HP 8900B User's Manual
Contents
1. ma WIRING ONLY SIDE OF BOARD i COMPONENTS SIDE OF BOARD VIEWED FROM COMPONENTS SIDE OF BOARD 12 3 4 5 6 7 8 9 10 H P i3 14 15 Figure 7 1 Printed Circuit Board Diagram SALES AND SERVICE OFFICES UNITED STATES and CANADA ALABAMA Huntsville 35802 2003 Byrd Spring Rd S W 12051 881 4591 TWX 510 579 2204 ALASKA Bellevue Wash 98004 11656 N E 8th Street 2061 454 3971 TWX 910 443 2303 ARIZONA Scottsdale 85251 3009 No Scottsdale Rd 602 945 7601 TWX 602 949 0111 Tucson 85716 3 232 So Tucson Blvd 1602 623 2564 TWX 602 792 2759 CALIFORNIA North Hollywood 91604 3939 Lankershim Bivd 213 877 1282 and 766 3811 TWX 910 499 2170 Sacramento 95821 2591 Carlsbad Ave 816 482 1463 TWX 916 444 8683 San Diego 32106 1055 Shafter Street 714 223 8103 TWX 714 276 4263 Palo Alto 94303 1101 Embarcadero Rd 415 327 6500 TWX 916 373 1280 COLORADO Englewood 80110 7965 East Prentice 303 771 3455 TWX 910 935 0705 CONNECTICUT Middietown 06457 589 Saybrook Rd 203 346 6611 TWX 710 428 2036 FLORIDA Miami 33125 2907 Northwest 7th St 305 635 6461 Orlando 32803 621 Commonwealth Ave 305 425 5541 TWX 305 841 2568 St Petersburg 33708 410 150th Ave Madeira Beach 1813 391 0211 and 391 1829 TWX 13 391 0666 GEORGIA Atlanta 30305 3110 Maple Drive N E 404 233 1141 TWX 810 751 3283 HAWAII North Hollywood2. TABLE OF CONTENTS Model 89008 Section Page Section Page 1 GENERAL 1 1 4 7 Description of Operation 4 1 1 1 Introduction 1 1 4 12 Monitor Output 4 2 1 5 Instrument Identification 1 1 V MAINTENANCE TIEN 5 1 H INSTALLATION Introduction 5 1 2 1 Introduction Performance 2 3 Unpacking and Inspection Test Equipment Required 5 1 2 5 Installation Troubleshooting and 2 4 2 8 Mechanical Disassembly Procedures 5 4 2 10 Power Requirements Top and Bottom Covers 5 4 2 15 Repackaging for Shipment Right and Left Side Covers 5 4 5 4 1 RF Detector Diode 5 4 3 1 Introduction 1 Adjustment and Calibration 5 5 8 3 Controls and Indicators 3 1 Power 5 8 3 5 Operating Precedures ideal Detector Diode Check 5 5 3 8 Measurement Procedure i del Chopper Performance 5 3 3 19 Using the DC Reference Output 3 2 Power Level Calibration 5 5 3 23 Operational Guide k 3 2 3 25 5 9 72 VL REPLACEABLE PARTS 6 1 3 30 Custom Calibration Chart PE 6 1 Introduction 6 1 3 33 Importance of the Oscilloscope 3
3. 6 2 8900B Bottom 7 1 Printed Circuit Board Assembly 7 2 7 2 Detector Block Disassembly 7 3 7 3 Schematic Diagram 8900B 7 3 LIST OF TABLES Number Title Page 1 1 1 0 3 1 Attenuation Requirements 3 1 5 1 Recommended Equipment List 5 1 5 2 Performance Checks EE 6 1 Reference Designation 6 2 6 2 Replaceable scias Si 6 4 iil Section I Table 1 1 RF CHARACTERISTICS RF range 50 to 2000 MHz RF power range 10 to 200 mw may be increased through use of external attenuators or direction al couplers RF power accuracy 51 5 45 0 6 db with custom calibration curve RF power precision 0 1 db RF pulse width gt 0 25 usec Pulse repetition rate 1 5 MHz maximum RF impedance 50 ohms RF VSWR lt 1 25 Level 0 2 v for 20 mw input Impedance 150 ohms nominal Bandwidth 1 kHz to 7 MHz Table 1 1 DOTEUE Busu e i irs Model 89008 POWER 105 to 125 v or 210 to 250 v 50 to 60 Hz AUXILIARY EQUIPMENT REQUIRED Oscilloscope or equivalent hp 140A WEIGHT net 5 9 kg 10 lbs 4 5 kg shipping 13 lbs DIMENSIONS i i 90 90 5 Die NOTES 8 DIMENSIONS IN INCHES AND MILLIMETERS REAR APRON RECESS DETACHABLE POWER CORD 1 i i i
4. 8 j TERMINATION DEMOD OUT Specifications Model 8900B Section I Paragraphs 1 1 to 1 6 SECTION GENERAL INFORMATION 1 1 INTRODUCTION 1 2 The 8900B Peak Power Calibrator provides a convenient means for measuring the peak RF power of pulses in the range of 50 to 2000 MHz The power level is read out directly on the panel meter and is independent of repetition rate less than 1 5 MHz and pulse width greater than 0 25 usec 1 3 In operation the 8900B provides the circuitry to compare an internal standardized de reference level with the demodulated RF pulses The compar ison ts done visually on an oscilloscope The meter actually reads out the variable de reference level in terms of milliwatts 1 4 Complete specifications for the 8900B are given in Table 1 1 1 5 INSTRUMENT IDENTIFICATION 1 6 Hewlett Packard uses a two section eight digit serial number on instrument rear panel to identify instruments 000 00000 The first three digits are a serial prefix number and the last five digits refer to a specific instrument If the serial prefix on your instrument does not appear on the title page of this manual there are differences between the manual and your instrument which are described in the Appendix or in a Manual Change Sheet included with the manual If the change sheet is missing the information can be supplied by your local sales office Figure 1 1
5. 3 13 Turn ON the source of RF power to the 8900B 3 14 Set the Function Switch to the MEAS position 3 15 With the oscilloscope dc coupled synchronize the sweep if possible from the pulse source with the sweep time set to provide optimum visual obser vation If necessary use the internal synchronization of the oscilloscope 3 16 Using the COARSE and FINE controls adjust the dc reference voltage until the adjustable hori zontal line coincides with the peak of the pulse as displayed on the oscilloscope See Fig 3 3 NOTE For optimum resolution use the highest practical oscilloscope vertical sensi tivity Keep the trace in view with the vertical position control Figure 3 3 Pulse Measurement 3 17 Read the peak power on the front panel meter if external attenuation is used determine actual peak power using Table 3 1 NOTE The reading observed on the meter is accurate within 1 5 db This reading may be applied to the Custom Calibration Chart Fig 3 4 furnished as an accessory with the 8900B for a peak power accuracy of 0 6 db These accuracies are based on absolute worst case errors 3 18 The NULL control need not be adjusted for repetitive measurements 3 19 USING THE DC REFERENCE OUTPUT 3 20 The DC REF OUT connector is provided to permit use of a chopping system operating at other than line frequency if desired For this operation it is necessary to deactiv
6. 5 20 Power Level Calibration 5 21 Table 5 1 provides a list of Recommended Test Equipment for Performance Checks and Calibration over the full frequency range of the 8900B RF Generator substitutions may be made however depending upon the 5900 application and availab Figure 5 5 Chopper Performance 5 5 Section V Paragraphs 5 22 and 5 23 a through i equipment For example 8 6 Frequencies below 500 MHz can be calibrated with power from an hp 230A Power Amplif ier driven by an hp 3200B VHF Oscillator or an hp 608 series Signal Generator Frequencies from 1 to 2 GHz may be calibrat ed using power f rom the 8614A Signal Gener ator in combination with a 489A TWT Ampli fier This combination will allow checks and calibration at the frequencies used on DME ATC Air Navigation equipment NOTE With any type of RF Power Source particular attention must be paid to the reduction of harmonies Appropriate low pass filters are usually necessary The following procedures will use 900 MHz the optimum calibration frequency Path Attenuation Check Connect equipment as shown in Figure 5 6 UG298 U CW RF LOW SOURCE PASS FILTER Model 8900B b Adjust the RF Generator to 900 MHz and without changing the frequency turn the RF output off c Rotate the 8900B Function Switch to the CAL position d Set the oscilloscope vertical amplifier to direct cou
7. 8900B Peak Power Calibrator Section IT Model 39008 Figure 2 1 P INSTRUCTIONS REMOVE TILT STAND FEET AND PLASTIC TRIM 2 ATTACH TRIM STRIP ANO FLANGES KEEPING LARGE NOTCH ON F ANGE TO INSTRUMENT BOTTOM COVER FOOT RELEASE BUTTON PLASTIC TRIM MOUNTING ADMESIVE BACKED FLANGE Figure 2 1 Rack Mounting Instrument Model 59008 Section Paragraphs 2 1 to 2 16 SECTION Il INSTALLATION 2 1 INTRODUCTION 2 2 This section contains information on unpack ing inspection repacking and installation 2 3 UNPACKING AND INSPECTION 2 4 Inspect instrument for shipping damage as Soon as it is unpacked Check for broken knobs and connectors inspect cabinet and panel surfaces for dents and scratches If instrument is damaged in any way or fails to operate properly notify carrier immediately see warranty statement on the inside front cover of this manual For assistance ot any kind including help with instruments under warranty contact vour Hewlett Packard field office 2 5 INSTALLATION 2 6 This instrument may be rack mounted after installation in a combining case hp 1052 or a rack adapter frame hp 5060 0797 See figure 2 1 The area not used by the instrument in either case may be covered by a filler panel hp 5060 0794 When rack mounting this instru ment special provision must be made for access to the MON OUT and DC REF OUT connections which are mou
8. If not adjust R20 NOTE If balance cannot be attained adjust R20 for minimum separation of the hori zontal lines Then adjust the COARSE and FINE panel controls until the horizontal CW RF SOURCE OSCILLOSCOPE 431 POWER METER Figure 5 7 Meter Calibration Setup Model 89008 lines coincide Adjust R18 until the panel meter reads exactly 100 mw 0 db j Verify the NULL adjustment by repeating steps e through b of the procedure k Rotate the 8900B Function Switch to the MEAS position 1 Turn the RF Generator on and reduce the power output as indicated on the CW Power Meter by exactly 10 db m Adjust the COARSE and FINE controls on the 8900B until the two horizontal lines on the oscilloscope exactly coincide The RF Peak Power Meter should read 10 db NOTE If the meter does not read 10 db note the error and readjust the COARSE and FINE controls until the meter reads exactly 0 db Then readjust R18 until the Section V Paragraphs 5 23 j thru r meter indicates the same error and in the same direction above or below 0 db as it did at 10 db n Increase the RF Generator output by exactly 10 db as read on the CW Power Meter o Repeat steps h through m until 0 db and 10 db read correctly p Verify the NULL adjustment by repeating steps b through e of this procedure Ifthe NULL control is adjusted repeat steps f through o q Rotate the 8900B Function Switch t
9. RF Input Connector This type N connector allows an RF source of power to be connected to the 8900 for measurement Maximum power which may be connected directly to this input is 2 watts peak 1 watt average Video Output Connector This connector is used to connect the 8900B chopper output to a suitable oscilloscope for the measurement comparison procedure 10 11 12 Model 89008 Video Null Control The Video Null Control is used to balance out the effect of detector bias Fine Control Coarse Control These controls are used to adjust the internal dc reference level which is read out on the Peak RF Power Meter in terms of milliwatts Bolometer Output Connector This connector is used to connect a CW Power Meter to the 8900B for calibrating the instrument Normally this connector has a 50 ohm termination hp 908A connected to it DC Reference Output These two terminals provide a DC output level directly related to the internal DC reference levei monitored by the Peak RF Power Meter Monitor Output This BNC connector allows the unchopped output of the detector to be observed Function Switch in MON CAL position This output is AC coupled via an emitter follower Thus a CW signal will not provide a de reference voltage Figure 3 1 Operating Controls and Layout Model 8900B Section Paragraphs 3 1 to 3 12 SECTION OPERATION 3 1 INTRODUCTION 3 2 The 900B Peak Power C
10. 3 6 5 Ordering Information 6 1 3 35 Effect of 8900B Chopper on Oscilloscope Waveforms 3 3 VIL MAINTENANCE 4 1 3 37 Monitor Output 393 4 7 1 Introduction s tet tt ng 7 1 7 3 Printed Circuit Board Diagram 7 1 IV PRINCIPLES OF OPERATION 4 1 7 5 Detector Block Disassembly 7 1 4 1 Definition of Peak Power 4 1 1 7 Schematic ss 7 1 4 4 Method of Measurement 4 1 ii Model 3900B List of lustrations List of Tables LIST OF ILLUSTRATIONS Number Title Pag 1 1 8900 Peak Power Calibrator 1 1 2 1 Rack Mounting Instructions 2 0 3 1 Operating Controls and Layout 3 0 3 2 Null Adjustment 6 56 ne 3 1 3 3 Pulse 3 2 8 4 eal Input 8 3 3 5 Typical Custom Calibration Chart 23 3 3 6 Typical Oscilloscope Display 3 3 3 7 Typical Chopper Waveform 2 3 3 3 8 Effect of Contact Bounce zx 3 9 Modulating Signal Frequency Response e Or e 1 S Mom 8900B Block Diagram Path Attenuation Calibration RF Detector Diode Assembly E Detector Diode Check Setup Chopper Performance Number Title Page 5 6 Path Attenuation 5 7 Meter Calibration Setup PET 6 1 8900 Top
11. exceed the critical specifications Table 5 1 Recommended Equipment List Instrument For Critical Specifications Recommended Type Instrument Power Meter Operation RF Range 50 to 2000 MHz hp 31C with Performance Power Range 1 uw to 10 mw 478 Calibration Accuracy 1 Thermistor Mount Oscilloscope Operation Frequency Range 20 me hp 140A with Performance Sensitivity 2v cm 1402A and 1420A Calibration plug ins Pulse Generator Performance Pulse Width 10usec hp 214A Repetition Rate 10 kHz Output 100 volts negative going Electronic Performance de Range to 300 v hp i10C Voltmeter Calibration ac Range to 300 v Troubleshooting Accuracy 2 High Output CW Performance RF Range 50 to 2000 MHz General Radio Type Source or Calibration Output greater than 25 dbm 280 mw Sources 50 250 MHz 1215B 250 960 MHz 1209B 9 2 GHz 1218A Low Pass Filter Performance Depends on frequency of RF source General Radio Type Calibration 874 F500 874 F1000 874 F2000L Attenuators Performance Attenuation 3 db Weinschel Calibration 10 db 2 required Engineering Accuracy 0 25 db Model 50 3N Model 50 10N Double Female Performance Low VSWR UG 29B U Type N Connector Calibration 150 ohm Load Performance Can be assembled using a UG 88 U BNC connector and a 150 ohm 10 1 watt carbon composition resistor Section V Model 89008 Table 5 2 Table 5 2 Performance Checks RF POWE
12. fxd comp 6 8K ohm 5 1 2w 0686 4715 fxd comp 470 ohm 5 1 2w 0724 0059 fxd 60 ohm 1 1 4w Part of Z2 0812 0060 fxd ww 5K ohm 5 5w 0812 0059 fxd ww 6K ohm 5 5w 0689 1025 fxd comp LK ohm 5 lw 2100 0764 var ww 50 ohm 10 2w 0727 0937 fxd car flm 3010 ohm 1 1 2w 2100 0768 var ww 1 5K ohm 5 2w 0686 6815 fxd comp 680 ohm 5 1 2w 0686 1525 fxd comp 1 5K ohm 5 1 2w 2100 0767 var ww 500 ohm 10 2w dual 2100 0763 var ww 30 ohm 10 3w 2100 0766 var ww 400 ohm 5 2w Model 8900B Table 6 1 Reference Designation Index Cont d Reference inti REUS 0727 0974 R fxd car flm 1540 ohm 1 1 2w 2100 0765 R var ww 50 ohm 5 2w 0727 0956 R fxd car flm 40 91 ohm 1 1 2w 21 0686 4715 R fxd comp 470 ohm 5 1 2w 0686 2215 R fxd comp 220 ohm 5 1 2w 0686 3335 fxd comp 33K ohm 5 1 2w fxd comp 18K ohm 5 1 2w R 0686 1835 R 0686 1035 R fxd comp 10K ohm 5 1 2w 0686 4725 R fxd comp 4 7K ohm 5 1 2w R 0686 1025 fxd comp 1K ohm 5 1 2w 0758 0006 fxd met flm 10K ohm 5 1 2w Switch Power P o 3 Switch Snap Slide Switch 3 position OFF MON CAL MEAS Transformer Power Si 52 3101 0033 3100 0762 9100 0271 TL Wi 8120 0078 Power Cord Wa 08900 60003 Cable Assembly i
13. the highest practical vertical sensitivity on all oscilloscope displays 3 10 Check to see that the 50 ohm termination 908A is properly connected at the BOL OUT connector on the rear panel 3 11 Connect the source of RF pulse power to be measured to the RF IN connector on the front panel through a suitable attenuator or coupler if required NOTES 1 Attenuators or couplers shouid be selected to provide attenuation as shown in Tabie 3 1 Attenuation F z6 Table 3 1 Attenuation Requirements 2 The attenuator calibration accuracy is directly additive to the basic power measuring accuracy of the 8900B Precision pads of known accuracy should be used 3 Set the Function Switch to the MON CAL position The pilot light should light indicating power to the instrument and the front panel meter pointer should indicate within the CAL marking on the meter scale This operation confirms that the de reference supply and meter movement are working satisfactorily 3 12 With the source of RF pulse power to the 8900B turned OFF and the oscilloscope set to free run adjust the VIDEO NULL control until the two horizon tal lines observed on the oscilloscope are superim posed See Fig 3 2 This operation balances out the detector diode bias from the video waveform which might otherwise be read as RF power Figure 3 2 Null Adjustment Section III Paragraphs 3 13 to 3 28
14. 219 Campviile Rd 607 754 0050 TWX 510 252 0890 NORTH CAROLINA High Point 27262 1923 N Main Street 819 882 6873 TWX 510 926 1516 OHIO Cleveland 44129 5579 Pear Road 216 884 9209 TWX 216 888 0715 Dayton 45409 1250 W Dorothy Lane 513 298 0251 TWX 513 944 0090 OKLAHOMA Oklahoma City 405 235 7062 PENNSYLVANIA Camp Hill 717 737 6791 West Conshohocken 19428 144 Elizabeth Street 215 248 1600 and 828 6200 TWX 518 660 8715 Monroeville 15146 Monroe Complex Building 2 Suite 2 Moss Side Blvd 14121 271 5227 TWX 710 797 3650 TEXAS Dallas 75209 P O Box 7166 3605 inwood Rd 214 357 1881 TWX 910 861 4081 Houston 77027 0 Box 22813 4242 Richmond Ave 713 667 2407 TWX 713 571 1353 UTAH Salt Lake City 84115 1482 Major St 801 486 8166 TWX 801 521 2604 VIRGINIA Richmond 23230 2112 Spencer Road 703 282 5451 TWX 710 956 0157 WASHINGTON Bellevue 98004 11656 N E 8th St 206 454 3971 TWX 910 443 2303 GOVERNMENT CONTRACTING OFFICE San Antonio Texas 78226 Hewlett Packard Contract Marketing Division 225 Billy Mitchell Road 512 434 4171 TWX 512 571 0955 CANADA Montreal Quebec Hewiett Packard Canada Ltd 8270 Mayrand Street 514 735 2273 TWX 610 421 3484 Telex 01 2819 Ottawa Ontario Hewlett Packard Canada Ltd 1762 Carling Avenue 613 722 4223 TWX 610 562 1952 Toronto Ontatio Hewlett Packard Canada Ltd 1415 Lawr
15. Calif 91604 3939 Lankershim Blvd 213 877 1282 TWX 910 499 2170 ILLINOIS Skokie 60076 5500 Howard Street 312 677 0400 THX 910 223 3613 INDIANA Indianapotis 46205 3919 Meadows Dr 317 546 4891 TWX 317 635 4300 LOUISIANA New Ofleans 504 522 4359 MARYLAND Baltimore 21207 6660 Security Blvd 301 944 5409 TWX 710 862 0850 Rockville 20852 12303 Twinbrook Pkwy 301 427 7560 TWX 710 828 9684 MASSACHUSETTS Burlington 01803 Middlesex Turnpike 617 272 9000 TWX 710 332 0382 MICHIGAN Southfield 48076 24315 Northwestern Hwy 313 353 9100 TWX 313 357 4425 MINNESOTA St Paul 55114 2459 University Ave 612 646 7881 TWX 910 563 3734 MISSOURI Kansas City 64114 9208 Wyoming Place 816 333 2445 TWX 910 771 2087 St Louis 63144 2812 South Brentwood Blvd 314 644 0220 TWX 910 760 1670 NEW JERSEY Eatontown 07724 12012 747 1060 Englewood 07631 391 Grand Avenue 201 567 3933 TWX 510 230 9709 NEW MEXICO Albuquerque 87108 501 Lomas 8140 N E 505 26 TWX Las Cruces 88001 114 5 Water Street 5051 526 2486 TWX 910 982 0550 NEW YORK New Yotk 10021 236 East 75th Street 212 879 2023 TWX 210 581 4376 Rochester 14623 39 Saginaw Drive 716 473 9500 TWX 510 253 5981 Poughkeepsie 12601 82 Washington Street 914 454 7330 TWX 914 452 7425 Syracuse 13211 5858 East Molloy Rd 315 454 2486 TWX 710 541 0482 Endicott 13764 1
16. HP 89008 OPERATING AND SERVICE MANUAL HEWLETT PACKARD CERTIFICATION The Hewlett Packard Company certifies that this instrument was thoroughly tested and inspected and found to meet its published specifications when it was shipped from the factory The Hewlett Packard Company further certifies that its calibration measurements are traceable to the U S National Bureau of Standards to the extent allowed by the Bureau s calibration facility WARRANTY AND ASSISTANCE All Hewlett Packard products are warranted against defects in materials and workmanship This warranty applies for one year from the date of delivery or in the case of certain major components listed in the operating manual for the specified period We will repair or replace products which prove to be defective during the warranty period No other warranty is expressed or implied We are not liable for consequential damages For any assistance contact your nearest Hewlett Packard Sales and Service Office Addresses are provided at the back of this manual OPERATING AND SERVICE MANUAL MODEL 8900B PEAK POWER CALIBRATOR SERIALS PREFIXED Ges This manual covers all 8900B Peak Power Calibrators with three digit serial numbers and eight digit ser ial numbers with 623 prefixes Hee Copyright HEWLETT PACKARD COMPANY GREEN POND ROAD ROCKAWAY NEW JERSEY 18900 90208 1966 U S A Printed MAY 1966 Table of Contents
17. IMPORTANCE OF THE OSCILLOSCOPE 3 34 A basic factor in the philosophy of the 3900B is that of actual observation of the puise waveform during the measurement While this requires the use of a suitable auxiliary oscilloscope it is considered important in the reduction of subtle error ome of which are variations in pulse width rate or shape It has an inherent advantage in permitting measure ment of intermediate levels of power in a complex waveshape The operator may ignore characteristics such as overshoot if they contribute nothing to the effectiveness of his system as he chooses or he may measure them In some applications the user may be monitoring the effectiveness of a system at the time the measurement is made in an effort to correlate system performance to peak RF power It then becomes important that he verify that the output power has not changed by even a few tenths of a db at the time of the reading A typical oscilloscope dis play from the 8900B during a measurement is shown in Figure 3 6 Figure 3 6 Typical Oscilloscope Display 3 35 EFFECT OF 8900B CHOPPER ON OSCILLO SCOPE WAVEFORMS 3 36 The 60 cycle mechanical chopper effects the demodulated oscilloscope waveforms of some double pulsed RF signals and pulsed RF signals having a long duty cycle This effect is caused by normal contact bounce The decay time for the bounce some times approaches 600 usecs Figure 3 7 sho
18. If you have any questions contact your local hp Sales and Service Office see lists at rear of this manual a Place instrument in original container if available If original container is not available it can be purchased from your nearest hp Sales and Service Office If original container is not used b Wrap instrument in heavy paper or plastic before placing in an inner container Use plenty of packing material around all sides of instrument and protect panel faces with cardboard strips d Place instrument and inner container in a heavy carton or wooden box and seal with strong tape or metal bands e Mark shipping container with Delicate Instrument Fragile etc NOTE If the instrument is to be shipped to Hewlett Packard for service or repair attach to the instrument a tag identifying the owner and indicate the service or repair to be accomplished inelude the model number and serial number of the instrument In any correspondence identify the model and serial numbers Section Figure 3 w Function Switch This switch determines the operating condi tions of the 8900B for monitoring calibrating the instrument or measuring Fuse AC line 0 3 amp for 115v input 0 15 amp for 230v input Pilot Light Peak RF Power Meter This meter monitors the internal variable de reference voitage level The meter is calibrated in terms of milliwatts and decibels with respect to 100 mw
19. R ACCURACY General Power calibration is checked by first measuring the 8900B path attenuation This is done at a power level within the normal measuring range of the instrument 10 to 23 dbm With an RF Power Meter hp 431C 178A replacing the rear mounted 50 ohm termination AT2 the CW incident power in dbm is determined by RF Power Meter reading path attenuation Calibration and checking at 900 MHz is recommended but a detailed performance evaluation would require checks at convenient frequency intervals between 50 MHz and 2 GHz Measure and record path attenuation 1 Connect equipment as shown in Figure 5 1 2 Set 8900B Function Switch MEAS RF Source Rp Output frequency 900 MHz FILTER H POWERMETER RF Power Meter Range 15 dbm Figure 5 1 Path Attenuation Check Adjust RF power level until RF Power Meter reads 16 dbm Disconnect 8900 RF IN and BOL OUT and replace it with a UG 29B U Adapter The Power Meter increase by approximately 16 db Calculate exact change and record Check Calibration Connect equipment as shown in Figure 5 2 Set 89008 OSCILLOSCOPE Function Switch MEAS Power Meter ME eum Range Switch 5 dbm POWER METER Oscilloscope Vert Sens Horiz Sweep Figure 5 2 Calibration Check RF Source RF Output Zero or Off Perform Null adjustment on 8900B see paragraph 3 13 Adjust RF Source output level so Power Meter reading added to path attenuation recorded in st
20. a Centrum Tel 08 83 08 30 Instrument 4628 Incunagatan 28A Moindat 4 Tel 27 58 00 SWITZERLAND Max Paul Frey Wankdortfeidstiasse 66 Berne Tel 1031142 00 78 TAIWAN Hwa Sheng Electronic Co Ltd P O Box 1558 21 Nanking West Road Taipei Tel 36076 45936 TURKEY Teiekom Engineering Bureau P 0 Box 376 Galata istanbul Tel 49 40 40 UNITED KINGDOM Hewlett Packard Ltd Dallas Road Bedford England Tel 68052 VENEZUELA Citec C A Edif Arisen Of No 4 Avda Francisco de Miranda Chacaito Caracas Tel 71 88 05 YUGOSLAVIA Belram S A 83 Avenue des Mimosas Brussels 15 Belgium Tel 35 29 58 n For Sales and Service Assistance in reas Not Listed Contact EUROPE Hewlett Packard S A 54 Route des Acacias Geneva Switzerland Tel 022 42 81 50 ELSEWHERE Hewiett Packard 1501 Page Mill Road Palo Alto California 94304 U S A Tel 415 326 7000 HE PACKARD 5 66
21. alibrator provides a simple means of measuring the peak power of pulsed RF in the 50 to 2000 MHz frequency range The internal circuitry provides a calibrated de level which is read on the front panel meter in terms of milliwatts and db An internal detector demodulates the pulsed RF input signal to be measured An oscilloscope is used to compare the adjustable dc level and the de modulated pulses The horizontal line representing the de level is adjusted to coincide with the pulse peak to be measured The 8900B front panel meter will indicate the peak power 3 3 CONTROLS AND INDICATORS 3 4 Front and rear panel controls indicators and connectors are shown in Fig 3 1 Each control indicator and connector is identified by a number to key each to the identifying text below the photographs 3 5 OPERATING PRECEDURES 3 6 With power connected to the 8900B see para graph 2 10 for power requirements rotate the func tion to the MON CAL position 3 7 This instrument requires no warm up time CAUTION DO NOT exceed power input limit at front panel RF IN connector as specified on the meter 2 WATTS PEAK OR 1 WATT AVERAGE or damage WILL result See para graph 3 12 and Table 3 1 3 8 MEASUREMENT PROCEDURE 3 9 Connect an oscilloscope to the VIDEO OUT connector NOTE The oscilloscope bandwidth required is dependent on the waveshape being measured The vertical amplifier must be de coupled For optimum resolution use
22. andards laboratory equipment The high quality forward biased diode is an order of magnitude more stable environmen tally than an uncompensated bolometer or calori meter 3 27 While the specified accuracy of the Peak Power Calibrator is 50 6 db when using the Custom Calibra tion Chart utilization to a higher degree of accuracy by virtue of its inherent stability is both practical and recommended The 0 6 db figure is based on absolute worst case error It is also based on a minimum of standards equipment to perform a cali bration With high quality standards laboratory type equipment for calibration operation to about 40 3 db worst case error is considered practical 3 28 The worst case errors are contributed by the following Measurement of the 16 db normal path attenuation from the RF IN connector to the CW standard output BOL OUT connector b Power Meter Input VSWR reflection error The typical input VSWR over the 8900B frequency range is shown in Fig 3 5 d Meter tracking and repeatability errors e Operator readout f Possible aging of the detector diode CORRECTION db Model 2y0UB VSWR INPUT FREQUENCY MHZ Figure 3 1 Typical Input VSWR 3 29 Reviewing the factors that can cause errors in the me rement it can be seen that some items are more difficult to correct than others However by use of accurate standards laboratory qual
23. ate the internal chopper and make a connection between the detector diode output and the VIDEO OUT connector This is accomplished by removing the chopper G1 and installing an octal plug with a jumper from PIN 7 PIN 8 The exter nal chopper can be connected with one arm to the DC REF OUT connector and the selecting arm to an oscilloscope If a dual trace oscilloscope is used the external chopper may be eliminated by connecting the 8900B outputs VIDEO OUT DC REF OUT to the 3 2 Model 8900B two vertical inputs of the oscilloscope with the ver tical amplifiers set to the same sensitivity 3 21 Another application of the DC REF OUT con nector is the measurement of one shot or non repetitive waveforms Plotting a curve of Peak RF Power Meter readings vs DC REF OUT voltage produces a calibration of DC output in terms of Peak RF Power 3 22 With this information Peak RF Power of non repetitive or even repetitive wavetorms can be de termined from visual records made with an oscillo Scope camera 3 23 OPERATIONAL GUIDE 3 24 Inthe practical application of the 8900B the following information should assist in providing more accurate results as the capabilities and limitations of the instrument are expanded upon 3 25 ACCURACY 3 26 A basic objective of the 8900B is to provide a peak power measuring instrument of sufficient ac curacy to serve as a working standard without the usual rigorous limitations of st
24. both sides of the board with all of the electrical components This diagram will provide the following facilities Printed Circuit Board circuit tracing b Component replacement of polarized devices such as semiconductors electro lytic capacitors etc 7 5 DETECTOR BLOCK DISASSEMBLY 7 6 An exploded view of the detector block assembly 22 is shown in Figure 7 2 The associated notes show specific details required for diode CR5 replace ment 7 7 SCHEMATIC 7 8 complete schematic for the 8900B is shown in Figure 7 3 7 9 Schematic Notes a Resistance in ohms and capacitance in microfarads unless otherwise specified b front panel designation rear panel designation Q front panel control e screwdriver adjustment f CW clockwise end of variable resistor E de reference path h demodulated RF path i For fuse information see paragraph 2 11 j Numbers shown in parentheses indicate wire color using RETMA Resistor Color Code e g Black Red is 0 2 k o test point circuit board connection point 1 Yr test point m L4 printed circuit board assembly 7 10 Voltage and Resistance Readings 7 11 Voltage and Resistance Readings shown in this section were measured with an 410 electronic voltmeter These readings are typical except as noted in adjustment or calibration procedures of Section V 7 1 Section Model 89008 2
25. c Inc TRW Capacitor Div Tower Mfg Co Dale Electronics Inc Weinschel Engineering Co Inc Methode Electronics Inc Dage Electric Co Inc Microwave Associates Inc Section VI Model 89008 Table 6 1 Table 6 1 Reference Designation Index Reference Stock por 0950 0114 Attenuator fxd 1045 Type Connectors 0950 0082 Termination 50 ohms N male connector hp Model 908A 0180 1796 C fxd elect 40uf 150v C Special Part of Z2 0160 0741 C fxd my 047uf 10 100v 0180 0258 C fxd elect lOuf 25v 1901 0028 Diode Si 400v 0 5 1N1763 can be used for replacement 1900 0013 Detector Diode Part of Z2 See paragraph 5 19 1902 0157 Diode Zener 8 9 9 7v 10 ma 1N2620 1902 0158 Diode Zener 12 0 10 400 mw 1N759 1450 0048 Lamp Indicator Red NE2H 2110 0044 Fuse 3A 250 SLO BLO for 115v operation 2110 0058 Fuse 15 250 SLO BLO for 230v operation 0490 0122 Chopper 6 3v 50 60 Hz Part of W2 Part of 21 Part of AT1 1250 0192 Connector BNC UG 262 U 1510 0007 Binding Post Red 1250 0192 Connector BNC UG 262 U 1510 9006 Binding Post Black 1251 0135 Receptacle Printed circuit board 1120 0167 Meter PEAK RF POWER Part of W2 Part of Z2 Part of ATI Part of AT2 1251 0148 Connector AC Power Cord Receptacle 1854 0006 Transistor NPN 2N706 0692 8215 R fxd comp 820 ohm 5 2w 0692 4735 fxd comp 47K ohm 5 2w 0686 6825
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27. ence Avenue West 416 249 9196 TWX 610 492 2382 Vancouver B C Hewlett Packard Canada Ltd 2184 W Broadway 604 738 7520 TWX 610 922 5059 5 66 HEWLETT PACKARD SALES AND SERVICE OFFICES INTERNATIONAL Electronic Equipment ARGENTINA Mauricio A Suarez Telecommunicaciones Carlos Calvo 224 Buenos Aires Tel 30 6312 34 9087 AUSTRALIA Sample Electronics Vic Pty Ltd 9 11 Cremorne Street Richmond 1 Victoria Tel 42 4757 Sample Electronics N S W Pty Ltd 4 Grose Street Glebe New South Wales Tel 59 6338 AUSTRIA Unilabor H m b H Wissenschaftliche Instrumente Rummelhardtgasse 6 3 P O Box 33 Vienna 1 71 Tel 426 181 BELGIUM Hewlett Packard Benelux S A 20 24 tue de Brussels Tel 11 22 20 BRAZIL Ciental Importacao e Comercio Ltda Rua des Eliseu Guilherme 62 Sao Paulo 8 Tel 70 2318 CHILE Hector Calcagni Casilla 13947 Santiago Tel 6 42 26 DENMARK Tage Olsen A S Ronnegade 1 Copenhagen 0 Tel 29 48 00 FINLAND INTO 0 Meritullinkatu 11 P O Box 153 Helsinki Tel 6 11 33 FRANCE Hewlett Packard France 150 Boulevard Massena Paris 13 Tel 707 97 19 Hewlett Packard France 2 tue Tete d Or Lyon 6 Rhene Tel 52 35 66 GERMANY Hewlett Packard Vertriebs GmbH Kurhessenstrasse 95 Frankfurt a Main Tel 52 00 36 Hewlett Packard Vertriebs GmbH Reginfriedstrasse 13 Munich 9 Tel 49 51 21 Hewlett Packard Vertriebs GmbH B
28. ep A4 above is equal to 20 dbm Power incident upon 8900B is then 20 db or 100 mw Adjust 8900B COARSE and FINE controls for coincidence of oscilloscope traces 8900B meter reading should be 100 mw 1 5 db Reduce RF power level by 5 db and then 5 db more each time adjusting the 8900B COARSE and FINE controls for oscilloscope trace coincidence 8900B readings should be 5 51 5 db and 10 x 1 5 db respectively NOTE ifa calibration check is to be made at more than one frequency steps Al through must be repeated for each frequency Tf a custom calibration chart is supplied the corrected readings must be accurate within 0 6 db at all frequencies between 50 MHz and 2 GHz A custom calibration is invalid after replacement of W1 Zi AT1 Z2 or CR5 Model 8900B Section V Table 5 2 Table 5 2 Performance Checks Cont MONITOR OUTPUT Connect equipment as shown in Figure 2 Set 8900B Function Switch MEAS COARSE and FINE controls Adjust for 20 mw reading on Peak RF Meter Pulse Generator Pulse Amplitude 100 volts negative going Repetition Rate 10 kHz Pulse Width 10 usec Trigger Internal RF Source Output Frequency 900 MHz Oscilloscope Vertical Sensitivity 50 mv cm Adjust level of RF source to 20 mw as determined by 8900B measurement Change 8900B Function Switch to MON CAL position Change oscilloscope connection from 8900B VIDEO OUT to MON OUT connector and measure voltage level The detected pulse le
29. f the diode a Connect the 8900B to a power source set to 115 vac CW RF SOURCE LOW PASS FILTER Figure 5 4 Detector Diode Check Setup POWER METER Section V Paragraphs 5 14 to 5 21 b Connect a de electronic voltmeter to test point Figure 6 1 and 7 3 1 Voltage at test point FEY should be 0 27 9 08 vie NOTE Voltage out of this range usually indi cates a defective diode Connect equipment as shown in Figure 5 4 d Remove chopper Gl from its socket e With the 8900B Function Switch in the OFF position tune the RF Generator to 1 GHz and adjust the output level so the Power Meter in dicates t 100 mw will then be applied to the RF IN connector f Measure the voltage at TP5 which should be nominally 1 vdc A diode not measuring be tween 0 8 and 1 2 vde should be replaced see Paragraph 5 13 5 19 Chopper Performance a Connect the oscilloscope to the VIDEO OUT connector on the Peak Power Calibrator Synchronize the oscilloscope pattern at the chop per frequency 50 or 60 cps and adjust the COARSE control until a square wave the chopper waveform appears on the oscilloscope b Fig 5 5 shows a typical oscilloscope pattern of the chopper operation Duty cycle is approximately 50 Contact bounce will generally increase with use The chopper as sembly G 1 can be readily replaced if contact bounce becomes excessive and impairs obser vations on the oscilloscope
30. ghtening the socket head setscrew Modei 59008 5 14 ADJUSTMENT AND CALIBRATION 5 15 Adjustment procedures for the 8900 are given in Paragraphs 5 00 through 5 00 Recommended test equipment for the adjustment pro cedure is listed in Table 5 1 Do NOT perform the adjustments as a performance check Test limits used in the adjustments should not be construed as part of the specifications 5 16 Power Supply a Connect an electronic voltmeter from positive side of Cl to negative side of C2 Voltage should be nominally 240 CAUTION The Electronic Voltmeter chassis must be ungrounded for the measurements in steps and b b Measure voltage across CR6 from TP1 to TP2 Voltage should be nominally 9 2 vde c Measure voltage and ripple from to ground Voltage should be nominally 11 5 vde with less than 20 mv p p ripple at 125 vac line If not suspect CR7 d Measure ripple between and ground Ripple should not exceed 20 mv p p at 125 vac line If it does suspect CR6 e Connect the Electronic to the DC REF OUT terminals on the rear panel With the FINE and NULL controls turned fully counter clock wise rotate the COARSE control through its full range The dc meter should indicate from slightly negative to at least 1 4 v 5 17 Detector Diode Check 5 18 Diode damage may occur if input power levels exceed 1 watt average or 2 watts peak The following procedure will check the condition o
31. he first cycle of the RF carrier It may charge up in stair case fashion over a period of several cycles but must reach the peak before a measure ment is made The 8900B specification states that 0 25 psec should be allowed for this although Section Paragraphs 4 16 to 4 14 0 10 usec is typical with a 6 foot length of RG 62 U 90 ohm cable and an oscilloscope with 50 pf input capacitance connected to the video output Since no isolating amplifier is employed extremely high external capacitance could increase the time required for the video output to rise to the true peak of the voltage waveform The impedance of the out put circuit is approximately 350 ohms The peak de tector also has a responsibility to remain faithful at low RF carrier frequencies It must not start to discharge while it is waiting for the crest of the next cycle of the RF voltage waveform to appear If it falls by even a few per cent the de output level with in the duration of the pulse would be lower than the true RF voltage peak and an error would be introduced The 8900B was designed to meet its accuracy specification at carrier frequencies down to 50 MHz The upper frequency limit is 2000 MHz A front panel NULL control is included to permit the user to erase the static de bias on the diode from the video presentation While this control need not be reset for a repetitive series of measurements it gives the operator a range of adjustment t
32. ity instru ments and observing the following suggestions very accurate measurements can be made a Calibrate the 16 db nominal attenuation path to an accuracy of 50 1 db or better See par 5 22 b Use a 1 or better CW power meter hp 431C e Calibrate the instrument at the power level to be measured to eliminate meter tracking errors d Tune the input circuit to a VSWR of 1 00 to 1 The above steps should permit operation to a 30 3 db worst case error in the basic range of the instrument 3 30 CUSTOM CALIBRATION CHART 3 31 The Custom Calibration Chart Fig 3 5 supplies correction for errors attributable to the frequency sensitive components in the RF circuitry of the instrument This chart information is obtained by maintaining a constant 100 mw 0 db input to the Peak Power Calibrator and plotting the required meter correction over the frequency range as mea Surements are made 3 32 The worst case errors due to frequency sensi tivity add up to 0 7 db and are contributed by the following elements a The power divider PEAK POWER CALIBRATOR Type 89008 CALIBRATION CHART Seria No Date ABSOLUTE ACCURACY WITH CHART 10645 2 Figure 3 5 Typical Custom Calibration Chart Section Paragraphs 3 29 to 3 36 b The 10 db attenuator The diode detector Associated connectors 3 33
33. l CW source it is generally agreed that 4 6 The average power and peak power of a source are equal if the duty cycle is 1 The voltage wave forms then must be identical for the duration of time the source is turned on assuming a system of constant characteristic impedance or Ro The peak voltage of the CW mode will be the same as the peak voltage when the source is pulsed even though this is not the parameter to be measured It is however a means of correlation between the two Employing a device known as the peak detector we have an ele ment which will respond identically for a duration of time to both a CW and a pulsed source of the same power rating While elements such as a bolometer may respond quite differently to the two depending on the heating effect the peak detector does not This is the princi of the 8900B Peak Power Calibrator 4 7 DESCRIPTION OF OPERATION 4 8 Figure 4 1 is a block diagram illustrating the basic operation of the 8900B It can be seen that a signal applied to the front panel input connector is sent through two paths by virtue of the power divider In one path the signal passes through a 10 db attenu ar POWER OIVIOER INPUT ERMINATION MONITOR a QuTPuT CHOPPER 2 SCOpa DC POWER SUPPLY oc REFERENCE OUTPUT METER i Figure 4 1 8900B Block Diagram ator and is absorbed in a 50 ohm termination In the othe
34. mation on each part a Description of the part see list of abbrevi ations below b Typical manufacturer of the part in a five digit code see list of manufacturers in par 6 8 c Manufacturer s part number d Total quantity used in the instrument TQ column 6 3 Miscellaneous mechanical parts are listed in Table 6 2 6 4 For parts location and identification see Fig 6 1 6 2 and 7 1 6 5 ORDERING INFORMATION 6 6 To obtain replacement parts address order or inquiry to your local Hewlett Packard sales and service office see lists at rear of this manual Identify parts by Hewlett Packard stock number 6 7 Section VI Paragraphs 6 1 to 6 7 To obtain a part not listed include Instrument model number Instrument serial number Description of part Function and location of parts LIST OF MANUFACTURERS 07115 07387 12697 12749 35434 42190 56289 63743 70903 71279 71450 71785 72765 75915 78553 80031 84411 87930 91637 93459 95354 95712 96341 Manufacturer Allen Bradley Co Texas Instrument Inc Motorola Semiconductor Products Inc Corning Glass Works Electronic Comp Dept The Birtcher Corp Clarostat Mfg Co Inc dames Electronics Inc Lectrohm Inc The Muter Sprague Electric Co Ward Leonard Electric Co Belden Mfg Co Cambridge Thermionic Corp CTS Corporation Cinch Mfg Co Drake Mfg Co Littelfuse Inc Tinnerman Products In
35. ncludes J1 6 2 21 08900 60007 Power Divider Assembly Z2 08900 60006 Detector Assembly Z2MP1 2295 0011 Screw mach 4 40 x 3 8 lg 22 2 2190 0071 Washer Lk 4 External Z2MP3 3050 0258 Washer Flat 1 4 od x 119 id 025 thk Z2MP4 5020 2204 Washer Shoulder Z2MP5 08900 00003 Washer Spring Bowed Z2MP6 0360 0364 Terminal Strip 2 Ins 1 Gnd 22 Z2MP8 Z2MP9 Z3 08900 60010 3030 0089 08900 20001 08900 60204 Plate amp Eyelet Assembly Screw Set 1 72 x 1 8 lg Insulator Detector P o C3 Printed Circuit Board Assembly Section VI Table 6 1 Figure 6 1 and 6 2 Ji CAL ADJ ME 74 44 P4 0340 0086 METER SENS 21 in DB ADJ ATI J8 Mi 1400 0162 1 FOR DETAILS 1400 0084 2 817 R26 Z3 SEE FIG 7 i 43 TI FOR DETAILS Fig 6 1 8900B Top View SIA 1200 0020 0340 0097 5060 0703 1400 0099 5040 0700 1490 0032 0340 0090 49 46 Ji RIO RI2 R2 JH R20 Fig 6 2 8900B Bottom View Model 8900B Section VII Paragraph 7 1 to 7 11 SECTION VII MAINTENANCE DATA 7 1 INTRODUCTION 7 2 This section provides the electrical circuit details in the form of schematics diagrams typical voltage and resistance readings etc for mainten ance of the 8900B 7 3 PRINTED CIRCUIT BOARD DIAGRAM 7 4 The Printed Circuit Board 28 diagram in Figure 7 1 shows all of the circuitry on
36. nted on the rear panel of the instrument 2 7 Connect the power cord to the power socket on the rear panel of the 8900B 2 8 VENTILATION 2 9 The 8900B utilizes solid state circuitry Heat is dissipated through conduction and radiation This instrument has been tested to operate satisfactorily in ambient temperatures up to 559 C 131 Venti lation should be provided to avoid exceeding this temperature 2 10 POWER REQUIREMENTS 2 11 The model 8900B can be operated from a 115 or 230 v 410 50 to 60 Hz source An input voltage switch 115v 230v at the rear of the instrument selects the AC operation mode A 3 10 amp fuse in the AC line is used for 115 v operation a 15 100 amp fuse for 230 v operation 2 12 THREE CONDUCTOR POWER CABLE 2 13 To protect operating personnel the National Electrical Manufacturers Association NEMA recommends that the instrument pane and cabinet be grounded Al Hewlett Packard instruments are equipped with a three conductor power cable which when plugged into an appropriate receptacle grounds the instruments The offset pin on the power cable three prong connector is the ground wire 2 14 To preserve the protection feature when operating the instrument from a two contact outlet use a three prong to two prong adapter and connect the green pigtail on the adapter to ground 2 15 REPACKAGING FOR SHIPMENT 2 16 The following is a general guide for repacking for shipment
37. o compen Sate for any possible long term aging effects on the diode This adjustment is made with the Function Switch in the MON CAL position 4 10 In this position also a voltage divider from the reference power supply applies a preset voltage to the de meter to deflect the needle to a calibration mark It should be noted however that unlike some measuring systems the reference supply is not really a critical parameter in the measurement because it is being used only for comparison rather than as an absolute reference for the measurement The meter calibration is the absolute reference 4 11 Now consider the signal path which attenuates the incident power and dissipates the remainder in 50 ohm load This is provided as a convenient means of calibration or standardizing the instrument If the 50 ohm load is replaced by an accurate CW power measuring device such as a bolometer or calorimeter and a CW source is connected to the input connector the effect of the applied power level can be monitored on the average reading CW power meter and the peak reading diode detector simulta neously Therefore one need only to know accurately the attenuation between the front panel input connector and the power meter to determine what effect a known power level at the input has upon the peak RF detector The 10 db pad is introduced to reduce the CW level to one within the range of several commercially avail able power meters The CW so
38. o the MON CAL position Adjust the ac line voltage to 115 vac Adjust R12 until the pointer falls within the calibration marking on the meter r Tighten the locking nuts on the internal adjustable controls R12 R18 and R20 Section VI REFERENCE DESIGNATORS attenuator capacitor diode lamp indicator fuse 7 chopper mechanical jack meter mechanical part plug transistor resistor fixed or variable sauosovuv Sz osHgobh switch transformer test point 7 cable assembly ABBREVIATIONS A ampere AC alternating current capacitor car flm carbon film comp composition db decibel dia diameter elect electrolytic fxd fixed gnd ground Hz hertz id inside diameter ins insulated ik lock ig long ma milliampere mach machine met fim metal film mw milliwatt my mylar od outside diameter p o part of si silicon lhk thick v volt var E variable w E watt ww wire wound ut microfarad Model 89008 Model 8900B SECTION VI REPLACEABLE PARTS 6 1 INTRODUCTION 6 2 This section contains information for ordering replacement parts Table 6 1 lists parts alpha numerical order of their reference designations and indicates the description and hp stock number of each parts together with any applicable notes Table 6 2 lists parts in alpha numerical order by their hp stock number and provides the following infor
39. pling with the direct coupling with the sweep set to free run e Adjust the 8900B NULL control until the two horizontal lines on the oscilloscope coincide Use the highest oscilloscope vertical sensitivity practical for the most precise adjustment f Rotate the 8900B Function Switch to the MEAS position g Turn on RF Generator and adjust the output level until the CW Power Meter reads 100 mw minus the path attenuation determined for 900 MHz The input at the 8900B RF IN connector is 100 mw Figure 5 6 Path Attenuation Check Setup Set 8900B Function Switch MEAS RF Source Output frequency 900 MHz RF Power Meter Range 15 dbm Adjust RF power level until RF Power Meter reads 16 dbm Disconnect 8900B RF IN and BOL OUT and replace it with a UG 29B U adapter The power meter reading will increase by approx imately 16 db Calculate exact change and record Meter Calibration Connect the equipment as shown in Figure 5 7 EXAMPLE If the path attenuation for the particular instrument checked measured 16 2 db at 900 MHz for 100 mw at the 8900 RF IN connector the CW Power Meter should indicate 20 dbm 16 2 db or 3 8 dbm as indicated on the CW Power Meter This will make the power at the 8900B RF IN connector exactly 100 mw h Adjust the COARSE and FINE controls on the 8900 for 100 mw 0 db reading on the RF Peak Power Meter i At this point the two horizontal lines should exactly coincide
40. r path the signal arrives at a diode peak detector which develops a dc level equal to the peak voltage of the RF waveform applied to it The diode is forward biased to bring it to an operating point of maximum stability and to bring it away from the square law region to produce a somewhat more linear change in output voltage for a change in the applied RF level As the block diagram indicated a variable de supply is also included The output of the supply is connected to a de meter which monitors its voltage and to one leg of a mechanical chopper If the chopper is set in operation and its selecting arm is connected to an oscilloscope one can look first at the dc level pro duced by the peak detector in response to an RF voltage and then at the dc level produced from the variable de reference supply In performing a mea surement the variable supply is adjusted until the two voltages are exactly equal The de meter moni toring the output of the variable supply is calibrated in terms of RF ievel required to produce a given dc from the peak detector and hence peak RF power can be read from it directly CW power of course is correctly indicated also since the calibration is in terms of the peak voltage waveform 4 9 design of the peak detector is important factor in the reduction of errors The output capaci tor must be charged to the true peak of the waveform within the duration of the pulse though not necessari ly on t
41. t panel 5 11 Right and left Side Covers a Remove screws from side covers Top or bottom covers need not be removed to remove side covers to Meter a Remove top bottom right and left side covers b Remove all front panel knobs c Remove screws securing the RF IN and VIDEO OUT connectors d Remove all screws securing the side frames at the front of the instrument e Loosen all screws securing the side frames at the rear of the instrument f Spring side frames apart to allow front panel to drop forward NOTE The pilot light wires will restrict movement g Remove wires from meter terminals h Remove four nuts securing meter to sub panel and slide meter out of instrument 5 13 RF Detector Diode Fig 5 3 a Without removing the detector block from the instrument loosen the socket head set screw securing the diode with a No 2 035 hex wrench NOTE The printed circuit board must be removed to gain access to the diode set screw Model 89008 b Lift out the diode c Remove the bowed washer MPS from the bottom pin of the diode Figure 8 3 RF Detector Diode Assembly 1 When replacing the diode the cap must be on the cathode end of the diode The bowed washer from the original diode should be placed con cave side up on the anode end of the diode Fig 5 5 Diode Replacement It is important that the diode be pressed firmly in place before ti
42. u Nagoya City Tel 751 8545 KOREA American Trading Co Kotea Ltd Seoul P O Box 1103 112 35 Sokong Dong Jung ku Seoul Tel 3 7049 3 7613 LEBANON Constantin E Macridis Clemenceau Street Clemenceau Center Beirut Tet 220846 NETHERLANDS Hewlett Packard Benetux N V 23 Burg Roellstraat Amsterdam W Tel 020 13 28 98 NEW ZEALAND Sample Electronics N Z Ltd 8 Matipo Street Onehunga S E 5 Auckland Tel 565 361 NORWAY Morgenstierne amp Co A S ingeniofirma 6 Wessels Gate Oslo Tel 20 16 35 PAKISTAN Mushko amp Company Lid Oosman Chambers Victoria Road Karachi 3 West Pakistan Tel 54601 Mushko amp Company 110 Zitat Chambers 31 Jinnah Avenue Dacca East Pakistan Tel 80058 PANAMA Electronico Balboa S A 0 Box 4929 Panama City Tel 3 0833 PERU Fernando Ezeta B Av Petit Thouars 4719 Mira Flores Lima Tel 5 0346 PORTUGAL Telectra Rua Rodrigo da Fonseca 103 0 Box 2531 Lisbon 1 Tel 68 60 72 PUERTO RICO San Juan Electronics inc Ponce de Leon No 150 Stop 3 Pta de Tierra Sta San Juan Tel 725 3342 SPAIN Ingenieros Enrique Laretta 12 Madrid 16 Tel 235 43 44 5 SOUTH AFRICA F H Flanter amp Co Ply Ltd Roselia House Buitencingle Street Cape Town Tel 3 3817 F H Flanter amp Co Ltd 0 Box 200 Bramley 775 Pretoria Main Road Wynberg Transvaal Tel 40 5871 SWEDEN HP instrument AB Centraivagen 28 Soln
43. urce requirements are also met by readily available units 4 12 MONITOR OUTPUT 4 13 The 8900B includes a two stage emitter follower to provide an isolated monitor output for viewing and analyzing the demodulated output on an externally connected oscilloscope 4 14 The output bandwidth is 1 kHz to 7 MHz per mitting useful reproduction of a variety of waveforms This output may also be used for synchronizing the oscilloscope sweep circuitry with Function Switch in the MON CAL position Model 5900 Section Paragraphs 5 1 to 5 6 SECTION V MAINTENANCE 5 1 INTRODUCTION Specilicati is stated in Table 1 1 This check mav be used as part of an incoming quality 5 2 The 8900 Peak Power Calibrator is an easy inspection as a periodic operational chee repairs and or adjustments have been made The tosts can be performed without instrument cover removal instrument to maintain parts are accessible after removal ot the top bottom and side covers A plug in circuit board containing most of the instru ment circuitry is easily removal for the trouble shooting and repair 5 5 TEST EQUIPMENT REQUIRED 5 3 PERFORMANCE CHECKS 3 6 The test instruments required to make the performance checks are listed in Table 5 1 Test 5 4 The performance check in Table 5 2 verifies instruments other than those listed max be used whether or not the 8900 is operating within the provided their specifications equal or
44. vel should be greater than 200 mv P P for 20 mw input INPUT VSWR Input VSWR is measured with standard techniques The only precaution that should be observed is that the power level used in the test should be between 10 and 22 dbm The 50 ohm termination AT2 should be installed for the test Specification Input VSWR should be less than 1 1 25 MONITOR OUTPUT BANDWIDTH Connect the Pulse Generator to the 8900B RF IN connector and the oscilloscope hp 140A 1402A plug in to the MON OUT connector Apply a positive 2 volt pulse to the 8900B and measure the risetime on the oscilloscope Allowing for risetimes of pulse generator and oscilloscope the specification bandwidth of the 8900 7 MHz or greater will result in a 0 053 or less indicated risetime Substitute test equipment will require recalculating the allowable indicated risetime Section V Paragraphs 5 7 to 5 13 5 7 TROUBLESHOOTING AND REPAIR 5 8 8900 is relatively simple instrument For the purpose of troubleshooting the 8900B sche matic Fig 7 3 and the 8900B Print Circuit Board Fig 7 1 will have all necessary information includ ing voltages and resistance readings where applicable Voltmeter readings were made with an hp 410C 5 9 MECHANICAL DISASSEMBLY PROCEDURES 5 10 Top and Bottom Covers a Remove two screws at rear of instrument b Slide cover toward rear of instrument to disengage lip at fron
45. width of 1 kHz to 7 MHz in the amplifier produces useful reproductions for a variety of pulse shapes A typical frequency response of this circuit from the RF IN connector to the MON OUT connector is shown in Figure 3 9 2 az 77 omaz VIDEO SIGNAL FREQUENCY RELATIVE OUTPUT db Figure 3 9 Modulating Signal Frequency Response Model 8900B Section IV Paragraphs 4 1 to 4 9 OPERATION SECTION IV 4 1 DEFINITION OF PEAK POWER 4 2 The 8900B Peak Power Calibrator measures peak power as contrasted to average power measured by tional holometers and calorimeters The relationship between peak and average power may be defined as follows Pave X Duty Cycle 4 3 Duty cycle is the fractional time a pulsed source is turned on If the source were turned on 100 of the time the duty cycle would be 1 and peak power and average power would be equal Peak power then could be explained as the average power that would exist if the pulsed source were left on all the time It is not the instantaneous peak power envelope peak power that exists at the peak of the RF voltage waveform Assuming a sinusoidal CW source with an average power of 1 watt the peak power rating of the source is 1 watt also If the source is turned off 50 of the time the average power will be 1 2 watt whereas the peak power rating remains 1 watt 4 4 METHOD OF MEASUREMENT 4 5 Fora sinusoida
46. ws a typical chopper waveform The effect of contact Figure 3 7 Typical Chopper Waveform Section Paragraphs 3 38 to 3 39 bounce can be observed at points marked During the measurement of a double pulsed RF signal the oscilloscope waveform will appear as shown in Fig 3 8 EFFECT OF CONTACT BOUNCE Figure 3 8 Effect of Contact Bounce As a result of contact bounce the db reference line will not be a straight line When such a discontinuity resulting from contact bounce exists several methods can be used to avoid incorrect measurements The first method would be to synchronize the oscilloscope from the pulse video source A second method is shown in Fig 3 8 would be the use of a convenient oscilloscope graticule line as an extension of the correct dc reference line Another method would involve experimenting with the internal horizontal sweep when the syne from the pulse source is not 3 4 Model 89008 available and the triggering of the sweep to obtain a straight dc reference line 3 38 MONITOR OUTPUT 3 39 A two stage emitter follower isolating circuit connects the detector diode output to the rear panel Monitor Output connector MON OUT with an imped ance of 150 ohms in the MON CAL position of the function switch This makes the detector output available for waveform monitoring or other purposes such as external oscilloscope synchronization The band
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