HP 774D User's Manual
Contents
1. PROCEDURE a Connect equipment as shown in Figure 11 b Set signal source for 1 kHz squarewave modulated CW signal at the frequency in question c Set SWR Meter to HIGH XTAL input impedance and obtain a reading d Peak the reading on SWR Meter either by adjusting modulation frequency of signal source or frequency control on SWR Meter e Set any convenient reference on SWR Meter 40 dB NORMAL scale f Slide slotted line carriage to a minimum SWR indication maximum meter deflection as near the center of the slotted line as possible g Switch SWR Meter to EXPAND scale 0 dB range and set to 1 0 reading on SWR scale h Slide slotted line carriage to a maximum SWR indication minimum needle indication and read meter If reading is not 1 15 or less try different low SWR terminations and try testing other couplers before rejecting the coupler under test Page 16 HP 774D 775D PERFORMANCE TESTS cont d COUPLING SPECIFICATION Accuracy of coupling mean coupling within 0 5 dB of 20 dB each secondary arm Maximum coupling variation 1 dB 50 ohm terminations DESCRIPTION Coupling will be tested using a leveled power source with a barretter on a swept frequency basis A barretter is used because of the frequency range and its wider square law range X Y RECORDER RECORDER OUT SWEEP OSCILLATOR ete PENLIFT LOW PASS FILTER LOW SWR mere TERMINATION Se DIRECTIONAL COUPLER CRYSTA2. SWR is measured by measuring return loss with a leveled source As with any reflectometer first calibration is performed by reflecting all of the signal Then the 774D 775D under test is connected and the SWR measured From a reflectometer calculator obtainable free from any Hewlett Packard office listed at the end of this note we find that an SWR of 1 15 equals a return loss of 23 1 dB However with the ambiguity of 40 dB couplers we must test for a return loss of 24 5 dB or greater to be sure of an SWR of 1 15 a Connect the equipment as at in Figure 8 OSCILLOSCOPE I WITH SWEPT FREQUENCY INDICATOR SWEEP OSCILLATOR CRYSTAL lt 0 OPEN LOW PASS a DETECTOR FILER TERMINATION LOW SWR m DIRECTIONAL COUPLER ERARIO DETECTOR ti COUPLER TERMINATION UNDER TEST Figure 8 Swept Frequency Primary Line SWR Test Setup EQUIPMENT Sweep Oscillator 4 4 HP Model 8850B with HP Model 83522A Low Pass Filter saa a GAGE SS G HP Model 860A B Crystal Detector 2 ve ae a ss EG Ae He Bcd oS HP Model 482A Directional Coupler vo s ce Gow we aw HP Model 77 4D 775D see note above Oscilloscope 22 a verre re 2 04000 HP Model T41T with 1416A Termination 3 L 2 2 22 2 6 ee ee a 44044 HP Model 909A Opt 012 HP 774D 775D Page 11 PERFORMANCE TESTS cont d EE PROCEDURE Calibration b To calibrate proceed as follows 1 Set
3. with the reflectometer calculator obtainable free from any Hewlett Packard office a list of these offices is at the end of this operating note Error also results from multiple reflections or mismatch losses of the components of the reflecto meter system The ambiguity introduced by this error can also be calculated with the reflectometer calculator mentioned above For more information on reflectometer systems refer to Hewlett Packard Application Note 65 obtainable free from any Hewlett Packard office Power Measurement The 774D and 775D may also be used for measuring power as shown in Figure 6 Here the coupler samples primary line power and a coaxial thermistor mount is used as a power detecting device The coupler can also be used for measuring peak power up to 10 kW provided average power remains below the rating of the coupler 50 watts and the sampled pulses are attenuated to the power handling capability of the thermistor mount When monitoring power with these couplers keep in mind that the output power is the coupling 20 dB nominally ABOVE the power sampled at the auxiliary port For very precise work the insertion loss of the coupler attenuation of primary line must be subtracted from the calculated output power 7 TT ss NY Np i lm Miri VIT 0 064 MIN 0 066 MAX 0 207 MIN 0 210 MAX 0 314 MIN 0 316 MAX Figure 2 Dimensions of Type N Connectors HP 774D 775D SWEPT FREQUENCY
4. Area instrument Repair Center 1491 S Manhattan Ave Fullerton CA 92631 GEORGIA 450 Interstate N Parkway Atlanta GA 30348 ILLINOIS 5201 Tollview Dr Rolling Meadows IL 60008 NEW JERSEY W 120 Century Rd Paramus NJ 07652 AUSTRALIA Hewlett Packard Australia Ltd 31 41 Joseph Street Blackburn Victoria 3130 HP Part No 00774 90009 6877 Goreway Drive Mississauga Ontario Canada L4V 1M8 amp ITALY Hewlett Packard Italiana S p A Via G Di Vittorio 9 20063 Cernusco Sul Naviglio MI FRANCE Hewlett Packard France Quartier de Courtaboeuf Boite Postale No 6 F 91401 Orsay Cedex GERMAN FEDERAL REPUBLIC Hewlett Packard GmbH Vertriebszentrale Frankfurt Bernerstrasse 117 Postfach 560 140 D 6000 Frankfurt 56 HEWLETT GP PACKARD Van Heuven Doedhartlaan 121 P O Box 667 NL Amstelveen 1134 UNITED KINGDOM Hewlett Packard Ltd King Street Lane GB Winnersh Wokingham Berks RG11 SAR AFRICA ASIA CENTRAL AND SOUTH AMERICA Hewlett Packard Intercontinental 3200 Hillview Avenue Palo Alto CA 94304 Printed in U S A
5. INDICATOR SWEEP OSCILLATOR ETTER TINIE ESLER VERT IN CETHI LETT y oO Oo o CRYSTAL 7740 775 E Caa UNKNOWN CRYSTAL ti DETECTOR Figure 3 Typical Reflectometry Setup SWEEP REFERENCE SERIES SWEEP OSCILLATOR Page 5 VECTOR VOLTMETER VHF OSCILLATOR amp DOUBLER uw STRETCHER UNKNOWN ree la aon an av 90 a 7740 7750 TERMINATION fi TEE Figure 4 Setup for Impedance Measurement NETWORK ANALYZER HARMONIC FREQUENCY CONVERTER LOWPASS FILTER 774D 775d CONNECT P UNKNOWN HERE STRETCHER Figure 5 Network Analyzer in Reflectometer Setup Page 6 432A POWER METER 478A 8478A COAXIAL SIGNAL POWER SENSOR SOURCE CL 1 MW TO I WATT 909A COAXIAL TERMINATION Figure 6 Power Measuring Setup The couplers can be used not only for power measurement but for system adjustment for best power transfer as well This adjustment can be made easily with the setups of Figures 3 4 or 5 This adjustment ean also be made with only a power meter and a coupler Alternately connect the thermistor mount first to the incident auxiliary arm and then to the reflected auxiliary arm Con nect first as shown in Figure 6 Take a reading then interchange the thermistor mount and the load and take another reading Adjust the system for a maximum incident reflected power ratio Power Leveling The 774D and 775D can also be used for power leveling
6. T Model 8491A Option 010 PROCEDURE a Connect the equipment as at in Figure 13 b To calibrate the setup proceed as follows 1 Set sweep oscillator to sweep over the band of interest with automatic sweep and squarewave modulation 2 Set sweep oscillator for leveled output over the frequency band of interest 3 Set SWR Meter to high impedance crystal input and to 30 dB or more sensitive range HP 774D 775D Page 19 PERFORMANCE TESTS cont d 4 Set sweep oscillator to lowest frequency in band with manual sweep 5 Adjust sweep oscillator RF output for a reading on SWR Meter and adjust sweep oscillator internal squarewave frequency control for a peak reading on the SWR Meter 6 Adjust reading on SWR Meter to be 0 3 dB for 774D or 0 4 dB for 775D this reading is maximum insertion loss limit for coupler being tested 7 Manually sweep frequency and adjust X Y Recorder controls to keep pen holder on paper 8 Set X Y Recorder pen down and record a trace This is the insertion loss limit trace 9 Set SWR Meter to 0 0 dB at lowest frequency in band and run a trace This trace is the 0 dB baseline Measurement c To make a measurement proceed as follows 1 Connect the coupler under test as shown at in Figure 13 9 Run a trace This is the insertion loss trace This trace should fall between the baseline and calibration traces Table 3 Performance Test Record Model 77 D Dual Directional Coupl
7. for end and test other half of coupler Page 18 HP 774D 775D PERFORMANCE TESTS cont d ALLEY He 0 INSERTION LOSS NOTE To test a 774D use another good 774D as the SPECIFICATION 774D lt 0 3 dB 775D lt 0 4dB directional coupler in Figure 13 To test a 775D DESCRIPTION use a good 775D Insertion loss will be measured on a swept frequency basis using an SWR Meter and an X Y Recorder For calibration two traces will be run a 0 dB trace and an insertion loss limit trace The coupler under test will then be inserted and a test trace run The test trace should lie between the two calibration traces X Y RECORDER FN RECORDER HTA Tv SWEEP OSCILLATOR METER PENLIFT OG 8 IN og p MOTOL p CRYSTAL SWEEP ALC RF a oT ha p i ATTENUATOR LOW PASS TERMINA i E HTERMINATION O an E ae e ea DIRECTIONAL carseat PECTIN Sinton rd COUPLER GER TERMINATION TEST Figure 13 Insertion Loss Test Setup EQUIPMENT Sweep Oscillator L ou 22224220 HP Model 8850B with HP Model 83522A Low Pass Filter 2 ae se GA K GN Gr G HP Model 360A B Crystal Detector 2 2 2 2 2 2 2 2 eee a HP Model 423A Directional Coupler 2 sea ae sk a Sw _ HP Model 7 74D 775D see note above Termination 3 a age ce Se sk EE SNE GE HP Model 909A Opt 012 SWR Meter DS de Me GN EG Re TE Model 415E X Y Recorder fo Ae Ge EE Ge DE ae HP Model 7035B Attenuator Be og BENN SEG PE EA Bs
8. if a single directional coupler is not avail able Connect as shown in the left half of Figure 3 Terminate the unused auxiliary arm with a 50 ohm termination PERFORMANCE TESTS Use the following procedure for initial inspection performance testing or whenever the coupler per HP 774D 775D formance is suspected Table 2 lists the recom mended test equipment Other equipment may be substituted provided its specifications equal or exceed the specifications listed under Critical Specifications The coupler should be tested on a swept frequency basis to assure that there are no out of specification narrow frequency bands The performance test should be done in the order listed For instructions refer to the Performance Test Table 3 Performance Test Record provides a place to record the results IMPORTANT NOTE When a low SWR termination is specified in these tests the accuracy of the measurement is dependent largely on the quality of this termination Always use the best termination available If any of these tests do not meet specifications consider the ambiguity in troduced by the SWR of the termination before rejecting the coupler Try several ter minations before rejecting the coupler Sliding load test techniques at single frequen cies are not practical due to the low frequen cies involved For these reasons you are urged to test the coupler as soon as it is received with the lowest SWR termination available If
9. sweep oscillator to sweep over the band of interest with automatic sweep 2 Set sweep oscillator for leveled output 3 With 5 dB em or more sensitive setting on the oscilloscope obtain a trace Mark this trace with a grease pencil This is the calibration line Measurement To measure the primary line SWR proceed as follows 1 Connect the dual directional coupler under test as shown at 2 in Figure 8 2 Increase the gain on the swept frequency indicator by 24 5 dB 3 Observe the trace The test trace should be below the calibration line at all frequencies If so the coupler is in specifications without question at all frequencies If the test trace is above the calibration line the coupler may or may not be within specifications directivity signal may be adding To determine if the coupler is within specifications test at the frequency in question on a fixed frequency basis The fixed frequency test follows d If the coupler is within specifications turn coupler end for end and repeat the test on the opposite port Page 12 HP 774D 775D PERFORMANCE TESTS cont d Fixed Frequency Test DESCRIPTION This fixed frequency SWR test should be used when the coupler does not meet the swept frequency test or when the equipment for swept frequency testing is not available The AED used is the standard method of measuring SWR with a slotted line and SWR Meter SIGNAL SOURCE ue METER LOW PASS FI
10. the pen up throughout the band Make sure trace will stay on recorder adjusting X Y recorder position and gain controls if necessary 6 Put the recorder pen down and run a trace This is the calibration trace Measurement c To make a measurement proceed as follows 1 Connect the termination as shown in in Figure 7 Note that this termination must have an SWR lt 1 01 Do NOT use adapters which will increase SWR with this termination If adapters are used the results will be degraded 2 Remove the 40 dB attenuator and connect the crystal detector directly to the auxiliary output arm 3 Run a trace on the X Y Recorder If the trace stays below the calibration trace the directivity signal plus the reflection signal from the load is 40 dB down If not the coupler could still be good depending upon the termination SWR For a termination with a SWR of 1 005 and a 40 dB directivity signal the resultant could be as low as 38 dB At Hewlett Packard selected loads are used to ensure that the coupler is within specifications See IMPORTANT NOTE in performance test introduction Turn the coupler end for end and repeat the test on the other half of the coupler Page 10 HP 774D 775D PERFORMANCE TESTS cont d PRIMARY LINE SWR SPECIFICATION Note To test a 774D use another good 774D as the lt 1 15 774D and 775D directional coupler in Figure 8 To test a 775D use a good 775D Swept Frequency Test DESCRIPTION
11. 0 mV in Low SWR Frequency band of interest H02 909A type N male ea SWR 1 01 at frequency tested H03 909A type N eae Coaxial 50 ohms Termination 3 Frequency band of interest 909A Opt 012 SWR 1 05 Coaxial 50 ohms Dual Directional Frequency band of interest 774D or 775D Coupler Directivity gt 40 dB Nominal coupling 20 dB Crystal Detector Frequency band of interest 423A Sensitivity gt 4 mV u W Oscilloscope Vertical Sensitivity 0 5 dB cm 141T 1416A Swept Frequency Accuracy 0 02 dB dB Indicator Barretter Frequency band of interest PRD 627AM Response 0 1 dB octave Adapter Male to mal type N 1250 0778 UG 57B U Adapter Female to female type N 1250 0777 UG 29B U Signal Source Frequency frequency of interest Any sweep oscillator Internal AM 1 kHz squarewave listed above operated in Power output gt 10 mW CW Slotted Line Frequency band of interest Residual SWR lt 1 04 Impedance 50 ohms Page 8 HP 774D 775D PERFORMANCE TESTS DIRECTIVITY SPECIFICATION 240 dB 774D and 775D DESCRIPTION Directivity of a coupler is the ratio of power at the auxiliary port when coupler is in forward direction to power at the auxiliary port when coupler is in reverse direction coupler perfectly terminated each time and same power The 774D 775D should be swept frequency tested to be sure that there are no narrow band out of specification points that would be missed with fixed frequency testing These c
12. 775D Page 13 PERFORMANCE TESTS cont d AUXILIARY ARM SWR NOTE SPECIFICATION lt 1 2 774D and 775D To test a 774D use another good 774D as the directional coupler in Figure 10 To test a 775D Swept Frequency Test use a good 775D DESCRIPTION Same as for primary line SWR SWEEP OSCILLOSCOPE OSCILLATOR WITH SWEPT FREQUENCY INDICATOR i 4 HORIZ VERT IN IN TERMINATION TERMINATION By CRYSTAL t C open FILTER mm l UNDER p 2 TEST CRYSTAL amp DIRECTIONAL I COUPLER TERMINATION DETECTOR Figure 10 Swept Frequency Auxiliary Arm SWR Test Setup EQUIPMENT Sweep Oscillator 4 4 HP Model 8850B with HP Model 83522A Low Pass Filter A aie he ole armen te AE SEE ee ee ee Bote ae HP Model 360A B Crystal Detector 2 2 2 2222 ee e e HP Model 423A Directional Coupler 2 2 1 2 222242 HP Model 774D 775D see note above Oscilloscope 2 2 2 eee ee ee ee ee ee HP Model 141T with 1416A Termination 3 22 2 22 2 ee ee ee ee et ee HP Model 909 Option 012 PROCEDURE a Connect the equipment as shown at in Figure 10 Calibration b To calibrate proceed as follows 1 Set the sweep oscillator to sweep over the band of interest with automatic sweep 2 Set sweep oscillator for leveled output 3 With 5 dB cm or more sensitive setting on the oscilloscope obtain a trace Mark this trace with a grease pencil This is the calibration trace Measur
13. HP 774D 775 eR HP 7740 7750 DUAL DIRECTIONAL COUPLERS ENTEN KRD SENDE FONEM DAMA E EREET SANS BEAST ALLA LL EN OMANOE NOVI V PT EP Ae ON MANNA 2 FAKG RANGE 7740 DUAL D 215 450 MHz p Aar SOQ ESS TEST PORT f HEWLETT PACKARD JULY 1986 OGLL OvLL dH Page 2 DESCRIPTION The Hewlett Packard Model 774D and 775D Dual Directional Couplers are three port passive devices for use in 7 mm 50 ohm systems A coupler is essentially a device for sampling power flowing in one direction in a transmission line Since no coupler is perfect some power flowing in the opposite unwanted direction is also sampled The rejection of power flowing in the unwanted direc tion is called directivity and is the most important specification of a directional coupler These coup lers have 40 dB directivity Another specification is the forward coupling attenuation usually called just coupling which is the fractional amount of power transferred in the wanted direction These couplers have a nominal 20 dB of coupling These terms are defined in Figure 1 Figure 1 also shows a typical coupling curve This curve is not a specifica tion The specifications are shown in Table 1 Table 1 Specifications HP 774D HP 775D Frequency Range 215 450 MHz 450 940 MHz Minimum Directivity 40 dB Coupling Attenuation 20 dB nominal each secondary arm Accuracy of Coupling Mean coupling level within 0 5 dB
14. L COUPLER UNDER DETECTOR F TEST TERMINATION Figure 12 Coupling Test Setup EQUIPMENT Sweep Oscillator 2 2 4 HP Model 8350B with HP Model 83522A Low Pass Filter aS 2 SE ee SH HP Model 360A B Directional Coupler sak se KE Sk sk RES HP Model 774D for testing 774D HP Model 775D for testing 775D Crystal Detectors 2 D ET NE EE G p HP Model 423A Terminations 2 eck HP Model 909A Opt 012 Low SWR Termination HP Model 909A H02 909A A type N ne H03 909A type N female Attenuator hoon meee ae oe HP Model 8491A B Barretter fe es a DE SE Se GN ES KEN Gode es He Se PRD 627 AM SWR Meter pe ch Pe a EE GE k EG ee ees ae 2 EP Model 415E X Y Recorder Dr igs ae hn the tea Se OE a ge ae Da HP Model 70058 HP 774D 775D Page 17 PERFORMANCE TESTS cont d PROCEDURE a Connect the equipment as shown in in Figure 12 Calibration b To calibrate the setup proceed as follows 1 2 Set sweep oscillator to sweep band with squarewave modulation Set sweep oscillator for leveled output Set SWR Meter to the low 4 5 mA bolometer input range and for 30 dB sensitivity range Set sweep oscillator for manual sweep and adjust sweep oscillator internal squarewave modulation frequency for maximum reading on SWR Meter Set sweep oscillator RF out for a reading of 0 dB at some frequency lowest frequency in band is convenient Use this same frequenc
15. LTER COUPLER 10 dB TERMINATION ATTENUATOR SLOTTED LINE UNDER M PR TE LOW SWR iir TERMINATION TERMINATION Figure 9 Fixed Frequency Primary Line SWR Test Setup EQUIPMENT Signal Source 2 1 1 es HP Model 8350B with HP Model 83522A Attenuator HTG Ge GR GE ol ie a 4 HP Model 8491A B Slotted Line ake ed sk EA GO eg HP Model 805C SWR Meter et Sah a NG rte ee vb SB ily Uy Moe ae eee fs es HP Model 415E Terminations 2 5 HP Model 909 Option 012 Low SWR Termination HP Model HO2 909A type N male H038 909A type N female PROCEDURE a Connect the equipment as shown in Figure 9 b Set signal source for a 1 kHz squarewave modulated signal at the frequency in question c Set SWR Meter to HIGH XTAL input impedance and obtain a reading d Peak reading by adjusting modulation frequency of signal source or frequency control of SWR Meter e Set any convenient reference on the SWR Meter 40 dB NORMAL scale f Slide slotted line carriage to a minimum SWR indication maximum meter deflection as near the center of the slotted line as possible g Switch SWR Meter to EXPAND scale 0 dB range and set to 1 0 reading on SWR scale h Slide slotted line carriage to a maximum SWR indication minimum needle indication and read meter If reading is not 1 15 or less try different low SWR terminations and try testing other couplers before rejecting the coupler under test HP 774D
16. ctrical Check The electrical performance should be verified as soon as possible after receipt Refer to the perfor mance test for further information Claim for Damage If a coupler is mechanically damaged or fails to meet specifications upon receipt notify the carrier and your nearest Hewlett Packard Office immedi ately a list of Hewlett Packard offices is at the end of this operating note Retain the shipping carton and the padding material for the carrier s inspec tion REPACKAGING FOR SHIPMENT Using Original Type Packaging Containers and materials like those used in factory packaging can be obtained through Hewlett Packard offices listed at the end of this operating note If the coupler is being returned to Hewlett Packard for servicing attach a tag indicating the type of service required return address model number and serial number Also mark the container FRAGILE to assure careful handling In any correspondence refer to the instrument by model number and serial number HP 774D 775D Using Other Packaging The following general instructions should be used for repackaging with commercially available materials a Wrap the coupler in heavy paper or plastic if shipping to a Hewlett Packard office attach a tag indicating the type of service required return address model number and serial number b Use a strong shipping container A double wall carton made of 350 pound test material is ad
17. each secondary arm of 20 dB Max Coupling Variation 1 dB Max Primary Line SWR 1 15 50 ohm terminations Max Auxiliary Arm SWR 1 20 50 ohm terminations Primary Line Power Handling Capacity 50 watts average 10 kW peak Primary Line Insertion Loss lt 0 3 dB lt 0 4 dB Primary Line Connectors Type N connectors one male and one female Auxiliary Arm Connectors Type N female connectors Size in 9 1 16 x 3 1 8 x 1 3 4 mm 230 x 79 x 45 Weight net 3 lb 1 4 kg i Measured with Hewlett Packard H02 909A male or HO3 909A female termination 2 Compatible with connectors whose dimensions conform to MiL C 39012 or MIL C 71 HP 774D 775D Port Terminology The two directly connected ports on opposite ends of the coupler are called the primary line ports The coupled ports on each side are called the auxiliary ports Coupling is in the direction of the arrows on the nameplate These coupled ports are called auxiliary line ports Accessories Available Two shorting connectors Hewlett Packard Model 11511A Type N female short and Model 11512A Type N male short are available as accessories INITIAL INSPECTION Mechanical Check If damage to the shipping carton is evident ask that the carrier s agent be present when the coupler is unpacked Inspect the parts for mechanical damage such as scratches or dents Also check the cushioning material for signs of severe stress compacting Ele
18. ement c To measure the auxiliary arm SWR proceed as follows 1 Connect the 774D or 775D under test as shown at in Figure 10 2 Increase the gain on the swept frequency indicator by 21 9 dB 3 Observe the test trace It should be below the calibration trace at all frequencies If so the coupler is within specifications at all frequencies If test trace is above calibration trace coupler may or may not be within specifications Check with following fixed frequency test d If coupler is within specifications turn end for end and repeat measurement on other port kv Ev Page 14 HP 774D 775D PERFORMANCE TESTS cont d Fixed Frequency Test DESCRIPTION This fixed frequency SWR test should be used when the coupler does not meet the swept frequency test or when the equipment for swept frequency testing is not available The setup used is the standard method of measuring SWR with a slotted line and SWR meter SIGNAL SOURCE SWR METER E LI TERMINATION Figure 11 Fixed Frequency Auxiliary Arm SWR Test Setup EQUIPMENT Signal Source 2 rer 224 HP Model 8350B with HP Model 83522A Slotted Line pas Syk SAS SEE SEE HP Model 805C SWR Meter si on i we ce ee ee we RO ee a EG ee amp BR Model 415E Terminations 3 222 arr ve ee eee ee ee ee o HP Model 909A Attenuation 2 ae eh a ee GS en a GO eS G GG So HIP Model S492 4 8 HP 774D 775D Page 15 PERFORMANCE TESTS cont d
19. equate c Use enough shock absorbing material 3 to 4 inch layer around all sides of the coupler to provide firm cushion and prevent movement inside the carton d Seal the shipping carton securely e Mark the shipping carton FRAGILE to assure careful handling PRIMARY Page 3 OPERATION Precautions Connectors The type N connectors used on these couplers will mate with all other type N connectors whose dimensions conform to MIL C 71B and MIL C 39012 Do NOT mate with the male type N connector on other 774D s with serials below 3119 or 775D s with serials below 3141 see caution below l CAUTION Do NOT mate with 0 071 diameter pin male connectors Damage may result When installing be sure auxiliary equipment sup ports its own weight The coupler particularly the connectors is not designed to carry weight Do Not Drop Do NOT drop the coupler While the coupler probably will not break it can be jarred out of adjustment and the connectors can be damaged COUPLER PERFECTLY PRIMARY TERMINATED LINE LINE INPUT INPUT Po AUXILIARY ARM COUPLING COUPLING 10 log primary line input P4 2p AUXILIARY ARM auxiliary output Pop P4 or 10 log 10 Pap The coupling varies with frequency so the following terms must be defined DIRECTIVITY COUPLING NOMINAL MEAN FREQUENCY F DIRECTIVITY 10 log p dB R Terms for the other auxiliary arm may be defined i
20. er Serial Number Directivity mm _ dB gt 40 dB SWR Primary Line ___________ 22 dB return loss Auxiliary Arm gt 19 9 dB return loss Coupling Mean coupling 0B 20 0 5 dB Maximum coupling variation mm dB 1 dB Insertion Loss 774D m AB lt 0 3 dB 775D mem dB lt 0 4 dB CERTIFICATION Hewlett Pack 3 mba certifies that this product met its published specifications at the time of shipment from the b Tetor Hewl Packare dfurther certifies that its calibration measurements are traceable tothe United States National Bureau of Standard fo 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 designated by HP for use with an ins
21. n a similar manner Figure 1 HP 774D 775D Coupler Terminology Page 4 Ambient Conditions Do not heat cycle this coup ler during use or storage Keep coupler near room temperature 25 C Coupler will stand relative humidity of 95 but will be affected by condensa tion keep at room temperature Signal Flow Signal flow is indicated in Figure 1 Coupling is indicated by arrows These couplers are bi directional signal may go through the coupler in either direction APPLICATIONS Introduction These couplers are usually used in a reflectometer Figures 3 4 5 and 6 illustrate typical setups Note that a line stretcher or a longer length of cable must be used with vector voltmeters or network analyzers to balance the two signal paths in the coupler for zero phase reference Complementary Equipment Figures 3 4 5 and 6 show Hewlett Packard model numbers for equip ment suitable for use with the 774D 775D couplers Error Analysis There are certain errors present in all reflectometer systems Usually the most signifi cant error is that caused by the directivity of the directional coupler The magnitude of this error can be measured accurately over the frequency band see Directivity Check under PERFOR MANCE TEST Once the directivity is known the JACK FEMALE 0 204 MIN 0 207 MAX 0 063 MIN 0 066 MAX 0 316 MIN 0 320 MAX HP 774D 775D ambiguity of any measurement can be determined
22. ouplers will be tested on a swept frequency basis with a standard reflectometer setup X Y RECORDER RECORDER PENLIFT SWEEP OSCILLATOR CRYSTAL H DETECTOR ga LOW PASS FILTER h CT OPEN i COUPLER DETECTOR ty UNDER LOW SWR TEST e G spm NATION Figure 7 Swept Frequency Directivity Test Setup EQUIPMENT Sweep Oscillator LL 2 2 22222242 HP Model 8350B with HP Model 83522A Low pass Filter 4 ak s s ee SE a we we HP Model 360A B SWR Meter din bbe ANS sein i et Se Ayer cdo BGA DN Ra BSE cw Je EP Model 415E Crystal Detector ge Be gr awe we Jie Tihs Se and ER ES AR Model 423A X Y Recorder Bee oao FR re SANE OG EEG oh ee Wi we o HP Model 20205 Attenuator er Ar dt HP Model 8491A Low SWR Termination ahs ape BSE HP Model HO2 909A type N male HO3 909A type N female HP 774D 775D Page 9 PERFORMANCE TESTS cont d PROCEDURE Calibration a Connect equipment as shown at Aa in Figure 7 b To calibrate the reflectometer proceed as follows 1 Set the sweep oscillator to sweep over the band of interest with automatic sweep 2 Set sweep oscillator for leveled squarewave modulated output 3 Set sweep oscillator for manual sweep 4 Set the SWR Meter to 30 dB or more sensitive range vary the sweep oscillator RF power to get a reading and peak the reading with sweep oscillator internal squarewave frequency control 5 With manual sweep move the X Y Recorder with
23. results better than 38 dB directivity are obtained assume the coupler is good Keep the load separate and use only for this testing If the coupler is suspected in the future test for any change in the incoming inspection test results If you get the same results assume the coupler is good If the results change send the coupler to Hewlett Packard for repair Repair Do not attempt to repair these couplers Their high directivity characteristics depend upon the pre cision with which they are assembled If a coupler does not meet specifications or is damaged it should be returned to Hewlett Packard for repair HP 774D 775D i Page 7 Table 2 Recommended Test Equipment The following equipment is recommended for testing Other equipment may be used provided its specifications equal or exceed the specifications listed under Critical Specifications Critical Specifications HP Model No Sweep Oscillator Frequency band of interest HP 8350B with 835224 Internal AM 1 kHz squarewave aa plug in Power output gt 10 mW k Power leveling V input Low pass filter Rejects second harmonics 360A for 774D Rejection gt 40 dB 360B for 775D SWR Meter Frequency compatible with sweep oscillator square 415B E wave modulation Accuracy lt 0 1 dB error 10 dB Attenuator Attenuation 10 dB 40 dB 8491A B Opt 010 10 dB Frequency Response 0 5 dB Opt 040 40 dB X Y Recorder Impedance 200K ohms V 7035B Sensitivity gt 5
24. trument 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 HP SHALL NOT 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 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 NO CALIFORNIA San Francisco Area Hewlett Packard Canada Ltd NETHERLANDS Hewlett Packard Benelux N V 333 Logue Ave Mt View CA 94043 SO CALIFORNIA Los Angeles
25. y for all subsequent level settings Manually sweep frequency range with X Y Recorder pen up and adjust recorder to keep pen holder in upper portion of graph but on the paper We will now run three traces 1 dB apart to calibrate the vertical scale Set reading on SWR Meter to 0 dB at lowest frequency Run a trace Label this trace 19 dB Set reading on SWR Meter to 2 dB at lowest HCAMENEY Set pen down and run a trace Label this trace 21 dB Set reading on SWR Meter to 1 dB at lowest frequency Set pen down and run a trace Label this trace 20 dB We now have three traces 1 dB apart Do not change conditions from this setting We will insert the coupler and measure the deviation from this setting Measurement c To make a measurement proceed as follows 1 Connect the coupler under test as shown at 2 in coupling test setup Figure 12 This will insert the nominal 20 dB down coupling attenuation in the signal path Set the RANGE switch on the SWR Meter to the 50 dB range This increases the gain back to the calibration conditions Run a trace This is the coupling curve or how the coupler varies from exactly 20 dB of attenuation Referring to definitions in Figure 1 measure accuracy of coupling mean coupling and the maximum coupling variation by using the distance between any two adjacent calibration traces on a vertical line as a 1 dB scale Specification limits are given at the beginning of the test Turn coupler end
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