422A Crystal Detector Operating and Service Manual
Contents
1. 7 SIGNAL SOURCE For reflectometer measure ment systems the RF signal must be square wave modulated with 1 kHz An economical source of modulated signals in K or R band is obtained by using a broadband frequency doubler driven by a RF source with built in provision for 1 kHz square wave modu lation Figure 2 shows sucha combination for band and Table 2 lists equipment required to obtain K or R band signals with HP Models 938A and 940A Frequency Doubler Sets The filter in the Models 938A 940A passes the second harmonic of the input frequency rejects the ourth harmonic and most of the third The stop band in the Model 938A is from 31 to 80 GHz when using the low end of the band 18 to 20 6 GHz input to 938A of 9 10 3 GHz the presence of third harmonics may make it necessary to use a ilter with 27 to 30 9 GHz stop band The stop band in the Model 940A is from 46 to 120 GHz when using the low end of the band 26 5 to 30 6 GHz input to 940A of 13 25 to 15 3 GHz the presence of third harmonics may makeit necessary use a filter with a 39 75 to 45 9 GHz stop band Page 3 HP Model 626A SHF Signal Generator or Model 8690 8694 Sweep Oscillator HP Model 938A Frequency Doubler Set HP Model MX292B M to X Adapter 11504A Flexguide K band Waveguide Figure 2 Using HP Model 938A Frequency Doubler Set to Obtain Modulated K Band Signais Table 2 K and R Band Signal Sources2. Frequency Required Signal Source with Mod Capabilities Freq GHz Adapter Required Waveguide Link Frequency Doubler Set Output Freq GHz 10 13 25 MX292B 11504A 20 26 5 Flexguide 8694B 9 12 4 MX292B 11504A 18 24 8 8695A 12 4 15 11503A 24 8 30 4 626 13 25 15 5 MP292B 11503 940 26 5 31 NP292A Flexguide 628A 15 0 20 NP292A 11503A 30 40 8695A 13 25 18 NP292A 11503A 26 5 36 4 Model 626A SHF Signal Generator Model 8690 8695 Sweep Oscillator HP Model 938A Frequency Doubler Set HP Model 292 M to X Adapter HP 11504A Flexguide K Band Waveguide HP K382A Variable Attenuator Waveguide filter under test HP Model 422A Crystal Detector and Load Resistor HP Model 24 Waveguide Stand HP Model X25 Waveguide Clamp HP Model 415B E Standing Wave Indicator Figure 3 Typical K Band Setup for Measuring Insertion Loss 8 MEASUREMENT OF RELATIVE POWER LEVELS 9 GENERAL 10 When sensitivity is important the Model 422A is also useful for relative power measurements such as measuring insertion loss or monitoring power level where the power is sampled witha directional coupler A typical K band setup for measuring insertion loss is shown in Figure 3 Device under measurement is a waveguide filter The reference reading is made with
3. 422 AND SERVICE MANUAL 422A _ CRYSTAL DETECTOR Printed AUGUST 1979 gt PACKARD dH 2 SECTION GENERAL INFORMATION 1 The Model 422A Crystal Detector Figure 1 isa broadband device which includes a crystal diode a waveguide mount designed to match approximately the impedance of the crystal diode anda resistor Option 002 only whichloads the crystal for maximum square law range Lossy elements in the mount re duce the SWR of the device Model 422A detectors are available for use inthe K 18 to 26 5 GHz and R 26 5 to 40 GHz bands and canbe obtained in matched pairs 2 For optimum square law response a separately contained Load Resistor is supplied with Model 422A Option 002 Crystal Detectors see Figure 1 Each load resistance is factory matched to a specific Model 422A and permits conversion from optimum square law response with the load to optimum sensitivity without the load Each Load Resistor is identified by a serial number marked on its name plate which is iden tical to the serial number of the Model 422A to which it is matched If you have more than one Load Resistor always check that you are using the proper Load Res istor for the 422A in use 3 Model 422A detectors are available in matched pairs for dual channel applications such as reflec tometer systems Each detector of a pair meets the
4. Table 1 SENSITIVITY Typically 0 3 mV CW FREQUENCY RESPONSE i2 MAXIMUM SWR Model 422 2 5 422 3 0 MAXIMUM INPUT 100 mW peak or average OUTPUT POLARITY Negative SQUARE LAW RESPONSE Furnished with matched load resistor for Optimum square law character istics at 24 C 75 F less than 0 5 dB variation from square law from low level up to 50 mV peak output working into an external load gt 75K for optimum square law response Frequency Model Range Model 422A Model 422A Crystal Detector and Load Resistor Figure 1 same specifications as single units and the frequency response difference between the detectors of a pair totals no more than 1 dB for levels below approxi mately 0 05 mW Each Model 422A of a matched pair is identified by an identical serial number marked on its name plate 4 The rectified output appears at BNC connector the RF input is a waveguide cover flange For use in systems using circular flanges a contact flange adapter can be supplied on order with Model 422A see Table 1 The detector in the Model 422A is a developed crystal diode replacement crystals are supplied mounted in the required special waveguide holder Specifications LOAD RESISTOR Load Resistor value selected Mates with Equiv Flange Waveguide Size Length JAN Type FLANGE Cover type OPTION 001 Matched pair of units fitted wi
5. the filter out of the line and the Model K382A Variable Attenuator set for at least 10 dB the setting of the attenuator as well as the reading of the Model 415B E are noted Then the filter is inserted in the line and the attenuator adjusted to again obtain the reference reading on the Model 415B E Difference between the first and second settings of the attenuator is the insertion loss of the filter Characteristics required of equipment used in a setup like that shown in Figure 3 are discussed below Model 422A 11 EQUIPMENT CONSIDERATIONS 12 INDICATOR For applications where signal level is low it is convenient to use an indicator such as the HP Model 415B E Standing Wave Indicator whichis high gain voltmeter with square law calibration Maximum sensitivity is obtained from the Model 422A by setting the Model 415B E input selector switch at the XTAL 200K Q position 13 SIGNAL SOURCE Since the Model 415B E is an audio device the RF must be modulated at the rate of the frequency to which the Model 415B E input filter is tuned generally this is 1 kHz Thus the signal source must have either an internal source of modu lating voltage or an input for modulating voltage Signal sources such as those discussedin Paragraph 7 are suitable 14 For most measurements level of the signal into the Model 422A should be low enough that crystal response is in the square law range see Figure 4 With RF input signals of 18 dBm pe
6. Drive Van Heuven Doedhartlaan 121 Mt View 94043 Mississauga Ontario Box 667 80 CALIFORNIA Los Angeles Area Canada 1M8 NL Amatelveen 1134 5400 West Rosecrans Blvd Lawndale Ch i260 Italiana S p A GEORGIA UNITED KINGDOM Via G Di Vittorio 9 450 Interstate Parkway Hewlett Packard Ltd 20063 Cernusco Atlanta 80348 Nadale D King Street Lane ILLINOIS GB Winnersh Wokingham 5201 Tollview Dr FRANCE Bers RG11 Rolling Meadows IL 60008 Hewlett Packard France NEW JERSEY Quartier de Courtaboeuf W 120 Century Rd Boite Postale No 6 AFRICA ASIA CENTRAL AND Paramus NJ 07652 F 91401 Orsay Cedex SOUTH AMERICA AUSTRALIA GERMAN FEDERAL REPUBLIC Hewlett Packard Intercontinental Hewlett Packard Australia Ltd Hewlett Packard GmbH 3200 Hillview Avenue 31 41 Joseph Street Vertriebszentrale Frankfurt Palo Alto CA 94304 Blackburn Victoria 3130 Bernerstrasse 117 Postfach 560 140 D 6000 Frankfurt 56 TEMENS 5 PACKARD MANUAL PART NO 00422 90009 Microfiche Part No 00422 90011 Printed in U S A up 5
7. PUT Figure 6 Exploded View of Model 422A Crystal Detector 21 REPLACEMENT OF PARTS 22 Procedure for replacing the BNC connector on the detector mount is covered in Paragraph 24 and replac ing those the Load Resistor in Paragraph 27 For additional maintenance information contact the Hewlett Packard Company of your local HP field office 23 Stock numbers for replaceable parts are given in Table 3 Section V 24 REPLACING BNC CONNECTOR 25 TOOLS REQUIRED Needle point soldering iron Wire cutters Flat file 4 Tweezers 26 PROCEDURE Parts mentioned in the following procedure are identified in Figures 6 and 7 a Remove BNC connector type UG 88 U mating male connector may be used to loosen the female b Unsolder contact spring soldered to center conductor lead c Prepare replacement BNC connector 1 Cut center conductor lead to approximately 1 32 inch see Figure 7 6 SPRING Figure 7 Cutting BNC Connector Center Conductor Lead to Accommodate Contact Spring 2 With flat file smooth end of lead wipe off burr with tweezers or similar metal instrument d Slip contact spring over center conductor lead and solder CAUTION Use solder sparingly or it will creep back on spring Solder on spring destroys its usefulness and solder is diffucult to remove from spring e Let spring cool and then screw the connecto
8. ak or less error due to deviation from square law typically will be less than a half dB when the Model 422A is operated with its selected Load Resistor With RF input signals of about 18 dBm to 3 dBm and loading resistor at tached error due to deviation from square law will be no higher than 1 dB 1 As a precaution against operating the crystal outside the square law region use only the 30 40 50 or 60 ranges of the Model 415 2 The level of the RF into the Model 422A can be determined approximately from reading the Model 415B E With the input selector at XTAL 200K 3 mV into the Model 415B E will give a reading of at least 0 onthe 30 range 100 IN 0 01 DETECTED OUTPUT 50 40 30 20 10 INPUT POWER IN 0 4 Figure 4 Square Law Characteristics at 20 C of Typical 422A Crystal Model 422A 3 The following typical Model 415B reading can be used as a rough guide to determine whether the signal into the Model 422A is low enough to operate the crystal within its square law range The reading was made with the Load Resistor installed in the Model 422A the Model 415B E GAIN control set at maximum full clockwise and the input selector at XTAL 200K 0 With a RF signal of 23 dBm into the Model 422A the Model 415B E indi cated approximately 2 on the 40 range 15 ATTENUATOR A variable precision att
9. eavy paper b Unsolder resistor Solder resistor to new BNC d Let resistor cool and then check resistance from male BNC pin through resistor Replace lockwasher and male 30 REPLACING FEMALE BNC CONNECTOR To remove andinstalla BNC connector BNC wrench or use a male BNC connector as a wrench a Remove BNC connector b Unsolder contact spring Prepare replacement BNC connector 1 Cut center conductor lead to approximately 1 32 inch 2 With flat file smooth end of lead wipe off burr with tweezers or similar metal instrument d Slip contact spring over center conductor lead and solder CAUTION Use solder sparingly or it will creep back on spring Solder on spring destroys its usefulness and solder is difficult to remove from spring e Let contact spring cool and then screw the connector into the mount RESISTOR LOCK WASHER CONTACT SPRING LOCK WASHER MALE BNC FEMALE BNC SOLDER THESE POINTS HOUSING Figure 8 Load Resistor Cutaway View 422 31 REPLACEMENT OF CRYSTAL HOLDER 32 Parts referred to in the following procedure are identified in Figure 6 To replace the crystal holder proceed as follows a Remove the four screws from the wave guide input section b Remove waveguide input section c Remove the crystal holder 9 Check that the contact to the BNC connector center conductor is bright and clean If not bu
10. enuator such as the Model 382A attenuator is requiredfor the measurement method briefly described in Para graph 10 To reduce error due to source mismatch connect the attenuator between source and system and set the attenuator for at least 10 dB 16 HARMONIC FREQUENCY COMPARISON MEASUREMENTS 17 The Model 422A is suitable for use as a mixer in harmonic frequency comparison measurements See HP Application Note 2 SECTION CIRCUIT 18 Arrangement of the Model 422A and equivalent circuit is indicated in Figure 5 The crystal may be considered as a voltage generator with an internal resistance of from approximately to 20K ohms and a shunt capacitance of approximately pF The Load Resistor is selected to obtain the maximum range of square law operation with inputs of up to half milli watt average VIDEO LOAD OPTION 02 VIDEO LOAD OPTION 02 R VIDEO ae RESISTOR OUTPUT ENA SELECTED OPTIMUM 1 SQUARE LAW RESPONSE LOSSY DIELECTRIC 422A CIRCUIT Figure 5 Arrangement of 422A and Equivalent Circuit SECTION IV MAINTENANCE 19 PREVENTIVE MAINTENANCE 20 Protect the face of the coupling flange from damage Any scoring or burring of the mating sur faces causes discontinuity The resulting increase in SWR degrades performance Page 5 BNC OUTPUT CONTACT SPRING HOLDER INSERT WAVEGUIDE IN
11. nated by HP for use with an instrument will execute its programming instructions when properly installed on that instrument HP does not warrant that the operation of the instrument or software or firmware will be uninterrupted or error free LIMITATION OF WARRANTY The foregoing warranty shall not apply to defects resulting from improper or inadequate maintenance by Buyer Buyer supplied software or interfacing unauthorized modification or misuse operation outside of the environmental specifications for the product or improper site preparation or maintenance NO OTHER WARRANTY IS EXPRESSED OR IMPLIED HP SPECIFICALLY DISCLAIMS THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE EXCLUSIVE REMEDIES THE REMEDIES PROVIDED HEREIN ARE BUYER S SOLE AND EXCLUSIVE REMEDIES HPSHALLNOT BE LIABLE FOR ANY DIRECT INDIRECT SPECIAL INCIDENTAL OR CONSEQUENTIAL DAMAGES WHETHER BASED ON CONTRACT TORT OR ANY OTHER LEGAL THEORY ASSISTANCE Product maintenance agreements and other customer assistance agreements are available for Hewlett Packard products HEWLETT PACKARD SERVICE OFFICES 1 To obtain servicing information contact the nearest Hewlett Packard Sales and Service Office in HP Catalog or contact the nearest regional office listed below UNITED STATES CANADA NETHERLANDS CALIFORNIA San Francisco Hewlett Packard Canada Ltd Hewlett Packard Benelux 333 Logue Ave 6877 Goreway
12. onnector male BNC includes rubber ring 1250 0045 5 Connector female BNC includes 1250 0083 1 1250 0083 1 1250 0251 5 lockwasher Spring contact 5000 0234 9 5000 0234 1 5000 0234 9 Screw 4 40 x 5 8 fillister stainless steel 4 TQ 4 TQ 00422 60007 00422 60008 0 00422 20004 2 TQ Total quantity used in instrument CERTIFICATION Hewlett Packard Company certifies that this product met its published specifications at the time of shipment from the factory Hewlett Packard further certifies that its calibration measurements are traceable to the United States National Bureau of Standards to the extent allowed by the Bureau s calibration facility and to the calibration facilities of other International Standards Organization members WARRANTY This Hewlett Packard instrument product is warranted against defects in material and workmanship for a period of one year from date of shipment During the warranty period Hewlett Packard Company will at its option either repair or replace products which prove to be defective For warranty service or repair this product must be returned to a service facility designated by HP Buyer shall prepay shipping charges to HP and HP shall pay shipping charges to return the product to Buyer However Buyer shall pay all shipping charges duties and taxes for products returned to HP from another country HP warrants that its software and firmware desig
13. r into the mount CHECKING After the new BNC is installed check for alignment of the leaf spring and crystal lead by measuring the resistance across the BNC connector CAUTION Use a low current ohmmeter such as the HP Model 410B 1 Set the ohmmeter for the RX100 or higher range Connect ohmimeter lead to the BNC center conductor and the other to the BNC shell 2 Take a reading Reverse the leads and take another reading a Normal There will be a reading of a few hundred ohms in one direction and tens of thousands of ohms in the other b No reading The leaf spring is not making contact with the crystal lead Remove the BNC connector a mating male connector may be used to loosen the female stretch the leaf spring reinstall the BNC and again measure the resistance c Low reading If the reading is very low the leaf spring probably is touching the side of the mount Remove the BNC adjust the spring so it will center in the opening re install the BNC and again measure the resistance Model 422A 27 REPLACEMENT OF BNC CONNECTORS 28 Parts referred to inthe following procedures are identified in Figures 7 and 8 29 REPLACING MALE BNC CONNECTOR a Remove male BNC connector from housing To remove BNC use 3 8 inch open end wrench and hold the housing either in a vise or with gas pliers Before putting pliers on protect the housing of the Load Res istor with material such as h
14. rnish with fine sandpaper and wipe clean with cloth e Install the new crystal holder with the polyiron insert facing toward the wave guide input f Replace waveguide input section and secure with the four screws SECTION V REPLACEABLE PARTS 33 INTRODUCTION 34 This section contains information on ordering replacement parts for the Model 422A and Load Resistor In addition to identifying the part Table Page 7 3 lists the manufacturer s name and the total quantity TQ used in the instrument 35 ORDERING INFORMATION 36 To order a replacement part address order or inquiry either to your nearest Hewlett Packard field office see lists on following page or to CUSTOMER SERVICE CENTER Hewlett Packard Company 333 Logue Ave Mt View California 94040 or in Western Europe to HP GmbH Technisches Buero Boblingen Herrenbergerstrasse 110 D 7030 Boblingen Wurttemberg 37 Specify the following for each part and serial number of the device b HP Part number and Check Digit CD Description 38 To order a part not listed in Table 3 give a complete description of the part Table 3 Replaceable Parts Model 422A and Load Resistor Description HP Part Number K422A R422A Load Resistor CD Crystal Kit Loaded Crystal Kit Matched pair with square law load Polyiron Disk 00422 60005 7 00422 60006 8 00422 20004 2 C
15. th square law load Frequency response character istics exclusive of basic sensitivity track within 41 dB for power levels less than approximately 0 05 mW OPTION 02 Furnished with matched load resistor for optimum square law characteristics at 24 C 75 F 2 lt 0 5 dB variation from square lawfrom low level up to 50 mV peak output working into an external load gt 75K Sensitivity typically 0 1 mV uW CONNECTORS Model 422A BNC female Load Resistor BNC one male one female K422A3 18 26 5 GHz 0 500 x 0 250 in 12 x 64 mm 0 360 x 0 220 9 6 UG595 U 26 5 40 0 GHz UG599 U 1 As read on a meter which is calibrated for use with square law detectors 2 Read a meter such as one of the 415 or 416 series which is calibrated for Square law detectors 3 Circular lange adapters K band UG425 U 11515A R band UG318 U 11516A 422 SECTION OPERATING INSTRUCTIONS 5 REFLECTOMETER MEASUREMENTS 6 PROCEDURES Improved techniques make it possible to use non matched crystal detectors in reflectometer setups The new techniques are de scribed the Hewlett Packard Journal Vol 12 No 4 copy of which may be obtained irom the Hewlett Packard Company on request Use of matched crystal detectors in a reflectometer system is described in the HP Journal Vol 6 1 2
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