HP-11096A-Manual-HF-Probe 电路图.pdf

OPERATING NOTE HIGH FREQUENCY PROBE 11096A HEWLETT PACKARD RadioFans.CN 收音机爱 好者资料库 Page 2 Model J J096A Table 1. Model I I 096A Specifications VOLTAGE RANGE: 0.25 V to 30 V. RESPONSE: Responds to peak value of input. Calibrated to read rms value of a sine wave input. AC TO DC TRANSFER ACCURACY: *Loaded with 10 megohms 10%. JOO kHz JOO MHz 500 MHz + 1 o C to + 30 C 0.5 dB 1.2 dB < 3 dB at 10 kHz and 700 MHz. INPUT IMPEDANCE: 4 megohms shunted by 3 pF max. The High Frequency Adapter adds I pF to the 3 pF specifications. MAXIMUM INPUT: 30 volts rms AC, 200 volts DC. CABLE CONNECTION: Shielded dual banana plug. Fits all standard 3/4 inch dual banana connectors. CABLE LENGTH: 4 ft. (12 J. 9 cm) minimum. WEIGHT: 3-1/2 oz net. ACCESSORIES SUPPLIED: Ground Lead Straight Tip Hook Tip High Frequency Adapter ACCESSORIES AVAILABLE: 11063A 50 Ohm Tee l 1536A 50 Ohm Tee 10218A BNC Adapter 10219A Type 874 Adapter I 0220A Microdot Adapter *The AC to DC Transfer Accuracy specification is with the I 1096A probe operating into a de voltmeter with input resistance of 10 MS110%. 1. DESCRIPTION. 2. The -hp-Model I 1096A High Frequency Probe converts a de voltmeter into a high frequency ac voltmeter. The probe is used f1;or ac voltage measurements of 0.25 volts to 30 volts over a fequency range of I 00 kHz to 500 MHz. 111e accuracy of measurement is 0.5 dB 100 kHz to 100 MHz and 1.2 dB to 500 MHz over a temperature range of + I o C to + 30 C. Additional specifications for the I I 096 A Probe are listed in Table 1. TI1e front cover shows the J l096A Probe with two compatible de voltmeters. Compatible de voltmeters are described in the following paragraph. 3. COMPATIBLE DC VOLTMETERS. 4. The -hp- I 1096A High Frequency Probe operates into any de voltmeter with an input resistance of IO megohms 10%. Directly compatible Hewlett-Packard voltmeters are listed below. The shjelded dual-banana plug on the probe permits direct connection to voltmeter input. -hp- Model 427 A Voltmeter. -hp-Model 3440A Digital Voltmeter with any plug in. -hp- Model 3439A Digital Voltmeter with any plug in. -hp- Model 3430A Digital Voltmeter. 5. OPERATION. 6. To extend the use of the -hp- Model l 1096A Probe three probe-tip accessories are supplied. The Straight Tip or Hook Tip with the ground lead can be used for measurements up to 100 MHz. For measurements above I 00 MHz the High Frequency Adapter permits the probe to be used with a 50 Ohm Tee. a BNC Adapter or other available accessories illustrated in Figure 1. 7. For proper operation the 11096A Probe must be connected to a de voltmeter with 10 fl!D 10% input resistance. The Probe may be used directly with any one of the voltmeters listed under Paragraph 4. NOTE To use the Probe with 100 IS1 de voltmeter. connect a 11 MS1 shunt resistor across the voltmeter input before attaching the Probe. 8. Since the l l096A Probe converts the ac input to a positive de voltage equivalent to the rms value of a sine wave, set the de voltmeter for a + VDC reading. Connect shielded dual banana plug to voltmeter de input with the GND Plug connected to the common input termjnal. Attach the desired probe tip to the probe body. and connect probe to circuit under test. NOTE The ground lead is required with Straight Tip or Hook Tip. The High Frequency Adapter does not require the ground lead when used with one of the accessories shown in Figure I . 9. USE 0 F TIPS. 10. The Hook Tip or Straight Tip can be used for measurements up to I 00 MHz. Above I 00 fllHz use the High Frequency Adapter with one of the accessories shown in Figure I. ( RadioFans.CN 收音机爱 好者资料库 ) ) Model 11096A ACCESSORIES AVAILABLE A 10220A MICRODOT ADAPTER 10218A BNC ADAPTER _, 10219A TYPE 874 ADAPTER 908A 50 OHM LOAD Page 3 I l Figure l . 1 l 096A Probe Accessories 11. MAXIMUM INPUT. J 2. The maximum input voltage with any probe tip is 30 volts rrns ac. or 200 volts de. An ac signal superimposed on a de level up to 200 volts may be measured if desired. WHEN MEASURING AN AC VOLT AGE SUPERIMPOSED ON A DC LEVEL, DO NOT CHANGE THE DC LEVEL BY MORE THAN 200 VOLTS WITH THE PROBE CONNECTED TO THE CIRCUIT U DER T EST ; OTHERWISE A VOLTAGE TRASIENT WILL DA.t1AGE THE DIODES WITHIN THE PROBE. 13. COMPATIBLE DC VOLTMETERS. 14. hp Model 427A. 15. With the 11096A Probe attached to -hp Model 427A Voltmeter the upper end of the 427 A fre4uency range is extended from l MHz to 500 MHz. Voltage levels from 0.25 volts to 30 volts can be measured with.in the specified accuracy of.the probe plus the de accuracy of the 427 A Voltmeter. 16. hp Model 3440A or 3439A. 17. With the I J096A Probe attached to the input of the -hp- Model 3440A, or 3439A, the magnitude of the ac signal being measured is displayed directly on the front panel digital display as a+ de voltage. When using the Probe with the 3440A or 3439A Digital Voltmeter any one of the available plug-in units may be used (-hp Model 344 I A thru 3446A). With the 3443A and 3444A Plug-in Units a 100 microvolt resolution is available on the 1000 mV range. RadioFans.CN 收音机爱 好者资料库 Page4 18. -hp-Model 3430A. 19. When using the Probe with the -hp- Model 3430A Four Digit Digital Voltmeter, a 60% overranging is available on all usable ranges. and a 1 mV resolution is available on the 1000 mV range. The magnitude of the ac signal being measured is displayed directly on the front panel digital display as a + de voltage. 20. THEORY OF OPERATION. 21. The 11096A High Frequency Probe is a peak detector with a voltage divider. The probe converts the ac input signal into a positive de voltage equal to the rms value of the input. The schematic for the 11096A Probe is shown in Figure 2. 22. The 11096A Probe includes a de blocking capacitor Cl, detection diode CR!, resistive divider RI , R3, CR2, R2. and Rin of the de voltmeter. Capacitor Cl charges through diode CRI during negative cycle of the input to produce a positive de voltage at junction of CR I and RI. This positive voltage is equal to the negative peak value below the de level of the input signal. The resistive voltage divider consisting of RI and R3 in series with CR2, R2 and I 0 MS1 in put resistance of the de voltmeter divides the peak voltage down to an rms value. A JO MS1 input resistance. Rin is required to provide the proper division ratio. 23. At low voltage levels the non-linearity of the detector diode characteristic curve is compensated by diode CR2. On the linear portion of the detector diode characteristic curve the division ratio of the voltage divider, (Rl , R3. CR2, R2 and Rin) remains constant, and results in 0.707 of the peak at the junction of R3 and CR2. On the non-linear portion of the diode curve. low voltage levels. diode CR2 compensates for non-linearity of CRJ by proportionally changing the division ratio of the divider. 24. Resistor R3 * is selected to calibrate the division ratio of the voltage divider. R3 * value range is SO kS1 to I 00 Hl. Refer to Paragraph 43 for selection of R3*. The value of R3* must result in an accuracy of 0% to+ 3% with an input of 3 volts at I MHz at room temperature. 25. MAINTENANCE. 26. PERFORMANCE CHECKS 27. The following Performance Checks verify proper operation of the 11096A High Frequency Probe over its entire frequency range. The performance checks compare the Model 11096A Probe with its published accuracy specification. These checks may be incorporated in periodic maintenance. post repair. and incoming inspection. Model 11096A Cl RI R3 IOOPF 825K 69.8K INPUT-1r-w.-.;.,._-o-, : CR2 CRI , Rin -3_._3- _ JOM Figure 2. Schematic and Component Location 28. The test equipment required for the performance checks is listed in Table 2. Table 2 includes the type of e qui pm en t required. critical specification. and the recommended model. If the model recommended is not available. equipment which meets or exceeds the required characteristics listed may be substituted. NOTE The following performance checks must be performed under an ambient temperature of + 10c to + 30c (+ so F to + 86F). 29. low Frequency Response Check. 30. This check verifies 11096A AC to DC Transfer Accuracy of 0.5 dB from I 00 kHz to I 0 MHz. 3 volts at 100 kHz is used as a reference to establish a reference level indication on test oscillator. 31. The following test equipment listed in Table 2 is required for the low frequency response check: Test Oscillator AC Voltmeter DC Voltmeter SO Ohm Feed-Thru Termination a. Connect a cable between test oscillator and digital voltmeter as illustrated in Figure 3. connection A. b. Set digital voltmeter to measure 3 volts ac. c. Set oscillator frequency to I 00 kHz. and adjust the output for 3.000 volt indication on digital voltmeter. ( ( ( ) ) Model I I 096A Page 5 d. Adjust the REF SET control on oscillator for a reference level indication on output monitor meter. Do not adjust the amplitude control to set the reference. Note the reference level indication. j. Observe voltmeter indication between 0.3 168 and 0.2832. e. Disconnect connection A; set digital voltmeter function to measure de, and connect the 11096A Probe to test oscillator output as illustrated in Figure 3. f. Observe de voltmeter indication between 3 .168 and 2.832 volts. NOTE The following steps verify AC to DC Transfer Accuracy with 0.95 and 0.3 volt input. g. Using test oscillator attenuator decrease output by 10 dB (0.95 volts). h. Observe voltmeter indication between l.006 and 0.894 volts (10 dB down from 3 volts). i. Using test oscillator attenuator, decrease output an additional 10 dB (0.3 volts). k. Return test oscillator attenuator to + 20 dB. (3 V output). l. Continue to check the Model 11096A Probe by repeating Steps f thru k with oscillator frequency set at 500 kHz, I MHz and I 0 MHz. Readjust oscillator amplitude to reference level indication established in Step d each time the frequency is changed. 32. High Frequency Response Check. 33. This check verifies I I096A AC to OC Transfer Accuracy of 1.2 dB from the I 00 MHz to 500 MHz. 34. The following test equipment listed in Table 2 is required for the high frequency response check: VHF Signal Generator DC Voltmeter Power Meter with Thermistor Mount 50 Ohm Tee Table 2. Test Equipment Required INSTRUMENT REQUIRED RECOMMENDED TYPE CHARACTERISTICS MODEL Test Oscillator Range: I 00 kHz to 10 MHz -hp- Model 652A Output: 3 volts to 0.3 volts Test Oscillator Flatness: Adjustable to 0.5% AC Voltmeter Voltage Range: 3 volts -hp- Model 3469B Frequency Range: 100 kHz Multimeter Accuracy: 0.5% of full scale DC Voltmeter Input Resistance: 10 Mfl 10% -hp- Model 34698 Voltage Range: 3, 1, and .3 volts full scale Accuracy: 0.5% of full scale Multimeter VHF Signal Generator Frequency Range: JOO MHz to 480 MHz -hp- Model 608E Output Level: I volt VHF Signal Generator Power Meter Frequency Range: 100 MHz to 480 MHz -hp-Model 432A/4 78A Power Range: 10 milliwatts Power Meter and Accuracy: 1 % Thermistor Mount 50 Ohm Tee Frequency Range: 100 MHz to 480 MHz -hp- Model I !063A VSWR: -<: , PROeE I -WJJP:!ll a:P=ll09=6= A=-=u-_ ) BNC ADAPTOR ll096.A.-B-338S hp 10 218A Figure 3. Low Frequency Response Check and Calibration a. Connect the test equipment to l I096A Probe as illustrated in Figure 4; set de voltmeter on 10 volt range. b. Set signal generator frequency to 100 MHz and adjust output for 10 milliwatt indication on the power meter. NOTE Monitor the power meter indication for a few minutes to assure that the signal generator has stabilized. c. Observe de voltmeter indication between 0.749 and 0.668 volts. Note: 0.707 volts= 10 milliwatts dissipated across 50 ohms. d. Repeat Step b with signal generator set at 200 MHz, 300 MHz, 400 MHz and 480 MHz. Ob- serve de voltmeter indication between 0.812 and 0.616 volts. 35. TROUBLESHOOTING. 36. If the I I 096A Probe is not within its published specifications or if the probe becomes inoperative, perform the procedures outlined in Paragraphs 37 and 39. The procedures outlined in Paragraphs 37 and 39 will isolate the trouble to a component or connection. Before performing any troubleshooting. an investigation should be made to ensure that the trouble is not a result of conditions external to the probe and de voltmeter in use. If a 50 ohm tee is being used with l 1096A Probe verify proper connection between the tee and the probe. 37. SUBSTITUTE VOLTMETER. 38. The first step in troubleshooting the l 1096A Probe is to verify that the trouble is in the probe and not the de voltmeter. This may be done by substituting another de voltmeter in place of the one that was connected to the probe when the trouble occurred. Any de voltmeter with 10 MQ input resistance may be used as a substitute. If available, any one of the Hewlett-Packard voltmeters listed in Paragraph 3 may be used as a substitute. 39. CHECK DIODES. 40. If the trouble appears to be in the probe, proceed with the following steps: a. Remove probe tip or High Frequency Adapter. b. Loosen set screw on the probe, and slide the probe housing toward the shield connector. NOTE The probe ground continuity is disconnected with printed circuit board outside of probe housing. c. Check diodes CRl and CR2 for open or short. Refer to Figure 2 for diode location. If the probe is completely inoperative (no voltage out) the trouble is most likely an open or shorted CR!. If the probe is within specified accuracy at 3 volts and above, but reads low with input below 3 volts the trouble is most likely a shorted CR2. If the probe reads high, 0.25 volts to 30 volts the trouble is most likely an opening in the CR2, R2 branch. NOTE It is not necessary to disconnect the diodes from the circuit when checking for open or short. d. If both diodes check good. check resistance from cathode of CRI to the appropriate banana plug on shield connector. Check continuity from cable crimp to GND banana plug on shield connector. ( ( ) ) ) Model 11096A Page 7 VHF SIGNAL GENERATOR hp608C MULTIMETER hp 34698 POWER METER hp 432A 11096ABE N MALE PROOE hpll09GA GNERAL RADIO nPE 874 TO TYPE N FEMALE THERMISTOR MOUNT hp478A Figure 4. High Frequency Response Check e. Visually check capacitor Cl for open lead or loose connection. 41. REPLACING DIODES. 42. Diodes CR I and CR2 may be replaced separately. However, if replacement of CR! causes too large of a change in frequency response, it may be necessary to replace CR! again. BOTH DIODES ARE HOUSED IN GLASS. ANY FORCE APPLIED TO THE DIODE BODY COULD CAUSE BREAKAGE. 43. CALIBRATION AFTER REPAIR. 44. After replacing the diodes verify proper value of Resistor R3* by performing the following steps: a. Perform Steps a thru e outlined under Paragraph 29. b. Set oscillator frequency to I MHz. and readjust oscillator amplitude to reference level established in Step d. Paragraph 29. c. Observe de voltmete