HP 467A Operating and Service Manual
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HP 467A is a versatile device that offers both power amplification and power supply capabilities. As an amplifier, it provides a wide bandwidth with low drift from DC to 1 MHz, making it suitable for various applications requiring a stable power source. With multiple feedback techniques and high-quality components, it achieves low distortion (<0.01%) and high gain accuracy (0.3%). The gain can be varied between 1 and 10 using fixed gain steps or a variable gain control for precise adjustment. The output capability extends beyond 20 volts peak and 0.
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OPERATING AND SERVICE MANUAL {HP PART NO. 00467-90003) MODEL 467A POWER AMPLIFIER/SUPPLY SERIALS PREFIXED: 444. Copyright Hewlett-Packard Company 1965 Р.О. Вох 301, Loveland, Colorado, 80537 U.S. A, Printed AUG 1969 Model 467A Section 1 SECTION I GENERAL 1-1, DESCRIPTION. 1-2, The solid state 467A Power Amplifier/Supply is a 10 watt peak power amplifier and -20 £o +20 voit dc power supply. The power amplifier has a wide bandwidth with low dec drift from de to 1 MHz offering wide applications wherever a power source is re- quired. Low distortion (<0, 01%), low drift and 0.3% gain accuracy are obtained with high quality compo- nents and muitiple feedback techniques. The gain of the amplifier may be varied between one and ten by a front panel switch which provides fixed gain steps accurate to +0.3%, A variable gain control enables the user to set the gain anywhere between zero and ten witha resolution of better than 0.1% of full output. Table 1-1 gives the specifications for the 467A Power Amplifier/Supply. 1-3. QUTPUT CAPABILITY. 1-4. An output greater than 20 volts peak and 0.5 ampere peak is available from dc up to 1 MHz. The amplifier is protected at all times from short cir- cuits. The input circuit of the 467A is protected against damage from voltages up to 200 volts p-p, INFORMATION Input and output connectors are provided at the front and rear of the instrument. The amplifier is a three terminal device isolated from chassis and may be floated up to 200 volts dc above chassis ground. 1-5, POWER SUPPLY. 1-06. A front panel switch converts the amplifier to a power supply that delivers +20 volts de at currents up to 0.5 ampere. The output level is controlled by a potentiometer which permits voltages to be set with resolution of 0,1% of full scale. Full scale ranges of £1,+2,+4, +10, and £20 volis are selected by the front panel range switch. 1-7. INSTRUMENT IDENTIFICATION. 1-8. Hewlett-Packarduses a two-section eight-digit serial number (000-00000). If the first three digits of the serial number on your instrument do not agree with those on the title page of this manual, change sheets supplied withthe manual will define differences between your instrument andthe Mode! 467A described in this manual. il Mode! 467A Section II SECTION II INSTALLATION 2-1. INSPECTION. 2-2. Upon receipt, unpack and inspect the instrument for mechanical and electrical damage. Mechanical inspection includes visually checking the instrument for scratched and warped surfaces, damaged control knobs, switches, and indicators, and signs of weather exposure, The electrical inspection involves checking instrument operationagainst specification values given in Table 1-1, Refer to Paragraph 5-5, NOTE in case of mechanical damage, file a claim with the carrier im- mediately. Tf an electrical mai- function occurs, refer to the war- ranty page in the front of this manual, 2-3. INSTALLATION. 2-4. The Model 467A is a submodular unit that can be mounted on a bench, or in a rack or cabinet. It is shipped with plastic feet and tilt stand in place, ready for bench use. When used as a single submodule, it is utilized as a bench unit only. When used in com- bination with other submodule units, a rack adapter frame or combining case is available for rack or cabinet mounting. The instrument should be installed where ambient temperature does not exceed 50°C (12295. | 2-5. POWER REQUIREMENTS. 2-6. The Model 467A can be operated from a 115 or 230 ac volt £10 source at 50 to 400. Hz, Power con- nections are made by plugging the power cable (sup- plied with the instrument) into the AC POWER male connector at the rear of the unit and the appropriate power receptacle. An 0.8 ampere slow-blow fuse is used for 115 and 230 volt operation. ÉCAUTIONS BEFORE PLUGGING POWER CABLEINTO THE RECEPTACLE, DETERMINE THAT THE LINE VOLTAGE SWITCH ON THE REAR PANEL IS SET PROPERLY TO ACCEPT THAT VOLTAGE (115 OR 230). 2-7. THREE-CONDUCTOR POWER CABLE. 2-8. All Hewlett-Packard instruments are equipped with a three-conductor power cable, which complies with the recommendations of the National Electrical Manufacturer's Association (NEMA) for rack and cabinet grounding, The offset pin on the cable is the ground connector. NOTE When operating from a two-con- tactoutlet, the grounding feature canbe maintained by using a three- pronged adapter and connecting the green pigtail on the adapter to ground. 2-9. REPACKAGING FOR SHIPMENT. 2-10. Thefollowing paragraphs contain a general guide for repackaging of the instrument for shipment. Re- fer to Paragraph 2-11 if the original container is to be used; 2-12 if it is not. If you have any questions, contact your local -hp- Sales and Service Office. (See Appendix B for office locations.) NOTE if the instrument is to be shipped to Hewlett-Packard for service or repair, attach a tag to the in- strument identifying the owner and indicating the service or repair to be accomplished: include the model number and full serial number of the instrument. In any correspondence, identify the Instrument by model number, serial number, and serial number prefix, 2-11. If original container is to be used, proceed as follows: a. Place instrument in original container if avail- able. H original container is not available, one canbe purchased from your nearest -hp- Sales and Service Office. b. Ensure that container is well sealed with strong tape or metal bands. 2-12. If original container is not to be used, proceed as follows: a. Wrap instrument in heavy paper or plastic before placing in an inner container. b. Place packing material around all sides of instrument and protect panel face with card- board strips. ¢. Place instrument and inner container in a heavy carton or wooden box and seal with strong tape or metal bands. d. Mark shipping container with "DELICATE INSTRUMENT, " "FRAGILE" etc, 2-1 Model 467A 3-7. AMPLIFIER OPERATING INSTRUCTIONS. a. Set the AMPLIFIER/SUPPLY control fo the AMPLIFIER position, selecting the desired gain setting (VAR., X1, X2, X5, or X10). b. Set the LINE switch to ON. NOTE To assure maximum stability, allow the instrument to warm up for 30 minutes, Section III SECTION 11 OPERATING INSTRUCTIONS 3-1. GENERAL. ¢. Connect DC Voltmeter (-hp- Model 412A) to the | 467A OUTPUT terminals; adjust the ZERO 3-2. The Model 467A Power Amplifier/Supply canbe control fo obtain a zero de output. operated as a power amplifier or a power supply. Controls on the front panel provide: (1) selection of either operating mode and (2) selection of fixed or d. Connect 467A OUTPUT terminals to the de- variable amplifier gain and power supply ranges. plied o which the amplified signal is being ap- 3-3. DESCRIPTION OF CONTROLS, | e. Connect the signal to be amplified to the 467A 3-4, Figure 3-1 gives the description and function INPUT terminals. of the 467A controls, indicators and connectors, 3-8. POWERSUPPLY OPERATING INSTRUCTIONS. 3-5. OPERATING INSTRUCTIONS. 3-6. Whenoperated as a power amplifier (non-invert- a Connect the 467A OUTPUT terminals to the de- ing}, the Model 467A has four calibrated gain factors vicetowhich the power supply isbeing applied. (AMPLIFIER: Xl, X2, X5, and X10) and provides a maximum output power of 10 watts peak for input fre- b. Set 467A AMPLIFIER/SUPPLY control in the quencies between de and | MHz. Accuracy of +0.3% SUPPLY range to the desired voltage setting from dc to 10 kHz ig obtained when operating into a (+1, +2, +4, +10, ог +20). load of 40 ohms or greater. As apower supply (regu- lated), the instrument can be operated in five ranges a of plus or minus output voltages (SUPPLY: +1, +2, с. Set the LINE switch to ON. +4, +10, and +20). The amplifier gain, or the + de output can be varied with the VAR. GAIN/VOLTS ADJ. NOTE control. The input and cuiput terminals are de isolated from earth ground. Connection of a grounding strap To assure maximum stabilization, between the power line ground (44) and (4) terminals allow the instrument to warm up references boththe INPUT and OUTPUT (4) terminals for 30 minutes. to earth ground. d. Usingthe VAR. GAIN VOLTS ADJ. control, ad- just the voltage to the desired level. NOTE The VAR, GAIN VOLTS ADJ, con» trol is used for both coarse and fine adjustments, Coarse adjust is made after either limit of the fine adjust is reached, Full CCW position produces maximum negative voltage. FuliCW position produces maximum positive voltage, 3-1 Section HI Model 467A HEWLETT - PACKARD VOLTS ADJ, a. > бр 467A POWER AMPLIFIER \ 467A-R- 0300 | LINE ON: switches voitage on; indicator glows when ac line voitage is ON, AMPLIFIER/SUPPLY: selects power ampli- fier or power supply mode of operation for the instrument. AMPLIFIER (X1, X2, X5, X10): selects the fixed step gain factor. AMPLIFIER (VAR. ): operates in conjunction with VAR.GAIN to provide variable control of amplifier gainanywhere between zeroand X10. SUPPLY: selects full scaleranges of +1, +2, +4, +10, or £20 volts. (3) VAR GAIN/VOLTS ADJ.: operates in conjunc- tion with AMPLIFIER/SUPPLY control to pro- vide variable control of amplifier gain or selec- tion of + de output voltage, VAR GAIN: operates in conjunction with AM- PLIFIER (selector in VAR, position) to pro- vide variable control of amptifier gain any- where between zero and X10, VOLTS ADJ. : operates in conjunction with SUPPLY control position to provide variable control of de output voltage anywhere between 0 volts and +20 volts, (4) INPUT: banana-type connectors that provide signal inputand circuit common input connec- tions for the instrument. ZERO: a screwdriver adiust that provides com- pensation for de offset, or unbalance, with no signal applied to the 467A INPUT terminals. (6) OUTPUT: banana-type connectors that provide signal outpubtcircuit commonand chassis outpur connections for the instrument. Figure 3-1. Front panel Controls, Indicators and Connectors E Model 467A Section HI 15/230V 0.8A O O CN 467A-B8-0098 [” “ (1) INPUT and OUTPUT connectors; these BNC connectors are connected in parailel with the INPUT and OUTPUT terminals on the front panel. FUSE: contains a {use which provides protec. tion for the primary circuit of the instrument power transformer. This fuse isused for both 115 v and 230 v operation. Power Connector: accepts a 3-wire power cable with safety ground, (4) Line Voltage: atwo-position slide switch; sets the 467A for 115 or 230 volt operation. Figure 3-2. Rear Panel Controls and Connectors wrgadeyy HOOLG porprdurs "I-ÿ mn Model 467A Éd; АА YO ya *5vg94335 mmm $ Hivd TUNOIS < su ии [ОН | TOHENOI mi — —— ss 3 > NIVO 90 «^^ 3 1 28H $210 Г "POY ZONYIVE A; Why a — TT АЛ + (90820 "10 вю ‘вони i tbit | УЗЕЛ На TVIINIHZAHG HIM AONZNCZH MO 19010} {+013 (РОТЕ) T Muria HO POPE LY o Had УВЫ НВА ) еб УЗАМИ “TEE NEE EA ART № м A (201570 *e0) (1015) Cray | bid (61104 121 e мифу a WM | os sil HOH Art A Fl GD IL MAS — M3V8933-5- + бен #2 | 2212 ray ми OV | AS mi umi т “Ле АННАН PRE xovgdaaJ- X Dei OEM Section IV Model 467A Section IV SECTION IV THEORY OF 4-1. INTRODUCTION. 4-2. The Model 467A Amplifier circuits include a high frequency amplifier, a low frequency amplifier, a two-stage differential amplifier, a driver amplifier, and two power amplifier stages. These circuits pro- vide two modes of operation, the power amplifier mode and the power supply mode, 4-3, Whenthe AMPLIFIER/SUPPLY switch is in the AMPLIFIER position, the gain canbe set in fixed steps of X1, X2, X56 and X10, When the switch is in the AMPLIFIER/ VAR position, the VAR GAIN/ VOLTS ADJ control can be used to set the amplifier gain to any value between zero and ten. The input signal is applied to the attenuator, which selects the gain to be used by the instrument amplifier circuitry. Ac and dc feedback stabilize the amplifier gain. Compensation for de offset, or unbalance, is provided by a ZERO adjust control on the front panel. 4-4, Whenthe AMPLIFIER/SUPPLY switch is in the SUPPLY position, the amplifier provides five power supply voltage ranges: +1, +2, +4, +10 and +20 volts, variable from plus through zero to minus for each range, An internal dc reference voltage (plus or minus) is applied tothe amplifier portion, which pro- vides a regulated de voltage at the QUTPUT terminals of the instrument. 4-5. BLOCK DIAGRAM DESCRIPTION. 4-6. Figure 4-1 shows the block diagram for the 467A. The input signal is applied to the high and low frequency amplifiers. The high frequency amplifier (Q101) amplifies the ac signal; the low frequency am- plifier (Q108 through Q110) amplifies the de and low frequency signals. The amplified input signal is then applied through the differential amplifier (Q102 and Q103), amplifier (Q104), and driver amplifier (Q105) to emitter followers (Q106 and Q107). Power ampli- fiers Q1 and Q2 (driven by Q106) and Q3 and Q4 (driven by Q107) provide a balanced signal to the QUTPUT connectors. 4-7. At frequencies above 1 MHz, negative feedback from the driver amplifier Q105 is applied to Q191 through C122 and R129 to provide a decrease ín dis» tortion and remove the power amplifiers from the feedback loop. Negative feedback from Q105 is applied to differential amplifiers Q102 and Q103 through R120, CiibSand R119 to improve frequency response of the instrument. Gain controlfor highirequencyamplifier Q101 is supplied from the output of the power amplifiers (Q1 through Q4) through R148 and R130, 4-8. At frequencies between dc and 50 KHz, negative feedback from the output provides de gain control and balance adjust for the low frequency amplifiers Q108 through Q110. ZERO adjust RS provides compensation for dc unbalance of the signal applied to the low fre- quency amplifiers. Relay K1 protects the external load against current surges during turn-on and turn-off. OPERATION 4-9. SCHEMATIC DIAGRAM DECRIPTION. 4-10. Thefollowing paragraphs give a detailed descrip- tion of the Model 467A Amplifier circuits. Refer io Figures 5-13 and5-14, Section Y , {for the schematic diagrams of the instrument. 4-11. HIGH FREQUENCY AMPLIFIER. 4-12, Trimmer capacitors C301, C303 and C305 can be adjusted to provide the desired frequency response characteristics for the instrument. Ac input signals from the attenuator are applied through C101 to the high {frequency amplifier Q101. The signal is amplified by Q101 and coupled through C104 to the base circuit of Q102. The RC networks, C105, R112, C106 and R114 are used to improve the frequency response characteristics of the amplifier @102. The bias volt- age of Q101 is determined by resistive divider R103 and R104. Ac feedback from power amplifiers (@1, Q2, Q3, and Q4) is applied through R148 to provide ac gain adjust for Q101, 4-13. LOW FREQUENCY AMPLIFIER. 4-14. When the AMPLIFIER/SUPPLY selector is in the SUPPLY position, +7 and -7 volts are supplied from an internal reference, through resistive dividers, to the amplifier input. Each SUPPLY position (+1, +2, +4, +10 and +20) permits setting the de output voltage to any + value withinthe range selected. The low frequency amplifier circuit (Q108, Q109 and Q110) am- plifies the de and low frequency input signal and drives Qi03. The bias voltage for the low frequency amplifier is controlled by R132 and R133 and the ZERO control RS. Transistor Q110 is a current source for the dif- ferential amplifiers Q108 and Q109. Inductors L101 and L102 control the frequency response of the low frequency amplifier (at higher frequencies) by causing degeneration of Q108 and Q108 emitters. High fre- quencies present at Q109 collector are shorted to ground by C1098. Low frequency stabilization and over- all amplifier gain (between de and 50 KHz)are provided by applying de feedback from the OUTPUT to Q109 base. The ZERO potentiometer R5 provides an adjust- ment to compensate for dc drift in the instrument. Varying R35 changes the voltage at Q109 base, thereby changing the output level of the low frequency ampli- fier, 4-15. DIFFERENTIAL AMPLIFIER. 4-18. Differential amplifiers Q102 and Q103 provide an output proportional fo the input signals from the high frequency amplifier Q101 and the low frequency amplifier circuit (Q109 and Q110). The high fre- quency ac signals are coupled to Q102 through C104; the dc and low frequency signals from the low fre- quency amplifier are direct-coupled to differential amplifier Q103. Capacitor C108 bypasses any high frequency ac from the low frequency amplifier to 4-1 Section IVY ground. C109 bypasses any high frequency signals present at the base of Q103. Ac feedback from Q105 collector circuit is applied through C115 to the base circuit of Q102 for high frequency gain stabilization. 4-17. VOLTAGE AMPLIFIER, 4-18, The voltage amplifier Q104 supplies the majority of the voltage gain for the instrument. Degeneration at low frequencies is provided by R127 in the Q104 emitter circuit; C116 provides added phase stability at high frequencies. Current through R125 provides the bias current for Q105, Breakdown diode CR104 establishes the proper voltage at QT 04 coliector and maintains a de sirnal path from Q104 Collector to Q105 hase. 4-19. DRIVER AMPLIFIER. 4-20. Driver amplifier Q105 is driven by current am- plifier Q104 and supplies the signal to the power out- put amplifiers. Transistors Q108 and Q107 are for- ward biased by diodes CR108 through CR112 and under no-signal condition are conducting slightly fo reduce cross-over distortion in the output signal. 4-21. OUTPUT CIRCUITS. 4.22, Transistors Q1 through Qé provide a comple- mentary symmetry output. Ql and Q2, driven by emitter follower Q108, provide a low output impedance. Q3 and Q4, driven by Q107, form a unity gain feed- back amplifiér. This causes Q3dand Qé foactasa PNP emitter follower, which is necessary to provide the complementary symmetry output. 4-23, EXTERNAL LOAD PROTECTION, 4-24. The external! load connected to the 467A is pro» tected during furn-onand turn-off, from current surges and voltage transients, by relay K1. The relay con- tacts openthe circuit tothe OUTPUT connectors when the relay is de-energized. When the instrument is turned ON, Ki remains de-energized for about 300 milliseconds. This delay permits the instrument to stabilize before the output is connected to the load. The 300 millisecond delay is caused by the RC time constant of C110 and R161. When the instrument is turned off, the relay quickly de-energizes and opens the circuit to the OUTPUT connector. 4-2 Model 467A POWER SUPPLY CIRCUIT DESCRIPTION. 4-26, The 467A primary power supply consists of two regulated power supplies {34 and +34 volts), and five reference supplies (+7, -7, +15, -15 and +30 volts). Either 115 or 230 volts ac is connected to the instru- ment through switch ST and fuse FI to Ti primary. Switch 82 {slide switch on rear panel) connects T1 primary windings in series for 239 volt operation, or in parallel for 115 volt operation. The LINE ON lamp DSi glows when primary power is applied tothe instrg- ment. | 4-27. MINUS 34 VOLT SUPPLY, 4-28, Transistor @112 in conjunction with R156, CR129, and CR130 provide a constant current source which provides base drive for @b and Q6, Q112 also provides current to keep CR131, CR132, CR133, and CR135 conducting, R2 and Q5 share the load current to reduce the dissipation in Q6. For small load currents Q5 is turned off and resistor RZ supplies the current, As the load current increases,the base of Q5 is forward biased and Q5 conducts, sharing the current, As the load current is increased further, CR134 is forward biased at a current level determined by R159. This will reduce the current in CR135 to zero causing the supply voltage to go to zero also, 4-29, PLUS 34 VOLT SUPPLY. 4-30. The +34 volt supply provides regulated voltage to the power amplifier circuits. Breakdown diode CR143 establishes the reference at the base of Q8, Potentiometer R163 adjusts the current limit setting for the +34 volt supply. 4-31. REFERENCE SUPPLY. 4-32, The diode regulated reference supply {refer to Figure 5-14)provides +7, -7, +15 and -15 voltages. Capacitors C126 and C128 filter the ac voitages. Breakdown diodes CR146 and CR147 maintain a +15 reference voltage at the junction of R149 and R150. The series arrangement of diodes CR120 and CR121 (forward biased diodes) and CR122 and CR123 (re- verse biased diodes) compensates for temperature and provides a constant -15 reference voltage at the junction of R151 and R152. The plus and minus 7 volt reference voltages are obtained in the same manner as the plus and minus 15 reference voltages, Series regulator Q111 provides regulated +30 volts to the positive side of the reference supply. 4-25. ES La A i “ u
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