Tektronix 7A22 Instruction Manual Download Page 71

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Summary of Contents for 7A22

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Page 2: ...price change privileges are reserved INSTRUMENT SERIAL NUMBERS Each instrument has a serial number on a panel insert tag or stamped on the chassis The first number or letter designates the country of...

Page 3: ...formation 2 4 Trace Drift 2 4 Input Gate Current 2 4 Section 2 OPERATING INSTRUCTIONS COllt Voltage Measurement Page 2 4 Signal Input Connectors 2 4 High Input Impedance 2 5 Display Polarity 2 5 Defle...

Page 4: ...r 4 1 Visual Inspection 4 1 Transistor Checks 4 1 Calibration 4 1 Corrective Maintenance 4 1 General 4 1 Obtaining Replacement Parts 4 2 SECTION 4 MAINTENANCE cont Page Special Parts 4 2 Soldering Tec...

Page 5: ...x of Electrical Parts List C141 Cross Neutralization 5 7 Electrical Parts List C115 X1 Input Atten Time Constant 5 7 SECTION 7 DIAGRAMS AND MECHANICAL C215 X1 Input Atten Time PARTS ILLUSTRATIONS Cons...

Page 6: ...Fig 1 1 Type 7A22 Differential Amplifier Type 7A22...

Page 7: ...DIV Gain Ratio Accuracy Within 2 with GAIN adjusted at 1mV div VAR CAL IN Range Continuously variable extends de flection factor to at least 2 5V div GAIN Permits adjustment of deflection factor at 1m...

Page 8: ...I a n 3 ii1 Jl c I 0 a I I a 5 III n 0 3 3 0 I 3 0 a a I Q I III it Verification Points I CMRR...

Page 9: ..._ _ _ _ _ _ _ _ _ _ _ Displayed Noise Tan 1 6 p V or 0 1 Div whichever is getially Measured greater 1 MHz HF 3 dB POINT source resistance 25n or less DC Drift Drift with Time Ambi ent Temperature and...

Page 10: ...set to the 1 mV position The control that vertically positions the trace or display Momentary contact push button switch concentric with POSITION Will cause the trace representing the output of the Ty...

Page 11: ...east one hour 5 Adjust the Intensity control for normal viewing of the trace The trace should appear near the graticule center 6 Using the POSITION control position the trace 2 divi sions below gratic...

Page 12: ...ith the POSI TION control Co With the VAR CAL IN in the out position rotate the VARIABLE control from stop to stop Check for no move ment of trace d Adjust R425 for no movement of trace as the VARI AB...

Page 13: ...nput coupling capaci tor acquires a charge due to dielectric polarization and acts as a low voltage high impedance voltage source with a very slowly decaying output voltage This can offset sub sequent...

Page 14: ...flection produced by a signal is determined by the signal amplitude the Otlenuotion foetor of the probe the setting 01 the VOLTS DIV switch and the selling of the VARIABLE control The calibrated delle...

Page 15: ...Worst case degradation due to source resistance_ I f I i I I I 10 n r r f l 1 I I I I I Rs t DC r I r r t i f f I I I I I I t I 3 r t o With high impedance 0 provision I 7 r 60 in use I Hz 3 o 7 i i D...

Page 16: ...esistance v v v v Vs I 100 lk J I 1100 I r C 1 I I I v I 1 0 VI Vl VOl ts DiV error 1 1 1 Mil Input Rs I I y c 1 Mfl lnput Bandwidth I HF 3 dB POINT at 1 MHz No external C I i High Impedance Input i 1...

Page 17: ...ructions Type 7A22 1 f M M C C C 0 0 0 0 0 C C N I C OJ I dB reI 100 kHz C I I C Xl I N r 0 N t C N J N c o o Fig 2 5 7A22 FREQUENCY RESPONSE as a function of LF 3 dB POINT SETTING HF 3 dB POINT at 1...

Page 18: ...Operating Instructions Type 7A22 c c I I dB rei 10 Hz C M I Fig 2 6 7A22 FREQUENCY RESPONSE as a function of HF _ 3 dB POINT settings IF 3 dB POINT of DC J t g J t C J t r g J c 2 9...

Page 19: ...s indicated by the common mode rejection ratio CMRR This ratio is at least 100 000 1 at the input connectors for the lower deflection factors 1 0 V to 1 0 mV per division when signals between DC and 1...

Page 20: ...that is switched into the amplifier circuit for the various VOLTS DIV switch positions TABLE 2 1 VOLTS DIV setting OFFSET RANGE ATTENUATOR in c c oc c _ _ _ c _ _ _ _ _ cc oc cc _ _ _ _ __ _ i _ C _...

Page 21: ...Type 7A22 INPUT OVERDRIVE indica tor provides an indication that such a signal is present by lighting before the gain calibration changes by 1 If the INPUT OVERDRIVE lamp turns on there are two pos si...

Page 22: ...factor at the tip of the probe with the larger division ratio 100X REV B AUG 1974 Operating Instructions Type 7A22 TABLE 2 2 Trace Idenlify With the oscilloscope turned on and a sweep displayed on th...

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Page 24: ...nly the output amplifier gain switching is used to set the deflec tion factor 1 Preamp From the input attenuators the signal is coupled to the preamp The preamp consists of two identical feedback am p...

Page 25: ...ARIABLE VOLTSjDIV are provided in the stage following the HF 3 dB POINT se lector Overall amplifier gain is adjusted in the signal output stage of the Output Amplifier by adjusting the common emit ter...

Page 26: ...oltage can also be obtained by passing io through the load resistor R3 The overall voltage gain is then Vo h h I I R 3 V w IC IS approximate y equa to R Differential Configuration If the lower end of...

Page 27: ...rease a temperature sensitive input current balancing network is included using thermistors as the sensing elements As the voltage across R111 and R211 increases due to in creasing FEr gate current at...

Page 28: ...can be obtained Floating Power Supply The supply voltages for the X 15 preamp are obtained from a chain of Zener diode shunt regulators VR305 VR320 and VR325 connected in series Current is supplied b...

Page 29: ...o Vcm ie follows Vcm and that no changes in voltage or current levels occur any where within the amplifier as a result of Vcm except for Q153 and Q253 drain to gate voltage Thus the only mis match of...

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Page 31: ...ontrol A capacitor filters out Zener noise from the reference voltage The feedback amplifiers A and B are composed of Q264A Q273 and Q264B Q283 respectively with the reference in put applied to the em...

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Page 33: ...lean overdrive recovery The AC STEP ATTEN BAL adjustment R505 in series with the source of 0404B develops a small adjustable voltage which removes any initial unbalance in the gate to source voltages...

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Page 35: ...yed read out will give the correct deflection factor from the probe tip for a single probe or two probes having the same attenuation factor whereas the VOLTS DIV knob on the plug in will dis play only...

Page 36: ...unit should be inspected occasionally for such defects as poor connections broken or damaged circuit boards im properly seated transistors and heat damaged parts The remedy for most visible defects is...

Page 37: ...cations These and most 4 2 mechanical parts should be ordered through your Tektronix Field Engineer or Field Office See Parts Ordering Informa tion and Special Notes and Symbols on the page immedi ate...

Page 38: ...2 j Remove the two screws securing the AC GND DC switch to the front sub panel and remove the switch k Replace by reversing the above procedure 2 AC GND DC INPUT Switch a Perform step 1 parts a throug...

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