GIG_8651A_8652A_srv 电路图.pdf

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1、R e g i s t r a r : B S I , C e r t i fi c a ti o n F M 3 4 2 2 6 R e g i s t e r e d 0 4 J u n e 1 9 9 6 ? A m e n d e d 1 0 S e p t e m b e r 2 0 0 1 ISO 9001 Certified Product Certified Process Giga-tronics Incorporated 4650 Norris Canyon Road, San Ramon, California 94583 925.328.4650/800.726.444

2、2/925.328.4700 (Fax) Customer Service: 800.444.2878/925.328.4702 (Fax) Publication 32089, Rev. A4, February 2002 Series 8650A Universal Power Meters Service Manual RadioFans.CN 收音机爱 好者资料库 WARRANTY Giga-tronics Series 8650A instruments are warranted against defective materials and workmanship for two

3、 years from date of shipment. Giga-tronics will at its option repair or replace products that are proven defective during the warranty period. This warranty DOES NOT cover damage resulting from improper use, nor workmanship other than Giga-tronics service. There is no implied warranty of fitness for

4、 a particular purpose, nor is Giga-tronics liable for any consequential damages. Specification and price change privileges are reserved by Giga-tronics. MODEL NUMBERS The series 8650A includes two models: The single-channel Model 8561A and the dual-channel Model 8652A. Apart from the number of senso

5、rs they support, the two models are identical. Both models are referred to in this manual by the general term 8650A, except where it is necessary to make a distinction between the models. All technical data and specifications in this publication are subject to change without prior notice and do not

6、represent a change without prior notice and do not represent a commitment on the part of Giga-tronics Incorporated. 2002 Giga-tronics Incorporated. All rights reserved. Printed in the USA. RadioFans.CN 收音机爱 好者资料库 DECLARATION OF CONFORMITY RadioFans.CN 收音机爱 好者资料库 Preparation for Reshipment Follow the

7、se instructions if it is necessary to return the product to the factory. To protect the instrument during reshipment, use the best packaging materials available. If possible use the original shipping container. If this is not possible, a strong carton or a wooden box should be used. Wrap the instrum

8、ent in heavy paper or plastic before placing it in the shipping container. Completely fill the areas on all sides of the instrument with packaging material. Take extra precautions to protect the front and rear panels. Seal the package with strong tape or metal bands. Mark the outside of the package

9、“FRAGILE DELICATE INSTRUMENT”. If corresponding with the factory or local Giga-tronics sales office regarding reshipment, please reference the full model number and serial number. If the instrument is being reshipped for repair, enclose all available pertinent data regarding the problem that has bee

10、n found. NOTE: If you are returning an instrument to Giga-tronics for service, first contact Giga-tronics Customer Service at 800.444.2878 or Fax at 925.328.4702 so that a return authorization number can be assigned. You can also contact Customer Service via our e-mail address . Manual 32089, Rev. A

11、, December 2000i Table of Contents About This Manual .v Conventions . vii Record of Manual Changes . ix 1 Specifications 1.1 Introduction .1-1 1.1.1 Environmental Requirements .1-1 1.2 Safety Precautions .1-1 1.3 8650A Universal Power Meter Specifications.1-2 2 Adjustments 80 dB MAP/PAP; 60 dB BAP D

12、isplay Resolution:User-selective from 1 dB to 0.001 dB in Log mode and from 1 to 4 digits of display resolution in Linear mode. Measurement Modes:CW, Peak, MAP, BAP, PAP Averaging:User-selective auto-averaging or manual, 1 to 512 readings. Timed averaging from 20 ms to 20 seconds. Automatic noise co

13、mpensation in auto-averaging mode. dB Rel and Offset:Allows both relative and offset readings. Power display can be offset by -99.999 dB to +99.999 dB to account for external loss/ gain. Configuration Storage Registers:Up to 20 front panel setups plus a last instrument state at power- down to be sto

14、red and recalled from non-volatile memory. Power Measurements and Display Configuration:Any four of the following channel configurations simultaneously: A, B, A/B, B/A, A-B, B-A, DLYA, DLYB, Min/Max, Bar Graph/ Peaking Meter, Peak Hold, Crest Factor, or Mean see Section 2.2.1 of the Operation Manual

15、 for instructions on how to set the GPIB mode and address). 2.Connect the GPIB controller to the GPIB Port on the rear of the 8650A. 3.Send the command: *IDN? (*IDN? is the IEEE 488.2 Common ID query. When addressed to talk after receiving the com- mand, the 8650A will output a string that identifie

16、s itself as Model 8651A or 8652A.) 4.Display the response on the controller. This completes the performance verification test for the 8650A Universal Power Meter and its sensors. If the instrument has performed as described in this chapter, it is correctly calibrated and within specifications. Adjus

17、tments 1 = field rep; 2 = service center; 3 = customer site) Password flag: 0 for disable, 1 for enable 2.5.2Load Sensor Data to Edit Buffer and Write from Buffer to Sensor EEPROM TEST EEPROM A|B READ TEST EEPROM A|B WRITE n where n = password number in range of 0 to 999999 Series 8650A Universal Po

18、wer Meters 2-16Publication 32089, Rev. A4, February 2002 2.5.3Cal Factor Table & Frequency Query EEPROM A|B CALF? Response: whole cal factor table sorted by frequency EEPROM A|B FREQ? Response:whole frequency table sorted by frequency 2.5.4Standard Frequency Correction Factor Table & Standard Freque

19、ncies Table TEST EEPROM A|B CALFST d* TEST EEPROM A|B CALFST? TEST EEPROM A|B FREQST? 2.5.5Standard Start Frequency, Standard Frequency Increment, Number of Standard Frequencies, Number of Special Frequencies TEST EEPROM A|B CALFR d d n n Query:TEST EEPROM A|B CALFR? Syntax Examples NI 488.2 wrt$ =

20、“TEST EEPROM A CALFR 2E9,1E9,17,1” ibwrt pwrmtr%, wrt$ mNI VISA wrt$= “TEST EEPROM A CALFR 2E9,1E9,17,1” stat = viWrite(sesn, wrt$, Len(wrt$), retCount) Description:This command sets the lowest frequency in the normal frequency correction table, the frequency increment, the number of normal frequenc

21、y correction points and the number of special frequency correction points. 2.5.6Special Frequency Correction Factor Table & Special Frequencies Table TEST EEPROM A|B CALFSP d* TEST EEPROM A|B CALFSP? TEST EEPROM A|B FREQSP d* TEST EEPROM A|B FREQSP? Adjustments & Performance Tests Publication 32089,

22、 Rev. A4, February 20022-17 2.5.7Cal Factor Write Example NI 488.2 Syntax wrt$ = “TEST EEPROM A READ” ibwrt pwrmtr%, wrt$ spfrqcf = “0.00” 50 MHz cal factor stanFreq = “2.00,3.00,4.00,5.00,6.00,7.00,8.00,9.00,10.00,11.00,12.00,13.00,14.00,15.00,16.00,17.00,18.00” standard frequency cal factors wrt$

23、= “test eeprom a calfsp” + spfrqcf ibwrt pwrmtr%, wrt$load special frequency cal factor into edit buffer wrt$ = “test eeprom a calfst” + stanfreq ibwrt pwrmtr%, wrt$load standard frequency cal factors into edit buffer wrt$ = “test eeprom a write 0 ibwrt pwrmtr%, wrt$write cal factors from edit buffe

24、r to sensor EEPROM 2.5.8Linearity Correction Factors TEST EEPROM A|B CORR dX6 Correction factor range: -99 to 99 TEST EEPROM A|B CORR? 2.5.9Start/Stop Frequency, Power (dBm), Video R+ and R- TEST EEPROM A|B SPEC dX5 TEST EEPROM A|B SPEC? 2.5.10Sensor Temperature Compensation (807XXA Only) TEST EEPRO

25、M A|B TC CLR|LO|MID|HI TEST EEPROM A|B TC CUR?|LO?|MID?|HI? Returns 9 values. Use the “CUR?” to query last temperature data after a calibration. Series 8650A Universal Power Meters 2-18Publication 32089, Rev. A4, February 2002 Manual 32089, Rev. A, December 20003-1 3 Theory of Operation1 3.18650A Po

26、wer Meter Theory of Operation The power meter is basically a specialized microvoltmeter which measures the RF detector diodes voltage. A patented calibration system linearizes the diode sensors while EEPROM stored data (in the sensors) is used to apply frequency related correction factors. 3.1.1Gene

27、ral Theory The 8650 power meter is used with a dual Schottky diode detector sensor module. It measures RF power up to 40 GHz depending on which sensor is used. All Schottky diodes operate in the square law region below 30 dBm. This means they give a DC voltage output proportional to the RF input vol

28、tage squared (P=V3/R). The detector is a good 50 termination. At higher power levels the diodes no longer give a linear output directly proportional to input power. The detected voltage is measured with a known RF power from 30 dBm to +20 dBm. The built in calibrator generates this accurate RF power

29、 at 50 MHz and optionally at 1 GHz. This data is used to correct the meter readings. The detector sensors are measured over their frequency range during manufacturing. Frequency correction factors are stored in EEPROM in each sensor. When the front panel (or GPIB) FREQ switch is pressed and the sign

30、al frequency is entered, the frequency correction factor is automatically calculated in the displayed reading. Figure 3-1: 8650A Meter Block Diagram DSP Main Processor ADCX8X8X8Mux DAC Trim Gain Select Front Panel/ Display IEEE 488 Single Channel Meter Shown In RS-232 Calibrator Chopper X1 X8 X64 Ch

31、opper FPGA Series 8650A Universal Power Meters 3-2Manual 32089, Rev. A, December 2000 3.1.2Analog Section Operation Single channel meters have one analog amplifier chain while the dual channel meters have two. The input from the power sensor is a differential DC level (with modulation for all but 30

32、0 series sensors). The 300 and 400 series sensors output the diode voltages directly. The 350, 600, and 700 series sensors have internal amplifiers. This DC level is amplified by selectable gain amplifiers, controlled by the instrument processor and associated logic elements. In CW mode, for signal

33、levels less than 38 dBm, the balanced detector voltages from the sensor are switched (chopped) between the inverting and non-inverting paths of the amplifier chain with CMOS solid-state switches. This chopping is done in the sensors when using the 600 and 700 series sensors and in the meter itself w

34、hen using the 300 and 400 series sensors. This essentially produces classic amplitude modulation at a low frequency rate thus converting the spectrum from around DC to around the chopping frequency. The purpose is to eliminate the DC input offset drift of the amplifiers and to reduce the 1/f noise.

35、The amplifiers are DC coupled in this power meter because above 38 dBm the chopper is not used and the DC must be amplified directly. In modulation mode (MAP and BAP), the high frequency AC component is separately amplified and remixed with the DC/low frequency amplifier output so that wide bandwidt

36、h can be achieved without compromising DC performance. This is done both at the first gain block of the 8650 and in the 600 and 700 series sensors. Both the amplitude modulated signal and the directly amplified DC go directly to the A-D converter. In the chopping mode (below 38 dBm input), the demod

37、ulation is done using digital signal processing. When the meter is zeroed, the instrument processor adjusts a D-A converter to sum a correction voltage into the amplifier chain. The use of this correction voltage prevents saturation of the amplifiers at high gain settings due to detector and amplifi

38、er offsets. A bias is also added to the A-D to achieve 13 bits of resolution out of a 12-bit A-D. The instrument power supply circuitry and the rear panel analog outputs are also located on the host board. The power supply is a linear/switching type supplying +3.3, +5, +6.5, 6.5, +12 and 12 volts. 3

39、.1.3Digital Section Operation Control for all instrument functions is provided by a combination of processing and programmable logic elements. The Motorola 68340 microprocessor acts as the primary control element. It accepts user interface and remote control information to set up the measurement pro

40、cesses and display/output the results. The output of each amplifier chain is a high speed Analog to Digital converter. This device is read by the system FPGA and thus sends its data to a Texas Instruments Floating Point Digital Signal Processor. These two devices provide the majority of the data acq

41、uisition and computation for the various measurement modes of the meter. Theory of Operation Manual 32089, Rev. A, December 20003-3 3.1.4Calibrator Operation The calibrator consists of two oscillators (one for the 50 MHz only version), an ovenized dual bridge leveling circuit, and a switched attenua

42、tor. The operation of the calibrator and the calibration process is covered by US patent 4,794,325 and various foreign patents. Initially the oscillators are turned off. The amplifiers are not powered up. All the pads are switched in. The oven temperature has reached 55 C. The D-A converter voltage

43、is zero. The DC current heats the thermistors until they reach about 125 C. When the thermistors are exactly 100 0.1 %, the bridge is in balance. There is no error voltage to the integrators U10D, U10A. The integrator will hold the voltage and current to the thermistor constant. The power to the the

44、rmistor is constant. The temperature in the oven is constant. The heat transfer out the thermistor leads is constant. The voltage at the output of U10D is measured. The switches are flipped. The microprocessor adjusts the DAC voltage until the comparator (U20) flips when the LSB is toggled. In effec

45、t the integrator (U11) slams from one rail to the other. This forms a very accurate 16-bit voltmeter. The microprocessor calculates the power dissipated in the bridge resistors. The power in the RF Thermistor is one third of this. This is stored as P1. The power dissipated in the RF thermistor stays

46、 CONSTANT. Any RF power that is dissipated by the thermistor adds to the DC power in the thermistor. The bridge integrator U10D will decrease the DC power to remain in balance. The voltage of U10D is measured with respect to U10A with the switches in their original positions. Again, the microprocess

47、or adjusts the D-A until the comparator flips for a LSB change. U10A simply provides a reference for variations in the oven temperature. Figure 3-2: Calibrator Block Diagram 25 dB6.25 dB12.5 dB DAC Instrument CPU EEPROM RF Thermistor DC Thermistor 1 GHz 50 MHz U10D U10A U20 U11 Series 8650A Universal Power Meters 3-4Manual 32089, Rev. A, December 2000 3.1.5Setting the Calibrator Level To set the calibrator power, an HP432 power meter with an HP8478B thermistor is placed at the calibrator output. The 432 output is monitored with a DVM connected to a computer syst