HP-Service-Note-382A-1A 电路图.pdf

SERVICE NOTE 8 MODELS G382A, C382A, J382A, H382A, X382A AND P382A BROADBAND PRECISION WAVEGUIDE VARIABLE ATTENUATOR CALIBRATION AND ALIGNMENT PROCEDLTRES This Service Note describes an improved method for calibration and alignment of your Model 382A Broadband Precision Waveguide Variable Attenuator. The procedure incorporates swept frequency tech- niques to arrive at more accurate and more complete Cali bration. The swept frequency technique provides rapid “com- plete frequency range” testing. If possible errors exist in your attenuator*, this technique will easily spot them. The point-by-point method (spot checking across the frequency band) may overlook these errors such as resonances, holes, or other deviations from normal. Using the swept frequency technique elimi- nates any chance of missing these deviatinna - HP- MOOEL 680 SERIES SWEEP OSCILLATOR. 382A-1A These procedures cover measurement of attenuator standing wave ratio, measurement of insertion loss, and dial calibration. Equipment required varies with the test desired. See figures 1 through3 which show setups for individ- ual tests. * The attenuation, in decibels, of your Model 382A is directly proportional to the angle to which the re- sistive metal film card in the center section is ro- tated with respect to the end section cards. Since the attenuator obeys a precise mathematical law, the po- sition of the dial with respect to the angular rotation of the center section is the controlling factor of cali- bration accuracy. Precise methods for achieving this alignment are outlined in these Service Notes. -HP-MODEL 416A r RATIO METER. PROCEDURE. - - -. Figure 1. Test Setup for Measuring Standing Wave Ratio 3 distribution abcefg 01074-2 COMPLETE COVERAGE IN H E W L E T T p A C K A R D C 0 M p A N y CL?CTRON!lC WEASUPING EQUIPWENT 1501 P A G E MILL R O A D R U E O U V I E U X B I L L A R D N O . 1 P A L 0 A L T O , C A L I F O R N I A , U . S . A . G E N E V A , S W I T Z E R L A N D CAB LE: “H EWPAC K” DAVENPORT 6 - 7 00 0 CABLE: HEWPACKSA” TEL. NO. (0221 26.43.36 PRlNTED IN “.*.I. RadioFans.CN 收音机爱 好者资料库 Page 2 382A-lA w ,- -HP- MODE L 880 SERIES np- MDDEL 4 1 6 / 9mEPOSCILLATM). -HP-YODELS 421A OR 4850 NOTE: IF 40SD IS USED AN AC 60 K BARRETTER MATCHIN TRANSFORMER IS REQUIRED R BIASING BARRETTER. -HP- MOOEL 382A UNDER TEST. -HP- YODELS14 8 1 u-u*zm YOVINQ LOAD Figure 2. Test Setup for Measuring Insertion (Fixed) Loss STANDING WAVE RATIO (SWR) TEST PROCEDURE 1) Set up test equipment to agree with figure 1. 2) Adjust signal source for 1000 cps square wave modulated RF output. 3) Calibrate reflectometer system to: p = 100% for frequency range of Model 382A p = Reflection coefficient (with short applied to Point A). 4) Remove the Model 920A Adjustable Short from Point A. Set 382A under test tominimum attenuation. Terminate one port with a Model 914A Moving Load. Connect the other port to Point A. (see figure 1.) 5) Measure Reflection Coefficient, p , of the Model 382A under test throughout its frequency range. p must be less than 7% which corresponds to an SWR of 1.151. 6) Repeat step 5 for attenuator dial readings of 10 db, 20 db, 30 db, 40 db, 50 db, and MAX. 7) Reverse ends of Model 382A under test and re- p?at steps 4, 5, and 6. NOTE: If SWR is. out of specification, check for warped, broken, burned, or wrinkled resistive cards. Check for silver paink on cards or foreign material in rotary choke joints. L) IG 4 MEASUREMENT OF INSERTION LOSS 8) Set up test equipment as shown in figure 2. 9) Set signal source for 1000 cps square wave modu- lated RF output. Adjust signal source to highest fre- quency of Model 382A frequency range. Adjust the SET TO FULL SCALE control of the416Afor a meter reading of “2” on the db scale. Measure and record the variations in 416A readings versus frequency at the quarter points of the frequency band. For example: For the “X” band the check points would be 8.2, 9.25, 10.3, 11.35, and 12.4 gc (gigacycles). Note: Use minus (-) notation for up-scale variations, and (+) for down scale variations. 10) Insert the 382A under test into the system at Point A and set it to minimum attenuation as indicated by the 416A. Measure and record as in step 9 the vari- ation in 416A readings versus frequency at the quarter points. 11)Add the data in step 9 to the data in step 10. This value will be the insertion loss of the 382A under test. This figure must be less than 1.0 db. NOTE: If insertion loss is high, checkcard alignment. The three cards should be in the same plane. Also, check the rotary choke joints for leakage, as a com- mon cause for high insertion loss is poorly painted joints on the ends of the center barrel. 4 01074-1 RadioFans.CN 收音机爱 好者资料库 “ “ y 382A-1A Page 3 DIAL CALIBRATION 12) Set up test equipment as sh 13) Set signal source to mid-band I frequency range. Adjust for 1000 modulated RF output. 14) Tune the 485B to obtain maximui 415B/C. Set 382A under test to the at approximately 48 db on the atteni the Model 382A padding attenuator 1 db on the 50 db range of the Mode: NOTE: If a double peak in maximum i the resistive center card has been emulsion side reversed. Refer to Se. steps 1 through 21 for correct insta 15)Check the variation from 1 db of dot on the other side of MAX. 16)If adjustment is necessary, loo and the dial hub clamping screw in 1 just the dial so the difference in pa the two dots is less than 0.2 db c 415B/C. This aligns the dial to th of the center section. Tighten cal setscrews and recheck. 17) Check for backlash at a dial reac ( $ 3 Model 382A. NOTE: When backlash is in excel to figure 4 and make the following a backlash after each adjustment. e c 01074-2 Figur own in figure 3. joint of Model 382A cps square wave m indication on the dot which appears uator dial. Adjust for a reference of 1415B/C. nttenuation occurs installed with the mice No:e 382A-2, llation procedure. the corresponding sen the setscrews the dial hub. Adj- lwer level between is indicated by the e angular position p screw and allen ling of 50 db on the ss of 0.2 db, refer djustments. Check A. Check the position of the backed off approximately 1/4 the bearing. B. Adjust the worm gear tens minimize backlash. C. Adjust the worm gear thru minimize backlash. 18) Set the 382A padding atter 382A under test to “0” (zerc attenuator for a reference of : of the 415B/C. 19) Set the 382A under test to 10 to the 50 db range. Read and r 415B/C. The difference betwe reference set in step 18 is the results when 10 db is set o 20) Switch the 415B/C to 40 db padding attenuator to return to reference obtained in step 19. 21) Repeat steps 19 and 20 for dii 30 db, 40 db and 50 db. The E total error and must not exceec ever is greater. 22)Repeat steps 18 through 2 of the band. NOTE: The detector mount mi frequency. -HP- MOOU 680 SERIES SWEEP OSCILLATOR. - HP- YODEL 382A UNDER TEST. e 3. Test Setup for Calibrating Model 382A Ring nut. It should be turn from snug against ion adjustment screw to st adjustment screw to iuator to MAX. Set the ). Adjust the padding 1 db on the 40 db range db. Switch the 415B/C ecord indication on the en this reading and the actual attenuation that n the 382A under test. range. Adjust the 382A the deviation from the nl calibrations of 20 db, :rror recorded will be i l 2.v0 orO.l db which- 1 at the quarter points ast be retuned at each - HP- MODEL 415B1C STANOlNG WAVE INDICATOR. Y BARRETTER MOUNT. RadioFans.CN 收音机爱 好者资料库 Page 4 L a w 01074-1