Tektronix 7A29 User's Manual
Contents
1. Signals of more than 50 V peak amplitude must be connected with input switch in OFF position so that input coupling capacitor is precharged 10 V de within 2 V de 10 V de within 2 V dc or approximately 10 V rms up to 100 MHz Less than 30 ms for 50 V dc of either polarity 40 ms to 150 ms for 25 V dc of either polarity De coupled 50 Q within 1 Q Ac coupled 50 Q within 1 Q in series with at least 1 6 uF 0 05 or less in a 1 GHz 120 time domain reflectometer system 1 4 1 at 10 mVOLTS DIV 1 20 1 from 20 mVOLTS DIV to 1 VOLTS DIV de to 1 GHz 1 4 1 at 10 mVOLTS DIV 1 20 1 from 20 mVOLTS DIV to 1 VOLTS DIV 1 MHz to 1 GHz 1 5 1 dc to 800 MHz 1 5 1 1 MHz to 800 MHz 50 pA or less 0 2 div maximum trace shift 1 3 General Information 7A29 TABLE 1 1 CONT Electrical Characteristics Characteristic Performance Requirement POLARITY Balance 0 5 div maximum trace shift IDENTIFY Deflects trace upward 0 2 to 0 4 div o POSITION Range 9 div each direction from graticule center within 1 0 div DC Drift Drift With Ambient Temperature 0 04 div C or less Line Voltage Constant Delay Range Option 4 only At least 1 ns 1 2 GHz 1 1 GHz 1 0 GHz 900 MHz 800 MHz TYPICAL BANDWIDTH 700 MHz 600 MHz 500 MHz 04 05 06 07 08 09 10 MAXIMUM i H CALIBRATED 7 GAIN RELATIVE LOW FREQUENCY SENSITIVITY 2320 11 Figure 1 1 VARIABLE Volts Div contro effe2. 1 2 5 switching sequence All deflection factors within 2 with gain adjusted at 0 1 VOLTS DIV when driven from a 50 Q source At least 2 5 1 See Figure 1 1 for effect on bandwidth Adjustable to at least 3 from nominal at 0 1 V div 1 2 Characteristic General Information 7A29 TABLE 1 1 CONT Electrical Characteristics Frequency Response 10 mV DIV to 1 V DIV High Frequency AC or DC Coupled Low Frequency AC Coupled Maximum Input DC Coupled AC Coupled Input Protection Disconnect Threshold Input Protection Disconnect Time input Impedance Resistance Reflection Coefficient VSWR Except Option 4 DC Coupled AC Coupled VSWR Option 4 DC Coupled AC Coupled input Offset Current VARIABLE VOLTS DIV Balance Performance Requirement When operated in the vertical compartment of the following oscilloscope series 7100 1 GHz 0 to 35 C 7900 500 MHz 0 to 30 C 7800 400 MHz 0 to 35 C 7700 175 MHz 7600 100 MHz 7300 25 MHz NOTE Use of the VARIABLE Vols Div control affects frequency response See Figure 1 1 1 kHz or less from a 50 source 200 Hz or less with a 10X 50 Q probe 10 V rms or 1 watt second pulses not exceeding 50 V peak See Figure 1 2 and Detailed Operating information section 2 100 V additional de component Derate linearly to O V additional at 60 Hz CAUTION RON MN AO ANANA NLN ANAN
3. Volts Div control fully clockwise and notice at least 4 divisions of displayed signal 15 Press the VARIABLE Volts Div control in 16 Set the AC OFF DC switch to the OFF position and notice that no signal is displayed on the crt Operating Instructions 7A29 17 Press the IDENTIFY button Notice that the displayed trace is deflected upward approximately 0 25 division and in oscilloscope mainframes equipped with readout notice that the 7A29 readout display is replaced with the word IDENTIFY 18 Rotate the VOLTS DIV control through each position and note that the 7A29 readout display corresponds with the front panel nomenclature Change the POLARITY switch to INVERT Rotate the VOLTS DIV control through each position Again note that the 7A29 readout display corresponds with the front panel nomenclature Note additionally that a downward pointing arrow appears within the readout display 19 Press and release the VARIABLE Volts Div control Note that a gt symbol appears in the readout display between the downward pointing arrow and the deflection factor information 20 Change the POLARITY switch to UP Note the disappearance of the symbol Press and latch the VARIABLE Volts Div control Note the disappearance of the gt symbol 21 Disconnect the bnc cable from the INPUT connector of the 7A29 22 Connect a 10X readout encoded probe to the INPUT connector and note the corresponding cha
4. With the POSITION control align the display with the center 4 divisions of the graticule area Adjust the GAIN screwdriver adjustment for 4 divisions of display 5 With the POSITION control align the bottom of the displayed signal with the center horizontal graticule line 6 Set the AC OFF DC switch to AC Notice that the displayed signal shifts downward approximately 2 divisions and that the tops of the waveforms are tilted 7 Set the AC OFF DC switch to DC With the POSITION control align the trace with the center and top most graticule lines 8 Set the POLARITY switch to the INVERT position Notice that the displayed signal is now inverted being roughly aligned with the center and bottom graticule lines 9 Set the POLARITY switch to the UP position 10 Rotate the POSITION control fully counterclockwise and notice that the displayed signal can be positioned off the graticule area at the bottom of the crt 11 Set the POLARITY switch to INVERT 12 Rotate the POSITION control fully clockwise and notice that the displayed signal can be positioned off the graticule area at the top of the crt 13 Return the POLARITY switch to the UP position Position the display to the center 4 divisions of the graticule area 14 Press to release the VARIABLE Volts Div control Rotate the VARIABLE Volts Div control fully counterclockwise and notice approximately 1 6 divisions of displayed signal Rotate the VARIABLE
5. environmental characteristics standard and recommended accessories installation and packaging for shipment instructions Section 2 Operating Instructions contains information relative to operating and checking the instrument operation WARNING THE REMAINING PORTIONS OF THIS INSTRUCTION MANUAL CONTAIN SERVIC ING INSTRUCTIONS THESE SERVICING INSTRUCTIONS ARE FOR USE BY QUALIFIED SERVICE PERSONNEL ONLY TO AVOID ELECTRIC SHOCK OR OTHER PERSONAL INJURY DO NOT PERFORM ANY SERVICING OTHER THAN THAT DESCRIBED IN THE OPERATING INSTRUCTIONS UNLESS YOU ARE QUALIFIED TO DO SO Section 3 Theory of Operation contains basic and general circuit analysis that may be useful for servicing or operating the instrument Section 4 Maintenance describes routine and corrective maintenance procedures with detailed instructions for replacing assemblies subassemblies and individual components Section 5 Calibration contains procedures to check the operational performance and electrical characteristics of the instrument Procedures also include methods for adjustment of the instrument to meet specifications Section 6 Instrument Options contains a description of available options and locations of incorporated information for those options Section 7 Replaceable Electrical Parts contains information necessary to order replaceable parts and assemblies related to the electrical functions of the instrument Secti incluc
6. assen wave locatc perfoi portic Sectic infor mech identi INITIAI Da ins op pre rel be This ins etectrica should t exceed inspect transit Operato refer qt Check P damage Office o OPERA To Shu firs The 7AZ can be i series O vertical and low and inse General Information 7A29 front of the oscilloscope and the latch at the bottom left corner of the 7A29 will be in place against the front panel when the 7A29 is fully installed To remove the 7A29 pull on the release latch inscribed with the unit identification 7A29 and the 7A29 will unlatch Continue pulling to slide the 7A29 out of the oscilloscope OPERATING TEMPERATURE The 7A29 can be operated where the ambient air temperature is between 0 and 50 C and can be stored in ambient temperatures from 55 to 75 C After storage at temperatures outside the operating limits allow the chassis temperature to reach a safe operating temperature before applying power PACKAGING FOR SHIPMENT If this instrument is to be shipped for long distances by commercial transportation we recommend that the instrument be packaged in the original manner The carton and packaging material in which your instrument was shipped should be saved for this purpose If this instrument is to be shipped to a Tektronix Service Center for service or repair attach a tag to the instrument showing the following Owner of the instrument with address
7. in excess of 50 V dc turn the AC OFF DC switch to OFF before connecting such a signal to the 7A29 INPUT In the OFF position the ac coupling capacitor is safely precharged to the average dc voltage Figure 1 2 in section 1 shows the maximum rms amplitude which may safely be applied to the 7A29 INPUT Figure 1 2 also corresponds approximately to the rms voltage the 7A29 will accept without automatically disconnecting itself A complex pulse whose rms value is equal to the amount shown in Figure 1 2 is safe if it is also less than 50 V peak For example a 30 V rms sinusoid may be applied for up to 55 ms but a 36 V rms sinusoid may not be applied because the peak voltage exceeds 50 V The 7A29 INPUT may be connected to a 50 V power supply for up to 20 ms because the rms and peak values of the resulting pulse are both 50 V VOLTS DIV SWITCH The amount of deflection produced by a signal is A determined by the signal amplitude the attenuation factor of the probe and the setting of the VOLTS DIV switch Calibrated deflection factors represented by the VOLTS DIV switch apply only 1 When the probe attenuation is X1 or when the input signal is appreciably above 1 kHz with AC coupling the dc blocking capacitor attenuates signals below 1 kHz and 2 when the VARIABLE Volts Div control is in the CAL IN position POLARITY SWITCH The POLARITY switch provides a means of inverting the displayed signal With the POLARITY switch
8. the name of the person at your firm who can be contacted complete instrument type and serial number and a description of the service required H the original packaging is unfit for use or not available package the instrument as follows 1 Obtain a corrugated cardboard carton with at least a 200 pound test strength and dimensions at least six inches larger than the instrument s dimensions 2 Surround the instrument with polyethylene sheeting or equivalent to protect the instrument 3 Allow a 3 inch cushion on all sides by tightly packing dunnage or urethane foam between the carton and the instrument 4 Seal the carton with shipping tape or with an industrial stapler 5 Mark the address of the Tektronix Service Center and your return address in one or more prominent locations on the exterior of the shipping carton SPECIFICATIONS The electrical characteristics listed in Table 1 1 apply when the following conditions are met 1 Adjustment of the instrument must have taken place at an ambient temperature between 20 C and 30 C 2 the instrument must be allowed a 30 minute warm up period and 3 all specifications are valid at an ambient temperature of 0 to 50 C unless otherwise stated TABLE 1 1 Electrical Characteristics Characteristics Performance Requirement Deflection Factor Calibrated Range Attenuator Accuracy GAIN Range From 10 mV div to 1 V div in 7 switch positions using a
9. HECKOUT PROCEDURE The following procedure can be used for incoming inspection to verify proper operation and may also be used by the operator for instrument familiarization Only instrument functions not measurement quantities or specifications are checked tn the procedure therefore a minimum amount of test equipment is required if performing the Checkout Procedure reveals improper performance or instrument malfunction first check the operation of associated equipment then refer to qualified service personnel for repair or adjustment of the instrument NOTE Refer qualified service personnel to the Calibration section of this manual for the procedure to check the Option 4 VARIABLE DELAY control BEFORE YOU BEGIN Refer to the Change Information at the rear of this manual for any modifications which may affect this procedure TEST EQUIPMENT REQUIRED The following test equipment was used in preparing the Operators Checkout Procedure Other test equipment which meets these requirements may be substituted When other equipment is substituted the control settings or setup may need to be altered 1 7000 series oscilloscope mainframe e g 7104 7904 or 7704A 2 7B series time base unit e g 7810 7815 7B80 or 7B85 3 One bnc cable 50 ohm coaxial Tektronix Part 012 0057 01 SETUP PROCEDURE 1 With the 7000 series oscilloscope power switch in the off position connect the oscilloscope to a suitable po
10. Tektronix Inc P O Box 500 Beaverton Oregon 070 2320 00 Product Group 42 97077 Tektronix COMMITTED TO EXCELLENCE PLEASE CHECK FOR CHANGE INFORMATION AT THE REAR OF THIS MANUAL 7A29 AMPLIFIER WITH OPTIONS INSTRUCTION MANUAL Serial Number First Printing APR 1979 Revised JUL 1986 Copyright 1979 Tektronix Inc All rights reserved Contents of this publication may not be reproduced in any form without the written permission of Tektronix Inc Products of Tektronix Inc and its subsidiaries are covered by U S and foreign patents and or pending patents TEKTRONIX TEK SCOPE MOBILE and are registered trademarks of Tektronix Inc TELEQUIPMENT is a registered trademark of Tektronix U K Limited Printed in U S A Specification and price change privileges are reserved INSTRUMENT SERIAL NUMBERS Each instrument has a serial number on a pa el insert tag or stamped on the chassis The first number or letter designates the country of manufacture The last five digits of the serial number are assigned sequentially and are unique to each instrument Those manufactured in the United States have six unique digits The country of manufacture is identified as follows B000000 Tektronix Inc Beaverton Oregon USA 100000 Tektronix Guernsey Ltd Channel Islands 200000 Tektronix United Kingdom Ltd London 300000 Sony Tektronix Japan 700000 Tektronix Holland NV Heerenveen The Netherlands 7A29 Inst
11. ct on bandwidth RATED MAXIMUM RMS INPUT VOLTAGE General Information 7A29 HHP Note The peak input voltage must not exceed 50 V when de wii DURATION Figure 1 2 Maximum rms input voltage TABLE 1 2 Environmental Characteristics Characteristic ee eee RE ET Ee PE O OOOO OOOO OOOO Temperature Calibration Operating Performance Requirement 20 to 30 C 68 to 86 F 0 to 50 C 4320 to 122 F Storage Altitude Operating Storage Tra nsportation To 50 000 feet 55 to 75 C 67 to 167 F To 15 000 feet Qualified under Nationa Safe Transit Committee Test Procedure 1A Category Il 1 5 General Information 7A29 TABLE 1 3 Physical Characteristic Overall Dimensions Net Weight Standard Instrument Option 4 Instrument RECOMMENDED ACCESSORIES The following accessories have been selected from our catalog specifically for your instrument They are listed as a convenience to help you meet your measurement needs For detailed information and prices refer to a Tektronix Products Catalog or contact your local Tektronix Field Representative PROBES P6056 The P6056 is a passive 10X attenuating probe with a bandwidth of de to 3 5 gigahertz and a 500 ohm input resistance for use with 50 ohm inputs 1 6 Characteristics Performance Requirement Compatible with all 7000 series plug in compartments see F
12. dance reducing the voltage to the 7A29 by a precise factor of 2 for 50 ohm calibrators or 10 for 450 ohm Calibrators Thus the 4 V calibrator output of the 7104 and 7904 must be selected for an output voltage of 0 4 volts The vertical deflection should be exactly four divisions If not adjust the front panel GAIN adjustment for exactly four vertical divisions INPUT COUPLING The AC OFF DC switch allows a choice of input coupling methods The type of display desired and the applied signal will determine the coupling to use The DC coupling position can be used for most applications For signals with frequencies below about 1 kHz the DC coupling position is necessary to avoid signal attenuation In the AC coupling position the de component of the signal is blocked by a 2 microfarad capacitor in the input circuit The AC coupling position provides the best display of signals with a dc component much larger than the ac component 2 4 In the OFF position of the input coupling switch the signal path of the amplifier is interrupted so that there is no displayed signal However a signal connected to the INPUT connector will be loaded by approximately 390 kilohms dc or by 195 kilohms ac At extremely high frequencies a small portion of the input signal will still be displayed For example the signal attenuation in the OFF position is about 32 dB at 1 gigahertz The OVERLOAD protection feature of the 7A29 activates
13. ich might damage the plastics used in this instrument Use a nonresidue type of cleaner preferably isopropyl alcohol totally denatured ethyl alcohol or a fluorinated solvent Le trifluorotrichloroethane such as Freon TF cleaner or Spray On 2002 Before using any other type of cleaner consult your Tektronix Service Center or representative DO NOT USE PIN SOCKETS FOR CONNECTION POINTS The spring tension of the pin sockets ensures a good connection between the circuit board and the pin This spring tension can be destroyed by using the pin sockets as a connecting point for spring loaded probe tips alligator clips etc 7529 Instruction 7A29 FEATURES The 7A29 is a wide bandwidth Amplifier Plug In Unit designed primarily for use in vertical compartments of the 7000 Series Oscilloscopes The input is 50 ohm impedance with selectable DC or AC coupling and automatic overload disconnect Seven calibrated deflection factors VARIABLE deflection factor and polarity INVERT selections are provided Readout encoding provides for deflection factor readout including coded probes uncalibrated indication polarity INVERT and IDENTIFY functions A Variable Signal Delay of 0 5 ns is available with the Option 4 instrument GENERAL INFOF INTRODUCTION The Instruction Manual is divided into the following main sections Section 1 General Information contains instrument description electrical specifications
14. igure 1 3 for dimensional drawing Approximately 2 Ibs 8 oz 1 14 kg Approximately 3 tbs 4 oz 1 48 kg EEE EEE MAN AN ANA ar ST Instruction Manual P6057 The P6057 is a passive 100X attenuating probe with a bandwidth of de to 1 4 gigahertz and a 5 kilohm input resistance for use with 50 ohm inputs P6201 The P6201 is an active FET nonattenuating probe with a bandwidth from de to 900 megahertz an input impedance of 100 kilohms and 3 picofarads 1 megohm and 1 5 picofarads with 10X and 100X attenuating heads General Information 7A29 WO zerzi ul 98 y WI 96 9 SLNIOd AINWIXYA LY G3HNSVAN SNOISNAWIO TIVYUH3AO Figure 1 3 7A29 dimensional drawing 7 1 Section 2 7A29 OPERATING INSTRUCTIONS To use the 7A29 effectively the operation and capabilities of the instrument must be known This section describes front panel control functions general information on signal input connections and other subjects that pertain to various measurement applications CONTROLS AND CONNECTORS CAUTION OPN LOLOL LOLS LOLS Before applying any signal in excess of 10 volts to the 7A29 refer to Detailed Operating Information given later in this section of the manual The 7A29 front panel is shown in Figure 2 1 A brief functional description of each control and connector is included in the illustration Refer to Detailed Operating Information for additional information C
15. ime relationship of the two signals By using the VARIABLE DELAY Option 4 the delay times between the two units can be matched to within a few picoseconds thus giving a true time relationship of the signals being viewed For matching delay times of two 7429 units with probes proceed as follows 1 Install the standard 7A29 in the left vertical plug in compartment of the ascilloscope 2 install the 7A29 Option 4 in the right vertical plug in compartment 3 Connect both 7A29 INPUT connectors to one of the signal sources and adjust the time base unit for the fastest convenient sweep available 4 Set the oscilloscope s trigger source switch to Left Vert and verticial mode switch to Alternate 5 Set both 7A29 units to the same deflection factor settings 6 Center both displays vertically 7 Adjust the front panel VARIABLE DELAY knob so that the two displays are superimposed The delay times of both units and the associated cables or probes are now matched 2 5
16. input signa exceeded the safe input level UP A positive going signal at the INPUT connector deflects the crt display upward INVERT A positive going signa at the INPUT connector defiects the crt display downward POLARITY Switch Provides a means of inverting the display 4 VARIABLE Controi Provides continuously variable defiection factors between settings of the VOLTS DIV switch VOLTS DIV Switch Selects calibrated deflection factors from 10 mV Div to 1 V Div 7 steps in a 1 2 5 sequence IDENTIFY Switch Deflects the trace about 0 2 division for trace identification In instruments with readout also replaces readout with the word IDENTIFY O POSITION Control Controls the vertical position of the trace GAIN Controf Screwdriver adjustment permits calibration of deflection factor Option 4 VARIABLE DELAY Controtj Detays the signal up to and 500 picoseconds by using a calibrated 10 turn dial deleted on the standard 7A29 10 eur Connector Provides a means for connecting a signal Figure 2 1 Front panel controls connectors and indicators 2 2 5 Set the oscilloscope s power switch on and allow at least 20 minutes warmup AMPLIFIER FUNCTIONS 1 Connect a bnc cable from the oscilloscope s calibrator output connector to the 7A29 INPUT connector 2 Rotate the B intensity control clockwise until the trace is just visible 3 Set the 7A29 AC OFF DC switch to DC 4
17. nge in the defiection factor of the displayed readout Repeat with 100X probe NOTE Readout encoding is accomplished by connecting a resistance from the outer ring of the 7A29 INPUT connector to ground The following gives the resistance value necessary to simulate a probe and may be used in place of an actual probe Function Resistance ME SN eed et eee Ya PN Na Sa Ka Open circuit O an 11 KO within 596 ADO Pee enam Wiser 6 2 kQ within 5 IDENTIFY nata aan knpa ale nb ohms 23 This completes the Operators Checkout Procedure 2 3 Operating Instructions 7A29 DETAILED OPERATING INFORMATION PROBES Probes recommended for use with the 7A29 are the P6056 10X or P6057 100X Both probes are compatible with 50 ohm systems and will allow good frequency response These probes also contain trace IDENTIFY and readout encoding functions If the P6201 Probe is used a one megohm input impedance may be achieved with some loss in bandwidth Consult your local Tektronix Field Engineer or Representative for further information VERTICAL GAIN CHECK AND ADJUSTMENT To check the gain of the 7A29 set the VOLTS DIV switch to 0 1 Y and connect a 0 4 V 1 kHz signal from the oscilloscope mainframe calibrator to the 7429 INPUT connector NOTE Oscilloscope calibrators typically have an output impedance of either 50 Q or 450 DO The 50 ohm input impedance of the 7A29 forms a voltage divider with the calibrator output impe
18. ruction SERVICE SAFETY INFORMATION FOR QUALIFIED SERVICE PERSONNEL ONLY The following are safety precautions which appear in the service information sections of this manual This Service Safety information is in addition to the Operators Safety Information given previously WARNING DO NOT SERVICE ALONE Do not attempt internal service or adjustment unless another person capable of rendering first aid and resuscitation is present DISCONNECT INSTRUMENT POWER To avoid electrical shock hazard disconnect the instrument from the power source before removing protective panels soldering or replacing components SL LB Sa EL DEIS CAUTION PON LON OLN MA EN INS AVOID EXCESSIVE MOISTURE Circuit boards and components must be dry before applying power to prevent damage from electrical arcing Pins 2 and 3 of U246 and U266 are especially sensitive to moisture Excessive moisture in this area of the circuit board will cause the trace to wander irregularly and possibly leave the screen area EXERCISE CARE WHEN SOLDERING The Main Amplifier circuit board is a multilayer type with two identical conductive paths laminated between the top and bottom board layers All soldering on this board should be done with care to prevent breaking the connections to the center conductors Only experienced maintenance personnel should attempt repair of any circuit board USE PROPER CLEANING AGENTS Avoid the use of chemical cleaning agents wh
19. set to UP a positive going signal at the INPUT produces an upward deflection on the crt display With the POLARITY switch set to INVERT a positive going signal will produce a downward deflection on the crt display TRACE IDENTIFICATION AND READOUT FUNCTIONS When the IDENTIFY button is pressed the trace is deflected upward about 0 3 divisions to identify the 7A29 trace This feature is particularly useful when multiple traces are dis played on the cri In oscilloscope mainframes with readout the IDENTIFY button also replaces the 7A29 s deflection factor readout display with the word IDENTIFY The 7A29 is equipped with probe encoding circuitry that when used with a coded probe corrects the deflection factor readout VARIABLE DELAY OPTION 4 The option VARIABLE DELAY line provides a means for delaying the signal applied to the INPUT connector up to 500 picoseconds relative to another 7A29 a 7A19 or 7A19 Option 4 When the Option 4 instrument is used with a standard 7A29 which has a fixed delay the REV JUN 1981 Operating Instructions 7A29 VARIABLE DELAY control can be used to match the signal delay time of both units MATCHING DELAY TIMES USING TWO 7A29 UNITS ONE HAVING VARIABLE DELAY OPTION 4 In some applications it is necessary to view the time relationship of two signals one with respect to the other With high speed signals the delay times of the probes and amplifiers can distort the true t
20. wer source 2 Instal the 7A29 in the left vertical compartment 3 Install the 7B series time base unit in the B horizontal compartment 4 Set the front panel controls as follows 7A29 AMPLIFIER VOLTS DIV weten zen 0 1 V VARIABLE Volts Div 22 CAL IN POSITIONS as ee ee te Midrange POLARITY san este AN en UP AC pre DO san bana maa Rina ates OFF Time Base Unit TANG DIV Gis dnb cctv a gn pute Mune Re PAN ARE 1 ms POSO os Na NN Pan ee Midrange O en PAMA PANRB Le Ra Xt Triggering Mode a Sate AN Gade E anneal wee pats Auto External Trigger In nee In Combi een eig AC SOUL UU ma Internal Oscilloscope Vertical Mole sure Oia NE tale eer Left Horizontal Mode ua ta rest B B Trigger SOUMGs nie Vert Mode Calibrator unten Rasen 4 Y A and B Intensity Counterciockwise 2 1 Operating Instructions 7A29 BIENEN POSITION VARIABLE CAL IN VOLTS DIV VARIABLE DELAY RANGE G bas 0 01 Y MAXIMUM INPUT TEV RMS 50V PEAK Tektronix AMPLIFIER AC OFF DC Switch Selects signal input coupling mode AC The ac component of the signal is coupled to the amplifier input while the de component is blocked OFF Disconnects input signal precharges input coupling capacitor and resets input protection system when OVERLOAD tight is on DC Both ac and de components of the signal are coupled to the amplifier input 2 overtoan Indicator When on indicates that
21. when a signal capable of causing damage to 7A29 internal circuitry is applied to the INPUT connector To reset the 7A29 turn the AC OFF DC switch to the OFF position and remove the cause of overloading The 7A29 is then ready for normal operation The 7A29 is capable of withstanding short term overloads in excess of its continuous rating of 10 V rms Thus it is possible to apply 50 V peak the same as 50 V rms for a single pulse for 20 ms or a 20 V rms signal for 125 ms The 7A29 integrates the rms input power and disconnects the signal before damage can occur Generally speaking the 7A29 will protect itself from excessive damaging signals however there are exceptions Continuous wave or pulsed radio frequency signals above 100 MHz are not sensed by the input protection circuitry and may cause damage to the input attenuator if in excess of the 10 V rms 50 V peak rating The relay contacts which disconnect the 7A29 from excessive voltages may themselves be damaged by arcing lf the contacts open with a signal greater than 50 V applied to the INPUT the contacts may be permanently damaged The ac coupling capacitor used in the AC position of the AC OFF DC switch is rated at 100 V dc Since the input protection circuitry is located after the ac coupling Capacitor application of up to 100 V dc to the INPUT is possible in the AC coupled mode However in order to avoid a fast rise pulse being sent to the 7A29 from a signal
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