of immediately as a plug with bared wires is hazardous if a engaged in live socket Any re wiring must be carried out in accordance with the information detailed on this label GVT 427B User Manual Introduction GVT 427B is versatile AC voltmeter which is able to measure AC voltage from r
6. GVT 427B User Manual GVT 427B User Manual Contents Page SAFETY TERMS AND SYMBOLS Safety Terms and Symbols 45 1 These terms may appear in this manual or on the product 4 Preliminary 5 WARNING Warning statements identify condition Panel Description 000 0000ccceeeeee eens 6 practices that could result in injury or loss of life Operation 10 CAUTION Caution statements identify conditions or Specifications cece ee eee e nee en ees 13 practices that could result in damage to this product or other property Maintenance ccc ccc ece neces eee eeeeeaeee 16 Cleaning vagade aus 16 The following symbols may appear in this manual or on the product Troubleshooting eceeeeeeeneeeeeenees 16 DANGER High Voltage Interchangeable 17 ATTENTION refer to Manual Protective Conductor Terminal Ground Earth Terminal L De GVT 427B User Manual FOR UNITED KINGDOM ONLY NOTE This lead appliance must only be wired by competent persons WARNING THIS APPLIANCE MUST BE EARTHED IMPORTANT The wires in this lead are coloured in accordance with the following code Green Yellow Earth Blue Neutral Brown Live Phase As the colours of
7. ack and Red 105mm in scale length Scale Values V ms Value of sinusoidal wave dB value with 1 V as 0 dBm dBm value with 1 mW Range Select Mode Independent tracking control mode for each channel range Voltage 12 ranges 300 uV 1 3 10 30 100 300 mV Measurement 1 3 10 30 and 100 V of full scale Decibel Range 12 range 70 to 40 dB in increments of 10 dB Decibel Scale 20 1 dB 0dB 1 V 20 to 3 dBm 0 dBm 1 mW 600 QJ Voltage Accuracy Within 3 of full scale at 1 kHz 13 GVT 427B User Manual Table 1 Specifications Cont 3000 range Frequency Response lt Reference 1 kHz From 20 Hz to 200 kHz lt 3 From 10 Hz to 500kHz lt 10 Other ranges From 20 Hz to 200 kHz lt 3 From 10 Hz to 1 MHz lt 10 Distortion Factor lt 2 of full scale at 1 kHz Input Impedance Approximately 1 MQ Input Capacitance lt 50 pF Input Maximum 300 at 300 uV 1 V ranges Voltage 500 V at 3 V 100 V ranges DC AC peak DC isolation 0 1 Q 100 10 selectable Resistance Maximum Voltage of 30 V peak value at 100 KQ isolation DC isolation AC Output Voltage 0 1 Vins 10 for each range of 1 kHz at full scale without load AC Frequency 10 Hz 1 MHz lt 3 Response reference 1 kHz without load Stability against Line Indication change with respect to line voltage Voltage Fluctuation fluctuation of 10 is within 0 5 of
8. anges of 10 Hz to 1 MHz with full scale ranges from 300 uV to 100 V The dB scale measures 1V as OdB and ranges from 90 dB to 41 dB The 600 1mW dBm scale ranges from 90 dBm to 43 dBm The scales on the meter are graduated up to 1 1 for 1dB and these extended scales are especially useful when measuring the characteristics of audio amplifiers In addition both instruments can give AC voltage output of approximately 0 1V in full scale from the output terminals and the measurements can therefore be monitored GVT 427B is a two channels voltmeter with isolated output for each channel which enables it to be used as a two channels preamplifier GVT 427B User Manual Preliminary Notes 1 Chassis grounding terminal Make sure the chassis ground terminal is connected to the earth before inserting the power plug into the main supply 2 Maximum input voltage The voltmeter may be damaged if any input voltage exceeding the specified voltage is applied to it The specified voltage is determined by adding the peak value of the input signal and the superimposed DC voltage 300 V for the 300 uV ranges and 500 V for the 3 V to 100 V ranges Connection leads When the measured signal level is low i e 300 uV or the measured signal source impedance is high the input line is susceptible to external noise To resist the noise shielded wires or a coaxial cable should be used depending on the noise frequency 4 Full
9. full 14 GVT 427B User Manual AC Power 115 230 Vac 50 60 Hz Requirement Table 1 Specifications Cont Foye 8 5VA or 5 0 Watts Maximum Consumption Fuse Replacement for 115 Vac selected a ac Fuse Replacement for 230 Vac selected e 2 aye 0W as Indoor user Altitude up to 2000M Operation Installation Category Environment Pollution Degree 2 Operating Temperature 0 C to 40 C lt 80 relative humidity 130 W x 210 H x 295 D mm Approximately 2 84kg Dual scales in different colors Between the input common and chassis 15 GVT 427B User Manual Maintenance This section includes the basic maintenance information for GVT 427B Cleaning To clear GVT 427B use soft cloth dampened in a solution of mild detergent and water Do not spray cleaner directly onto the instrument since it may leak into the cabinet and cause damage Do not use chemicals containing benzine benzene xylene acetone toluene or similar solvents Do not use abrasive cleaners on any portion of this equipment Troubleshooting Troubleshooting the GVT 427B is limited to checking the input power fuse If you have other operational difficulties with your GVT 427B contact your Good Will representative for assistance WARNING To avoid electrical shock the power cord protective grounding conductor must be connected to gt ground WARNING To continued fire protection Replace fuse with the specified
10. type and rating and disconnect the power cord before replacing fuse GVT 427B User Manual Interchangeable Parts Interchangeable parts can be ordered from your authorized Goodwill dealer directly Accessories The items are shipped with the GVT 427B as following Table 2 Accessories Test Leads GTL 101 x 2 1100 TL101U0 for GVT 427B 17
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