Model 461A/462A Wideband Amplifier Operating and Service Manual
Contents
1. 1 KHz to 150 MHz when operating into a 50 ohm resis tive load 600 KHz reference Gain at 500 KHz 40 db 20 5 db or 20 db 1 0 db selected by front panel switch Output is inverted with respect to input ve Tt Output 0 5 20 56Hts rms into 50 ohm resistive load Distortion Less than 5 at maximum output and rated load MODEL 462A Pulse Response Rise and Fall Time Less than 4 nano seconds Over and Undershoot Less than 5 Gain 40 db or 20 db selected by front panel switch Output is inverted with respect to input 01358 3 INFORMATION 1 3 Since the Models 461A and 462A are nearly iden tical this manual will discuss the instruments interms of the Model 461A The Model 462A will be mentioned only when its operation differs from that of the Model 461A 1 4 ACCESSORIES AVAILABLE 1 5 The hp 11048A 50 ohm feedthrough termi nation is an available accessory that is connected at the output of the Model 461A The feedthrough termi nation should be used to ensure that the Model 4614 is operating into its rated impedance in the event the instrument is connected to a device with an im pedance greater than 50 ohms Specifications Pulse Duration for 10 Droop 30 usec Output 1 volt peak to peak into 50 ohm load Delay Nominally 12 14 nanoseconds GENERAL 461A and 462A Maximum Input 1 volt rms or 2 v p to p Maximum DC Input 2 volts Overload Recovery Less than 1 psec for 10 ti2. POWER SUPPLY 4 8 The power supply generates 15 volts and 15 volts bias supply to the amplifiers Breakdown diode A2CR3 establishes a 15 volt reference Control transis tor A2Q2 detects differences between the reference voltage and the supply output and its output controls the series regulator Q1 EMITTER FOLLOWER Q4 Q8 Q9 SERIES REGULATED POWER SUPPLY Qal Q3 Simplified Block Diagram 4614 462A B 9 4 1 Section V Models 461A 462A Table 5 1 Table 5 1 Test Equipment Required Instrument Critical Use Recommended Type Specifications Model Wide Range Os Output 3 v Gain Check hp Model 200SR Wide cillator Impedance 50 ohms Range Oscillator Freq Range 5 Hz 500 KHz Distortion less than 0 5 Freq Range 500 KHz to 10 MHz sponse Test Freq Response Flat within 0 5 quency Response Test Set 1 5 500 KHz to 10 MHz Set Logarithmic Accuracy 1 at full scale Gain Check hp Model 400L Loga Vacuum Tube Freq Range 10 Hz to 500 KHz rithmic Vacuum Tube Voltmeter DB Range 60 to 10 db Voltmeter Attenuator Attenuation 40 db Frequency Response Weinschel 50 408 Accuracy 40 1 db and Gain Check Freq Range 1 KHz to 150 MHz Attenuator Attenuation 120 db in 10 db steps Frequency Response hp Model 355D VHF Freq Range 1 KHz to 150 MHz and Gain Check Coaxial Attenuator Overall Accuracy 1 5 db Impedance 50 ohms Freq Range 20 Hz to 500 KHz Sensitivity Measure 5 distortion Acc
3. The Model 461A will operate within specifications only when its output is terminated in 50 ohms 3 3 FRONT AND REAR PANEL DESCRIPTION 3 4 Figure 3 1 describes the function of all the con trols and indicators on both the front and rear panel 3 5 OPERATING INSTRUCTIONS 3 6 Figure 3 2 contains the operating instructions for the Model 461A Each instruction is keyed to a drawing of the front panel Section HI Paragraphs 3 1 to 3 10 and Figure 3 2 INSTRUCTIONS 3 7 IMPEDANCE MATCHING 3 8 Both the input impedance and the output impe dance of the Model 461A are 50 ohms The Model 461A output must be connected to a 50 Q load if it is to operate within specifications If the input impedance of the load isnot 50 2 a terminating impedance of 50 Q must be connected across the Model 461A output The hp Model 11048A 50 2 Feedthrough Termination is recommended for this purpose The Model 11048A may be easily connected in series with the Model 461A output 3 9 CASCADING AMPLIFIERS 3 10 The Model 461A will amplify small signals in the 5to 50 millivolt range to an amplitude of 0 5 volts withminimum distortion Shouldlarger output signals be desired the Model 461A can be cascaded with other amplifiers such as the hp Models 460A and 460B Typical set ups cascading the Model 461A and Models 460A and 460B are shown in Figures 3 3 and 3 4 SIGNAL SOURCE AUAIAS2A B 0825 Connect the 1 KHz to 150
4. 01358 3 OPERATING AND SERVICE MANUAL HP PART NO 00461 90002 MODEL 461A 462A WIDEBAND AMPLIFIER SERIALS PREFIXED 606 461A 551 462A Appendix C Manual Backdating Changes adapts manual to Serials Prefixed 418 346 461A 421 414 and 347 462A Copyright Hewlett Packard Company 1963 P O Box 301 Loveland Colorado 80537 U S A Printed AUG 1966 Section I Models 461A 462A Figure 1 1 4614 AMPLE mom qu om Model 461A Wide Band Amplifier ame P senate perans GAIN BT 20 Model 4624 we Wide Band Amplifier men Figure 1 1 Hewlett Packard Model 461A 462A Wideband Amplifier 1 0 01358 1 Models 461A 462A Section I Paragraphs 1 1 to 1 5 and Table 1 1 SECTION I GENERAL 1 1 GENERAL INFORMATION 1 2 The hp Models 461A and 462A Wide Band Am plifiers can faithfully amplify both sinusoidal and com plex signals inthe 1 KHz to 150 MHz range The Model 461A is best suited for sinusoidal inputs and the Model 462A is designed for complex and pulse inputs The Model 461A frequency response is 1 db from 1 KHz to 150 MHz The Model 462A rise and fall times are less than 4 nanoseconds Either 40 db or 20 db gain can be selected with the front panel GAIN DB switch The Models 461A and 462A are shown in Figure 1 1 The specifications of both instruments are given in Table 1 1 Table 1 1 MODEL 461A Frequency Range 1 KHz to 150 MHz Frequency Response 1 db
5. MHz frequency source to the input of the Model 461A Connect the output of the Model 461A to a 50 ohmioad The instrument will be within specifi cations only if connected to a 50 ohm load Set Power and Gain Switch to the desired gain setting 20 or 40 db hp 461A WIDE BAND AMPLIFIER DO NOT APPLY MORE THAN 1 VAC OR 2 VDC TO INPUT TERMINALS VOLTAGE LEVEL AT OUTPUT MUST NOT EXCEED 6 VOLTS DC OR 0 6 VOLTS DC NOTE The maximum output voltage obtainable from the Model 461A is 0 5 volts rms i Volt P P for Model 462A Thus the maximum input voltage that can be ap plied without distortion is 50 mv on the 20db range and 5 mv onthe 40 db range Figure 3 2 Operating Instructions 01358 2 3 1 Section IH Models 461A 462A Figures 3 3 and 3 4 SIGNAL SOURCE DMODEL 461A MODEL 460AR WIDE BAND WIDE BAND AMPLIFIER AMPLIFIER input QS output Q O 461A 4624 B 6 SVOLTS P P Figure 3 3 Cascading Amplifier SIGNAL SOURCE MODEL 460AR MODEL 460BR MODEL 461A WIDE BAND AMPLIFIER WIDE BAND AMPLIFIER WIDE BAND AMPLIFIER INPUT OUTPI Peo 451A7462A B AN LIMVP P ASUI Toom P P Das A I VOLT P P 5 VOLTS P P Figure 3 4 Cascading Amplifier 3 2 01358 2 od Models 4614 4624 Section IV Paragraphs 4 1 to 4 8 SECTION IV THEORY OF 4 1 GENERAL DESCRIPTION 4 2 The Models 461A and 462A Amplifiers are es se
6. mes overload Equivalent Input Noise Level Less than 40 microvolts in 40 db position Input Impedance 50 ohms nominal Power Supply 115 or 230 v 2109 50 to 1000 hertz 95 watts Dimensions 3 14 32 8 7 em wide x 11 27 9 cm long Weight Net 4 lbs 1 8 Kg Shipping 6 lbs 2 7 Kg Accessory Furnished Detachable Power Cord Accessory Available hp 11048A 50 ohm through termination 1 1 Section HI Figure 3 1 Models 4614 462A AGIA AMPLIFIER HEWLETT PACKARD GAIN DB IRC ISOMC 4814 482A 8 3 GAIN DB switch Applies primary power and AC POWER connector Connects primary power selects gain to the instrument 50 Q INPUT connector Connects input signal to the instrument DO NOT APPLY MORE THAN 1 VAC OR 2 VDC TO INPUT LINE VOLTAGE Selects either 115 volts ac or 280 volts ac primary power 50 2 OUTPUT connector Connects amplified outputtoload Output must be terminated in 50 Q VOLTAGE LEVELAT OUTPUT MUST NOT Fuseholder Contains a 1 4 ampere fast blow EXCEED 6 VOLTS DC OR 0 6 VOLTS DC fuse for both 115 and 230 volt operation Figure 3 1 3 0 Front and Rear Panel Description 01358 1 Models 461A 462A SECTION OPERATING 3 1 INTRODUCTION 3 2 The Model 461A canbe used to faithfully amplify signals inthe 1 KHz to 150 MHz range Gain settings of 20db or 40 db may be selected with the front panel GAIN DB switch
7. ntially identical In the Model 462A some of the component values are changed slightly to improve its pulse response In this section both instruments will be presented in terms of the Model 461A 4 3 Figure 4 1 shows a simplified block diagram of the Model 461A The amplifier isafive stage stagger tuned cascaded amplifier with emitter follower input and output stages The gain is switched from 40 db to20 db by attenuating the input by 20 db The power supply is a conventional series regulated supply with 15 volt and 15 volt outputs 4 4 AMPLIFIER CIRCUITS 4 5 Figure 5 13 shows the schematic diagram of the Model 461A A3Q3 is the input emitter follower matching the 50 Q input impedance to the input impe dance of the amplifier Transistors A8Q4 through EMITTER FOLLOWER Q3 ATTENUATOR Al PRIMARY POWER amp GAIN SWITCH si 83 PRIMARY POWER Figure 4 1 01358 2 AMPLIFIERS OPERATION A8Q8 constitute a five stage RC coupled cascaded amplifier Each stage has a gain of 8 db giving the amplifier a total gain of 40 db 4 6 Each stage has an LR feedback circuit with an adjustable inductor The feedback circuit in each stage controls the overall gain of the amplifier ata different frequency sothe amplifier must be stagger tuned There is some interaction between the stages at certain frequencies A8Q9 is the output emitter follower and it matches the amplifier output to a 50 Q output impedance 4 7
8. onse Check Sensitivity 0 1 v em to 1 v em Bandwidth 50 MHz to 1 GHz Sensitivity 200 mv em to 5 v em Pulse Response Check and Calibration Impedance 50 ohms Leading and Trailing Edge lt 1 nsec Overshoot and Ringing lt 5 peak Corner Rounding Amplitude lt 95 of pulse amplitude Pulse Width 30 nsec Pulse Generator Pulse Generator Pulse Width 1 psec Pulse Overload hp Model 212A Pulse Pulse Amplitude 0 5 v p p Recovery Check Generator Square Wave Pulse Width 30 psec Pulse Decay Check hp Model 211A Square Generator Pulse Amplitude 0 01 v p p Wave Generator 5 0 01358 2
9. uracy 3 RF Millivolt Freq Range 500 KHz to 150 MHz Frequency Response hp Model 411A RF meter Accuracy 6 full scale Noise Check Millivoltmeter DB Range 30 db to 10 db Multimeter Accuracy 1 full scale Troubleshooting and hp Model 412A DC Input Resistance 200 M Q Power Supply Checks Voltmeter Ohmmeter Signal Generator Ammeter Power Meter High Frequency Check hp Model 608C D VHF Signal Generator Oscilloscope High Frequency Check hp Model 431A B Oscilloscope Power Meter with hp 478A Thermistor Mount High Frequency Oscilloscope Frequency Response hp Model 739A Fre Check Frequency Re hp Model 331A Distor tion Analyzer Distortion Distortion Check Analyzer Freq Range 10 MHz 150 MHz Output 0 5 v Impedance 50 ohms Power Range 30 dbm to 10 dbm Accuracy 3 full scale hp Model 122A Dual Track 200 Ke Oscil loscope or hp Model 175 Oscilloscope hp 1750A and 1780A Plug in units hp Model 175A Oscil loscope hp Model 185B 100 Mce Oscilloscope with hp 187B Dual Trace Amplifier Pulse Response Check hp Model 215 Pulse and Calibration Generator Bandwidth De to 200 KHz Sensitivity 10 mv em to 10 v em Type dual trace Frequency Response Calibration Bandwidth 1 KHz to 50 MHz Pulse Resp
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