MODEL 1806A Dual Type IV Power Meter Instruction and
Contents
1. Dual Type IV Power Meter Model 1806A BRIDGE BRIDGE BIAS BIAS TEMP VOLTMETER TEMP VOLTMETER O READY VOLTAGE READY VOLTAGE ERROR ERROR Vcomp Optional Power Meter O Cable P N 138 652 Figure 1 3 Typical Setup for Measuring the 1 mW 50 MHz Reference Output of an RF Power Meter 1 6 Model 1806A Dual Type IV Power Meter Instruction and Service Manual Preparation for Use INSTRUMENT DESCRIPTION PREPARATION FOR USE OPERATING INSTRUCTIONS THEORY OF OPERATION MAINTENANCE SERVICE INFORMATION Model 1806A Dual Type IV Power Meter Instruction and Service Manual 2 1 TEGAM Preparation for Use Unpacking amp Inspection Each 1806A 15 put through a series of electrical and mechanical inspections before shipment to the customer Upon receipt of your instrument unpack all of the items from the shipping carton and inspect for any damage that may have occurred during transit Report any damaged items to the shipping agent Retain and use the original packing material for reshipment if necessary Upon Receipt inspect the carton for the following items Model 1806A Dual Type IV Power Meter Model 1806A Operating and Service Manual CD P N SYSIIB 840 01 Calibration Certificate Heater Cable X2 P N CA 10 48 Heater Cable X22. 2 5 111 OPERATING INSTRUCTIONS n nca win n ncn 3 1 1806A Front Panel Description 3 2 Figure 3 1 Model 18064 Front 3 2 1806A Rear Panel Description sess memes 3 3 Figure 3 2 Model 1806A Rear 3 3 RF Power Level 3 4 Connecting the Model 1806 3 4 Figure 3 3 Connections for a TEGAM or Weinschel Temperature Controlled Thermistor Mount 3 4 Model 1806A Dual Type IV Power Meter Instruction and Service Manual C Table of Contents Figure 3 4 Connections for an Agilent HP Temperature Compensated TNEM tOr MOUNT C 3 5 RF Power MCASUPEMICNIE view opus asas ife sis sta aedis 3 5 RF Power Level Measurement with an Agilent HP Thermistor Sensor 3 6 RF Power Level Measurement using the RVG 3 6 IV Theory ERN EEMN SERERE M Nnr E EE E RENE 4 1 Principle of DC Substitution rp REX EE E n E ea 4 2 Precision Pow
3. 5 6 Figure 5 4 Location of OUT T C and OUT 51 PS2 and PS3 5 6 Figure 5 5 Location of OUT T C and OUT on PS5 and 596 5 7 Heater Circuit Functionality 5 8 Figure 5 6 Connection of the 1N914 Diode to the 1806 5 8 Bridge NOLE ee re ter 5 9 Figure 5 7 Location of Bridge Board Jumper 5 9 Bridge Board Circuitry Test and Calibration 5 9 Calibration of Internal Resistance 5 10 Figure 5 8 Connection of the 100 Ohm Resistance Standard to the 1806A 5 10 Figure 5 9 Connection of a Temperature Controlled Thermistor Mount OO Gi e M 5 11 Bridge Balance mese essa anna nn 5 11 RVG Reference Voltage Generator Test 5 12 VI SERVICE INFORMATION ai SEP eerie 6 1 liac na a 6 2 Warranty Limitations ccc cece cece cece cece ee ee ence eee ehem nnns 6 2 Statement or CallDFSLbIOF esas iced CHEER PCR ee OP ek ARR e 6 2 Contact THROFROIOEIODI de at EE
4. 2 AM FLOAT Air Vent AC INPUT POWER AC input FLOAT GROUND Exhaust Fan with Filter connector power FUSE switch Figure 3 2 Model 1806A Rear Panel Air Vent with Filter The Air Vent allows air to flow into the Model 1806A to keep the internal components from overheating The filter keeps debris from entering the instrument Ensure there 15 at least two inches of space behind the instrument for proper airflow Inspect the filter daily for excessive dirt and dust wipe it clean with a lint free cloth as necessary AC INPUT POWER connector The AC INPUT POWER connector is a three prong connector mates with AC power cord supplied with unit AC input power FUSE The AC input power FUSE protects instrument from an over current condition A 1 6 Amp fuse Is used with the standard 110 Vac power supply a 0 8 Amp 15 used with the optional 220 Vac power Supply FLOAT GROUND Switch The FLOAT GROUND Switch is a two position toggle switch located on the rear panel This switch connects and disconnects the bridge board ground to chassis ground the up position connects the bridge board to ground and the down position disconnects the bridge board from ground floats Normal operation is with the switch in the GROUND up position If the LO input of the external DVM is grounded then the switch should be in the FLOAT down position Exhaust Fan The Exhaust Fan causes air to flow out of the Model 1806A to k
5. OUT N PS1 gt Te 57 XN e sd C O PS2 A2 A3 Bridge Circuit A1 Heater PS6 PCBs Circuit PCB PS3 55 Figure 5 1 Top view layout of Model 1806A subassemblies Model 1806A Dual Type IV Power Meter Instruction and Service Manual 5 3 IEGAM Maintenance Visual I nspection Remove top cover of the Model 1806A to expose the internal assemblies 1 Remove four Philips head screws that secure the Air Vent Filter to rear panel Clean the filter with soap and water rinse thoroughly and allow it to dry before reinstalling 2 Remove four rear panel screws in rear panel using 9 64 Allen Wrench Four rear panel screws Model 1806A 95 125 VAC 50 400 Hz 190VA MAX Fuse 1 6A 250V SLOW lt Figure 5 2 Location of Four Rear Panel Screws 3 Tilt rear panel down 4 Slide top cover towards the rear of the unit _ Six Bridge Board Housing top cover screws Figure 5 3 1806A Rear Panel Tilted Down and Top Cover Removed Location of six Bridge Board Housing Top Panel Screws 5 4 Model 18
6. Heater Cable P N CBL F1125 48 DVM or DMM ex OC OQ Figure 5 9 Connection of a Temperature Controlled Thermistor Mount to the 1806A BRI DGE BALANCE TEST The bridge balance test checks the Model 1806A bridge balance at a 30 0 7 mW operating bias 1 Ensure the Bridge Board Jumper is set to the 200 ohms position JP5 refer to Figure 5 7 The bridge board may need to be lifted from the bridge board housing for easier access If so turn the power off before touching the bridge board 2 Turn the Model 1806A POWER Switch to the ON position and allow five minutes for stabilization Model 1806A Dual Type IV Power Meter Instruction and Service Manual 5 11 Maintenance 8 Ensure the temperature controlled thermistor mount heater connector is connected to the Model 1806A TEMP connector using the appropriate heater cable refer to the thermistor mount Operation Manual Once the heater is connected allow two hours for the mount to warm up The READY indicator should be illuminated Connect the thermistor mount positive bias terminal to the Model 1806A BIAS VOLTAGE Red binding post Connect the thermistor mount negative bias terminal to the Model 1806A BIAS VOLTAGE Black binding post Once the bias voltage terminals are connected allow half an hour for the mount to stabilize Connect the DVM positive lead to the Model 1806A VOLTMETER Red binding post an
7. a icula aca sae PE PCR HD 6 2 Preparation for Calibration or Repair Service 6 3 Expedite Repair amp Calibration Form 6 4 d Model 1806A Dual Type IV Power Meter Instruction and Service Manual Instrument Description INSTRUMENT DESCRIPTION PREPARATION FOR USE OPERATING INSTRUCTIONS THEORY OF OPERATION MAINTENANCE SERVICE INFORMATION Model 1806A Dual Type IV Power Meter Instruction and Service Manual 1 1 TEGAM Instrument Description Abbreviations and Acronyms The following list contains all abbreviations used throughout this manual Abbreviations and acronyms that are not listed conform to MIL STD 12D CW Continuous Wave SUT Sensor Under Test DVM Digital Voltmeter ESDS Electrostatic Discharge Sensitive NIST National Institute of Standards and Technology RF Radio Frequency DC Direct Current RVG Reference Voltage Generator VOLTMETER a H vios TAE uu o TEMF VOLT 4 n A d a i Figure 1 1 Model 1806A Description Of Equipment Functional Description The TEGAM Model 1806A in conjunction with an external thermistor mount and a digital voltmeter DVM forms a precision power measurement system that measures microwave power within the freq
8. o 15 V RFI N Figure 4 1 Simplified Schematic of the Model 1806A Bridge Circuit Self Balancing Bridge Circuits The Model 1806A contains a bridge circuit that performs DC substitution Figure 4 1 shows a simplified schematic of the bridge circuit in the Model 1806A The self balancing bridge circuit in a closed loop configuration consists of two legs a precision resistance leg 200 ohm and a leg containing a thermistor element The precision resistance leg maintains a constant effective resistance value of 200 ohms When the power sensor is temperature stabilized by the temperature control circuit thermistor resistance varies solely due to the application of RF and DC power 4 2 Model 1806A Dual Type IV Power Meter Instruction and Service Manual TEGAM Theory of Operation Each leg uses an operational amplifier U1 or U2 to sense voltage imbalances and to drive transistors Q1 and Q2 to correct them The power supply assembly provides isolated 15 volt biasing to each op amp Since the voltage differential at the input stage of op amp U2 is negligibly small it provides a virtual common reference to op amp U1 i e it acts as a virtual common ground since the voltage approaches zero with respect to either ground This forces the current through the thermistor to equal the current through the precision resistance leg The application of RF power to the thermistor element creates a decrease in the voltage drop
9. If so turn the power off before touching the bridge board Connect the DVM to the Bridge Board PCB A2 or A3 at TP2 and TP5 Note ensure that this measurement is not made between TP3 and TP5 Current flow at TP3 will introduce error in this adjustment Adjust potentiometer R23 for a OV 10uV reading on the DVM Connect the DVM to the Bridge Board PCB A2 or A3 at TP7 and TP9 and adjust potentiometer R24 for OV 10uV reading on the DVM Turn the Model 1806A POWER Switch to the OFF position Disconnect the 1N914 diode from the Red and Black Binding Posts Calibration of Internal Resistance The internal resistance calibration procedure involves the alignment of several key resistors within the unit When performing this procedure ensure that the power is off while making connections 1 2 5 10 Ensure the Model 1806 Front Panel Switch is in the OFF position Remove Q7 from the Bridge Board PCB A2 or A3 Use jumpers to connect 1 on the Bridge Board PCB A2 or A3 to the junction of R21 and Q6 pin 1 Ensure the Model 1806A Bridge Board J umper 100 Ohms position P6 refer to Figure 5 7 The bridge board may need to be lifted from the bridge board housing for easier access If so turn the power off before touching the bridge board 100 Ohm Standard Figure 5 8 Connection of the 100 Ohm resistance standard to the 1806A Plug the 100 ohm resistance standard directly into the Model 1806A BIAS VOLTAGE Red and Bla
10. P N CA 11 48 Mount Bias Cable X2 P N 138 526 Power Cord P N As Required Mounting The Model 18064 is shipped with four feet mounted to the bottom cover When the Model 1806A is placed on a bench or table these feet support the instrument The Model 1806A can also be rack mounted in a standard 19 rack using the optional rack adapter kit RM 1825 A Safety I nformation amp Precautions The following safety information applies to both operation and service personnel Safety precautions and warnings may be found throughout this instruction manual and the equipment These warnings may be in the form of a symbol or a written statement Below is a summary of these precautions Terms in This Manual CAUTION statements identify conditions or practices that could result in damage to the equipment or other property WARNING statements identify conditions or practices that could result in personal injury or loss of life Terms as Marked on Equipment CAUTION indicates a personal injury hazard not immediately accessible as one reads the marking or a hazard to property including the equipment itself DANGER indicates a personal injury hazard immediately accessible as one reads the marking 2 2 Model 1806A Dual Type IV Power Meter Instruction and Service Manual IEGAM Preparation for Use Symbols As Marked in This Manual This symbol denotes where precautionary information may be found As Marked on Equipment
11. Power Linearity 1 to 10 mW 0 at imW Calibration Factor Drift Digital voltmeter Ga specifications specifications 4 6 Model 1806A Dual Type IV Power Meter Instruction and Service Manual Maintenance INSTRUMENT DESCRIPTION PREPARATION FOR USE OPERATING INSTRUCTIONS THEORY OF OPERATION MAINTENANCE SERVICE INFORMATION Model 1806A Dual Type IV Power Meter Instruction and Service Manual 5 1 Maintenance Table 5 1 List of Equipment Required for Calibration Voltmeter DC null detector Range 30 V Sensitivity of smallest scale 10 uV Input Impedance 100 kOhm or greater resistive Accuracy 2 of full scale Bandwidth 10 MHz Resolution 0 1 Ohms TEGAM Model SR1 100 resistance standard or equivalent Nominal Value 100 Ohms Accuracy 0 01 Connectors Banana plugs spaced 0 75 apart TEGAM or Weinschel temperature controlled RF Power Standard Nominal Resistance 200 Ohms Bias Voltage 2 42 2 48 VDC 1N914 silicon diode or equivalent 9 64 Allen Wrench Philips screwdriver REN Note If any test in this chapter fails contact TEGAM for assistance Contact information and instructions for returning an instrument to TEGAM can be found in Chapter VI Service Information in this manual 5 2 Model 1806A Dual Type IV Power Meter Instruction and Service Manual Maintenance
12. This current drives the bridge to restore balance As the bridge nears the steady state condition Q3 causes the READY LED to illuminate If the mount is cold the READY LED does not illuminate since the Darlington pair configuration made up by Q1 and Q4 is not in a conducting state U1 U2 responds to an imbalance signal from an overheated mount by turning off Q3 so that it passes no current to the heater or READY LED Transistor Q2 and Resistor R16 combine to provide circuit protection by limiting current in the event of an output short circuit Calculating Uncertainty Measurement uncertainty when using the Model 1806A can be calculated with the following formula Up V I T Mes Where Up uncertainty of the power measurement of the Model 1806A Uc uncertainty of the cal factor for the thermistor sensor which is frequency dependent Ig the random part of the uncertainty of the instrumentation Mer mismatch error which is frequency dependent Mismatch Uncertainty Mer Device mismatch is the term used to describe the differences in impedance between RF devices This difference in impedance causes some of the RF power to be reflected back from one device to another thus not all applied RF power is transferred from one device to another The amount of power that is not transferred can be characterized as the reflection coefficient or The reflection coefficient for the thermistor mount is usually included as part of the c
13. You can contact TEGAM customer service via the TEGAM website www tegam com or by calling 440 466 6100 OR 800 666 1010 The RMA number is unique to your instrument and will help us identify your instrument and to address the particular service request by you which is assigned to that RMA number Of even more importance Is a detailed written description of the problem which should be attached to the instrument Many times repair turnaround is unnecessarily delayed due to a lack of repair instructions or lack of a detailed description of the problem The detailed problem description should include information such as measurement range trigger mode type of components being tested is the problem intermittent when is the problem most frequent has anything changed since the last time the instrument was used etc Any detailed information provided to our technicians will assist them in identifying and correcting the problem in the quickest possible manner Use the Expedite Repair amp Calibration form provided on the next page to provide detailed symptoms of the instrument s problem Once this information is prepared and sent with the instrument and RMA number to our service department we will do our part in making sure that you receive the best possible customer service and turnaround time possible Model 1806A Dual Type IV Power Meter Instruction and Service Manual 6 3 Service Information Expedite Repair amp Calibration Form Use
14. across the thermistor element due to its negative temperature coefficient This decreased voltage drop in turn creates an unbalanced bridge condition When resistance in the thermistor element leg of the bridge changes due to the application of RF power op amp U1 senses a voltage difference between V4 and V4 and causes to equal Va When V equals V the voltage across the thermistor element leg equals the voltage across the precision resistance leg Also the closed loop circuit configuration maintains equal current throughout the bridge Since the voltage and current throughout the circuit is equal the resistance in both halves is also equal Therefore when the thermistor mount s temperature is stabilized and RF power is applied a change in voltage across the precision resistance leg is proportional to the amount of RF power applied to the thermistor element Power Measurements The precision measurement system measures RF power in terms of a power change across the precision resistance leg A digital voltmeter measures voltage across the precision resistance leg which can be used to determine the power by the following equation 200 Where P power across the precision resistance leg V voltage measured across the precision resistance leg 200 resistance value of precision resistance leg The RF power introduced to the thermistor is directly proportional to the change in DC power across the precision resistor The
15. illuminated once again Oscilloscope OQ CH1 CH2 TRIG E Dual Type IV Power Meter Model 1806A BRIDGE B BIAS TEMP VOLTMETER N VOLTAGE ON O READY O READY o error Q ERROR pu 1N914 Figure 5 6 Connection of the 1N914 Diode to the 1806A Model 1806A Dual Type IV Power Meter Instruction and Service Manual Maintenance Bridge Noise Test The Bridge Noise Test employs an oscilloscope to measure noise the Type IV bridge circuit The Bridge Noise test ensures that the Model 1806A bridge circuit s does not source noise that would disrupt measurements or bridge balance capability 1 Turn the Model 1806A POWER Switch to the OFF position 2 Connect the anode of the 1N914 diode to the Model 1806A BIAS VOLTAGE Red Binding Post Refer to Figure 5 6 3 Connect the cathode of the 1N914 diode to the to the Model 1806A BIAS VOLTAGE Black Binding Post 4 Connect the oscilloscope s positive and negative terminals to the Model 1806A VOLTMETER Red and Black Binding Post respectively Figure 5 7 Location of Bridge Board Jumper 5 Move the Model 1806A Bridge Board Jumper to the 100 ohms position JP6 refer to Figure 5 7 The bridge board may need to be lifted from the
16. power level using the following steps Model 1806A Dual Type IV Power Meter Instruction and Service Manual 3 5 TEGAM Operating Instructions First calculate the level of proportional DC substituted power from the operating resistance and DVM readings with the equation Vi V2 200 Where Pac DC substituted power which is proportional to the applied RF power V DVM reading across the bridge in the absence of RF power V5 DVM reading across the bridge with RF power applied 200 nominal resistance of the 1806A Type IV bridge in Ohms Next calculate the applied RF power level using the applicable calibration factor for the thermistor sensor and the level of DC substituted power Prr Pac K Where Par Level of applied RF power DC substituted power which is proportional to the applied RF power K calibration factor of thermistor sensor RF Power Level Measurement with an Agilent HP thermistor sensor Agilent HP temperature compensated thermistor mounts have one set of thermistor beads for detecting RF power and one set for compensating for ambient temperature changes It is not necessary to use the compensating set of thermistor beads to measure RF power If the compensation beads are not used then the procedure for measuring power 15 the same as described in the previous section Voltage measurements with no RF power V4 will have to be taken for each RF power measurement That is becau
17. this form to provide additional repair information and service instructions The completion of this form and including it with your instrument will expedite the processing and repair process Number Additional Contact I nfo Repair nstructions Evaluation C Calibration Only 0 Repair Only L Repair amp Calibration LJ A2LA Accredited Calibration Extra Charge Detailed Symptoms Include information such as measurement range instrument settings type of components being tested is the problem intermittent When 15 the problem most frequent Has anything changed with the application since the last time the instrument was used etc 6 4 Model 1806A Dual Type IV Power Meter Instruction and Service Manual
18. to Figure 5 4 The voltage should be 15 VDC 0 15V Move the positive lead of the DVM to PS1 OUT refer to Figure 5 4 the voltage should be 15 VDC 0 15V Repeat Steps 6 through 7 for PS2 PS5 and PS6 refer to Figure 5 5 for location of OUT T C and OUT for PS5 and PS6 Using an Oscilloscope measure AC voltage between PS3 OUT and OUT Ensure that the scope probe is connected to OUT and the ground lead of the scope probe 15 connected to OUT refer to Figure 5 4 The ripple voltage should be less than 3 mVpp Using an Oscilloscope measure AC voltage between PS7 OUT and T C Ensure that the scope probe is connected to OUT and the ground lead of the scope probe 15 connected to T C refer to Figure 5 1 The ripple voltage should be less than 3 mVpp Using an Oscilloscope measure AC voltage between PS1 OUT and T C Ensure that the scope probe is connected to OUT and the ground lead of the scope probe is connected to T C refer to Figure 5 4 The ripple voltage should be less than 3 mVpp Move the oscilloscope probe to PS1 OUT refer to Figure 5 4 the ripple voltage should be less than 3 mVpp Repeat Steps 11 and 12 for PS2 PS5 and PS6 refer to Figure 5 5 for location of OUT T C and OUT for PS5 and PS6 Note The Model 1806A is a Dual Type IV Power Meter meaning it has two Bridge Circuits Heater Control Circuits and RVGs The following procedures should be performed twic
19. 06A Dual Type IV Power Meter Instruction and Service Manual Maintenance 6 A Loosen the six screws that secure the Bridge Board Housing top cover to remove it Conduct a visual inspection of the Model 1806A including the Power Supplies Temperature Control Board Bridge Circuit Board and Interconnections Look for any obvious signs of damage Leave the top cover off to perform the rest of the Function Tests and Calibration procedures Replace the cover and the rear panel when service on the Model 1806A is finished Warning Many of the procedures described are performed with power applied to the instrument while the protective covers are removed The electrical energy present at some points may cause personal injury if directly contacted These procedures should be performed by qualified personnel and caution should be used Power Up Operational Test The power up operational test ensures that the Model 1806A power supplies and error indicator are working properly 1 2 3 4 5 6 Ensure the Model 1806A Front Panel Switch is in the OFF position Verify that fuse FS1 is installed and is the correct value refer to Chapter I Preparation for Use Ensure the Model 1806A rear panel FLOAT GROUND Switch to the FLOAT position Turn the Model 1806A POWER Switch to the ON position Ensure the POWER ON indicator and ERROR LED illuminate Turn the Model 1806A POWER Switch to the OFF position Float G
20. 14 counter clockwise The cap and fuse will spring out replace the fuse Align the tab on the fuse cap with the notch on the fuse housing push the cap and fuse into the housing and rotate the cap clockwise with a flat screwdriver to lock the cap down Model 1806A Dual Type IV Power Meter Instruction and Service Manual 2 5 Operating Instructions INSTRUMENT DESCRIPTION PREPARATION FOR USE OPERATING INSTRUCTIONS THEORY OF OPERATION MAINTENANCE SERVICE INFORMATION Model 1806A Dual Type IV Power Meter Instruction and Service Manual 3 1 TEGAM Operating Instructions Model 1806A Front Panel Description Dual Type IV Power Meter Model 1806A BRIDGE A BRIDGE B BIAS VOLTAGE TEMP VOLTMETER BIAS VOLTAGE TEMP VOLTMETER Xen OO POWER ON ERROR RVG Bias VOLTAGE TEMP VOLTMETER Indicator Indicator Switch Connectors Connector Connectors POWER READY Switch Indicator Figure 3 1 Model 1806A Front Panel POWER Switch The POWER switch switches the power input to the instrument on and off This switch has a built in indicator that is illuminated when power is on See POWER ON indicator POWER ON Indicator The POWER ON indicator illuminates when instrument power is on It is built into the POWER Switch READY Indicator The READY indicator is a green LED that illuminates when the RF power standard has reached its internal operating temperature of approximately 60 C Allow two hours for the power standard to reach this temperatu
21. Agilent HP temperature compensated thermistor mount The Agilent HP has one set of thermistor beads for detecting RF power and one set for compensating for ambient temperature changes It 15 not necessary to use the compensating set of thermistor beads to measure RF power but if they are used both Bridge A and Bridge B and two DVMs are required The BIAS VOLTAGE on the 1806A 15 connected to the Agilent HP by using TEGAM cable P N 138 652 The red spade lug connectors on the cable are connected to the red BIAS VOLTAGE binding posts on the 1806A and the black spade lugs are connected to the black binding posts The VOLTMETER red and black connectors are connected to the DVM DC voltage positive and negative input connectors respectively The VOLTMETER connectors are binding posts banana jacks so banana plugs or spade lugs will mate with them RF Power Measurement The Model 1806A does not measure the RF power level directly Instead DVM measures DC voltages before and after the application of RF power to the thermistor mount This necessitates calculation of the RF power level using data obtained from the DVM measurements To calculate the RF power level applied to the thermistor sensor measure the voltage at the 1806A VOLTMETER terminals with the DVM before the application of RF power and record it as V4 Then measure the voltage across the bridge after applying RF power to the thermistor sensor and record that measurement as V Determine the RF
22. CAUTI ON DO NOT APPLY POWER TO THE INSTRUMENT BEFORE READING THIS SECTION The standard power supply in a Model 1806A operates with a line voltage of 95 to 125 Vac at 50 to 400 Hz A 210 to 250 Vac power supply can be ordered as a factory installed option Each power supply requires a different fuse It is strongly recommended that the line voltage frequency and fuse type be verified for the type of power supply in the unit before powering it Check the Power Cord Make sure the power cord supplied with the Model 18064 is not frayed broken or cracked A damaged power cord is a fire and electrical hazard If the power cord is damaged it should be replaced P N 068 21 Use the Proper Fuse To avoid fire hazard use only the correct fuse type as specified for the AC power supply in the unit For the standard 95 125 Vac power supply use a 1 6 Amp Slo Blo fuse TEGAM P N FU 1804 3 For the optional 210 250 Vac power supply use a 0 8 Amp Slo Blo fuse TEGAM P N 430008 AC INPUT PETER SEGROUNI Figure 2 2 Location of Figure 2 2 Location of the FUSE __ FUSE The fuse 15 located between the AC INPUT POWER connector and the FLOAT GROUND switch on the rear panel as depicted in Figure 2 2 Before replacing the fuse place the Model 1806A Front Panel Switch to the OFF position and remove power cord on the back of the Model 1806A To replace the fuse remove the fuse cap by inserting a flat screwdriver into the slot of the cap and rotate about
23. E A 2 2 Weide 2 2 Safety Information amp Precautions sss 2 2 Terme CAS Mandal 2 2 Terms aS Marked on nns 2 2 cines KT T 2 3 Grounding the EQUIPMENL c cece cece ee eeee seen enne 2 3 Danger Arising from the Loss of Ground eee 2 3 Use in Proper Environment ssssssssssssse Ies 2 3 Do Not Use in Explosive 2 4 Do Not Block Air Vents on Rear 2 4 Ensure Power Switch is Accessible n 2 4 Do Not Operate without Covers essem s 2 4 Figure 2 1 Model 1806A AC INPUT POWER and FUSE Location 2 4 Servicing Safety Summary een 2 4 DO MOE Service AIONE an dade E ERR RH VUA Meca OE 2 4 Use Care when Servicing with Power On or 2 4 2 5 LING Voltage Eaa da hdd Rd ance d qat aae a Ra 2 5 CHECK CO re RETI TIU 2 5 WS tne Proper PUSSY 2 5 Figure 2 2 Location of the
24. MODEL 1806A Dual Type I V Power Meter Instruction and Service Manual PN 1806A 901 01 Publication Date June 2010 REV H TEGAM INC MODEL 1806A DUAL TYPE IV POWER METER Instruction and Service Manual PN 1806A 901 01 Publication Date J une 2010 REV H NOTE This user s manual was as current as possible when this product was manufactured However products are constantly being updated and improved Because of this some differences may occur between the description in this manual and the product received TEGAM is a manufacturer of electronic test and measurement equipment for metrology calibration and production test We also provide repair calibration and other support services for a wide variety of test and measurement equipment including RF power sensor calibration systems RF attenuation measurement systems resistance standards ratio transformers arbitrary waveform generators micro ohmmeters LCR meters handheld temperature calibrators thermometers humidity and temperature control devices and more TEGAM also repairs and calibrates test and measurement equipment formerly manufactured by Electro Scientific Industries ESI Gertsch Keithley Instruments Lucas Weinschel and Pragmatic Instruments A complete list can be viewed on our Product Service Directory at www tegam com For more information about TEGAM and our products please visit our website at www tegam com or contact one of our customer servic
25. R Connectors are spade lug connecting posts banana jacks These connectors complete the DC path between the Model 1806A and a digital voltmeter with at least 61 2 digit resolution DC voltage present across the VOLTMETER connectors is equivalent to the voltage across the thermistor element The red connector is for positive DC voltage and the black connector is for negative DC voltage Model 1806A Rear Panel Description voe AC INPUT POWER FUSEGROUND 4 b
26. RATION MAINTENANCE SERVICE INFORMATION Model 1806A Dual Type IV Power Meter Instruction and Service Manual 4 1 TEGAM Theory of Operation Principle Of DC Substitution The Model 1806A uses the principle of DC substitution to measure RF power DC substitution refers to the measurement of RF power according to the amount of DC power that must be substituted for the RF power in a bolometer in order to cause equivalent thermal effects This is done by monitoring voltage changes of the 1806A s Type IV DC self balancing bridge circuits Precision Power Measurement The Model 1806A RF Power Meter and a 200 Ohm thermistor power sensor with a 6 2 digit resolution digital voltmeter combine to provide a precision power measurement system This system features the Model 1806A closed loop self balancing Type IV Bridge circuit consisting of two legs a precision 200 ohm resistance leg and a leg linked to an external thermistor element A thermistor is a type of bolometer whose resistance decreases as a function of increasing heat associated with ambient temperature or applied power This system also features the Model 1806A temperature control circuitry that temperature stabilizes TEGAM and Weinschel thermistor mounts This eliminates changes in the thermistor element s resistance due to ambient temperature changes and thus isolates the causes of thermistor variation to the application of RF and DC power only VOLTMETER RED BLACK O 200 Q
27. S Frame or Chassis Terminal Earth Ground Terminal v Alternating Current Grounding the Equipment This product is grounded through the grounding conductor of the power cord WARNING To avoid electrical shock or other potential safety hazards plug the power cord into a properly wired receptacle before using this instrument The proper grounding of this instrument is essential for safety and optimizing instrument operation Danger Arising from Loss of Ground WARNING If the connection to ground is lost or compromised a floating potential could develop in the instrument Under these conditions all accessible parts including insulating parts such as keypads and buttons could develop a hazardous voltage and put the user at risk AN Use in Proper Environment Normal calibration laboratory practice dictates that the environment should be closely controlled This will minimize errors introduced by temperature and humidity changes A nominal temperature of 23 C 73 4 F provides a good working condition A tolerance of 1 C gives allowable temperature spread Controlled temperatures also stabilize the aging process of the standards CAUTION The Model 1806A has a specified ambient temperature range of 12 to 32 C 4 54 to 90 F Operating beyond these limits can affect the accuracy of the instruments and damage internal circuitry Model 1806A Dual Type IV Power Meter Instruction and Service Manual 2 3 TEGAM Preparation
28. alibration data Mismatch error Mer is determined from the reflection coefficients of both the power sensor and the power source as follows Mer 1 1 1 Pi x Ir Where Mer residual mismatch error reflection coefficient for the power sensor I reflection coefficient for the power source Reflection Coefficient is a complex number expressed as a vector quantity A vector quantity has two components a magnitude and phase angle The magnitude of the reflection coefficient is symbolized by the Greek letter rho and the phase angle by the Greek letter phi Often the magnitude is the only part of the reflection coefficient used which will yield a worse case mismatch uncertainty Sometimes the Standing Wave Ratio SWR of a device is given rather than the reflection coefficient SWR is a scalar quantity and related to follows Model 1806A Dual Type IV Power Meter Instruction and Service Manual 4 5 Theory of Operation Where magnitude of the reflection coefficient S Standing Wave Ratio SWR Instrumentation Uncertainty 1c These uncertainties are limited by the quoted accuracies of the various equipment involved Refer to Table 4 1 for an analysis Specified Accurac Effect on Uncertaint Model 1806A DC Substitution Bridge Accuracy 0 003 0 003 TEGAM or Weinschel Thermistor see manufacturer s specifications for others Connector Repeatability 80 30 1 Temperature drift 0 05
29. bridge board housing for easier access lf so turn the power off before touching the bridge board 6 Turn the Model 1806A POWER Switch S1 to the ON position 7 Ensure that the oscilloscope indicates less than 10mV peak to peak amplitude with no short term bursts or large peak transients Bridge Board Circuitry Test and Calibration The bridge board circuitry test checks the Model 1806A bridge board for amplifier offset and provides a calibration of bridge board components This test uses a Digital Voltmeter DVM as a null meter The DVM should be isolated from ground or battery operated After testing begins the red front panel ERROR Indicator should remain dark throughout the entire procedure except for momentary flashes when changing the bridge operating resistance setting If the ERROR Indicator remains lit there is a malfunction that should be corrected before calibration can proceed Contact TEGAM for assistance Contact information and instructions for returning an instrument to TEGAM can be found in Chapter VI Service Information in this manual Model 1806A Dual Type IV Power Meter Instruction and Service Manual 5 9 Maintenance Ensure the 1N914 diode is connected across the Model 1806A BIAS VOLTAGE Red and Black Binding Post Also the Model 1806A Bridge Board Jumper should be in the 100 Ohms position J P6 refer to Figure 5 7 The bridge board may need to be lifted from the bridge board housing for easier access
30. cator illuminates Connect the positive lead of a Digital Voltmeter DVM to J3 Pin 1 on the Heater Circuit PCB A1 Connect the negative lead of the DVM to J3 Pin 2 on the Heater Circuit PCB Al The voltage should be 20 VDC 0 6 V Connect an oscilloscope probe to J3 Pin 1 on the Heater Circuit PCB A1 and the ground lead of the scope to the J3 Pin 2 Set the scope to measure the AC voltage The ripple voltage should be less than 1 mVpp c PN BOG TEMPERATURE Rey i K Uh eyo q ns ls EP EZ f Figure 5 4 Location of OUT and OUT on 51 PS2 and 53 4 Using DC Digital Voltmeter measure between PS3 OUT and OUT Ensure that the positive lead of the DVM is connected to OUT and the negative lead of the DVM is connected to OUT refer to Figure 5 4 The voltage should be 5 VDC 0 1 V Using a DC Digital Voltmeter measure between PS7 OUT and T C Ensure that the positive lead of the DVM is connected to OUT and the negative lead of the DVM is connected to T C refer to Figure 5 1 The voltage should be 15 VDC 0 15 V Model 1806A Dual Type IV Power Meter Instruction and Service Manual Maintenance 6 10 11 12 13 Using a DC Digital Voltmeter measure between 51 OUT and T C Ensure that the positive lead of the DVM is connected to OUT and the negative lead of the DVM is connected to T C refer
31. change in DC power across the precision resistor leg is given by AP Where AP the change in power across the precision resistance leg when RF power is applied to the thermistor leg P power across the precision resistance leg without RF power applied P gt power across the precision resistance leg with RF power applied To determine the power across the precision resistance leg without RF power applied measure the voltage before the application of RF power V1 To determine the power across the precision resistance leg with RF power applied measure the voltage during the application of RF power V5 Once these two voltage measurements are made the power can be determined by using the first equation By substituting for and from the previous formula AP Vi Vo 200 200 Combining terms AP V1 200 Model 1806A Dual Type IV Power Meter Instruction and Service Manual 4 3 TEGAM Theory of Operation Where AP the change in power across the precision resistance leg when RF power is applied to the thermistor leg V DVM reading across the bridge in the absence of RF power V DVM reading across the bridge with RF power applied 200 nominal resistance of the thermistor in Ohms Since the change in power across the precision resistor is DC power AP is also represented as The change in DC power across the precision resistor is directly proportional to the RF power introd
32. ck Binding Posts Connect a DVM with microvolt sensitivity between the Bridge Board PCB A2 or A3 at TP2 and TP5 to act as a null detector Turn the Model 1806A POWER Switch to the ON position and allow five minutes for Stabilization Model 1806A Dual Type IV Power Meter Instruction and Service Manual Maintenance 7 Adjust potentiometer R32 for OV 10uV reading on the null detector 8 Turn the Model 1806A POWER Switch 51 to OFF position 9 Use a jumper to connect TP8 to the junction of R30 and R33 on the Bridge Circuit PCB 10 Remove Shorting Plug J P4 from the Bridge Circuit PCB Set the Model 1806A Bridge Board Jumper to the 200 ohms position JP5 refer to Figure 5 7 The bridge board may need to be lifted from the bridge board housing for easier access If so turn the power off before touching the bridge board 11 Turn the Model 1806A POWER Switch to the ON position and allow five minutes for stabilization 12 Adjust potentiometer R28 for OV 10uV reading on the null detector 13 Turn the Model 1806A POWER Switch S1 to the OFF position 14 Remove jumpers from between TP8 and the junction of R30 and R33 15 Remove jumpers from between 1 and the junction of R21 and Q6 Pin 1 16 Re insert Q7 and J P4 Dual Type IV Power Meter Model 1806A BRIDGE A BRIDGE B BIAS VOLTAGE TEMP VOLTMETER ON VOLTMETER D Ep QD ERROR OO C
33. d the DVM negative lead to the Model 1806A VOLTMETER Black binding post The voltmeter should read 2 45 0 03 VDC Record the voltmeter reading for each bridge circuit A and B Calculate the actual DC bias power for each bridge using the following equation P v 200 Where P DC bias power V volt meter reading from Step 6 200 nominal resistance of the 1806A Type IV bridge in Ohms Verify the DC bias power for Bridge A equals Bridge B within 0 6 4uW RVG Reference Voltage Generator Test The RVG test checks the internal Reference Voltage Generator is functioning and in tolerance It also verifies the functionality of the RVG switch on the front panel 1 2 5 12 Use the same set up configuration used for the Bridge Balance Test refer to Figure 5 9 With the RVG switch in the OFF position measure the DC voltage across the Model 1806A VOLTMETER binding posts Record this voltage as the Bias voltage With the RVG switch in the TEST position measure the DC voltage across the Model 1806A VOLTMETER binding posts The voltmeter should read 2 500 0 001 VDC Record this voltage as the RVG voltage With the RVG switch in the ON position measure the DC voltage across the Model 1806A VOLTMETER binding posts This voltage should equal the RVG voltage minus the Bias voltage Reassemble the Model 1806A Take care when replacing the cover on the Bridge Board Housing that no wires will be pinched between the cove
34. e once for Bridge A and once for Bridge B Model 1806A Dual Type IV Power Meter Instruction and Service Manual 5 7 Maintenance Heater Circuit Functionality Test This procedure verifies the functionality of the thermistor mount heater control circuit and READY Indicator The temperature controlled thermistor standard internal heater should be disconnected from a heater controller at least 30 minutes This will allow the thermistor standard to cool down enough to test the READY indicator 1 5 8 Connect the temperature controlled thermistor mount heater connector to the Model 1806A TEMP connector using the appropriate heater cable refer to the thermistor mount operation manual Set the Model 1806A front panel POWER Switch to the ON position and ensure that the front panel POWER ON Indicator lights Immediately verify that the READY LED is OFF Confirm that READY LED Is illuminated within two hours Illumination of the READY LED indicates a near thermal balanced condition of the thermistor mount heater Approximately 2 hours are required to achieve mount temperature stability for a completely cold mount During the time it takes for the thermistor heater to stabilize the other procedures in this chapter may be performed After the READY LED is illuminated with power still applied remove the thermistor mount heater cable Verify that READY Indicator is extinguished Reconnect the heater cable verify the READY LED is
35. e representatives at sales tegam com or 800 666 1010 TEGAM Ten Tegam Way Geneva Ohio 44041 Telephone 440 466 6100 Fax 440 466 6110 E mail sales tegam com Model 1806A Dual Type IV Power Meter Instruction and Service Manual Table of Contents Instrument Description cs e CRN 1 1 Abbreviations and nnns 1 2 Figure 1 1 Model 1806A e enhn nnns 1 2 DoScripEIDDHor EUDEN serina amanda cadens lia 1 2 FUNCTION Gl Piceno D T T 1 2 Physical Henne ns 1 3 rib atte Rc 1 3 Table 1 1 Physical and Electrical Specifications 1 3 Additional 1 4 Table 1 2 Additional Equipment 1 4 PDO GAG ONG RTT TENER EET 1 4 Figure 1 2 Typical Setup for Calibrating a TEGAM or Weinschel Feedthrough Thermistor Mount sees 1 5 Figure 1 3 Typical Setup for Measuring the 1 mW 50 MHz Reference Output of an RF Power 1 6 11 PREPARATION FOR USE 2 1 UNPACKING GelNSPeCH ON Rr ua
36. eep the internal components from overheating Ensure there is at least two inches of space behind the instrument for proper airflow Model 1806A Dual Type IV Power Meter Instruction and Service Manual 3 3 TEGAM Operating Instructions RF Power Level Measurement The Model 1806A is one component in a precision measurement system that measures RF power in terms of a DC voltage change across the Model 1806A bridge circuit This system measures the voltage change with a digital voltmeter DVM with a 6 5 digit resolution or the same DVM and Reference Voltage Generator RVG when the applied RF power level is small less than a milliwatt This section describes both these two methods of measurement Connecting The Model 1806A Before any measurements are taken the Model 1806A must be connected to a thermistor mount and a voltmeter Dual Type IV Power Meter Model 1806A BRIDGE A BRIDGE B BIAS BIAS VOLTAGE TEMP VOLTMETER ON VOLTAGE TEMP VOLTMETER ON CG ua OO QO rer Heater Cable DVM or DMM ex OC OQ Figure 3 3 Connections for a TEGAM or Weinschel Temperature Controlled Thermistor Mount Figure 3 3 shows the connections for a TEGAM or Weinschel temperature controlled thermistor power standard One these standards can be connected to either Bridge A or Bridge B a standard can be connected
37. er nnns 4 2 Figure 4 1 Simplified Schematic of the Model 1806A Bridge Circuit 4 2 Self Balancing Bridge 4 2 Power Measurements 4 3 Figure 4 2 Simplified Schematic of the Model 1806A Heater Circuit 4 4 Controlling Thermistor 4 4 Calculating Uncertainty cnni aa kane Rao doe Ea ER E sand cues Ee thane es aca ca 4 5 Mismatch Uncertainty Mep Hmm 4 5 Instrumentation Uncertainty lg hme 4 6 Table 4 1 Typical Instrumentation Error Analysis lg 4 6 VI Maintenalic Gub vela vadwd AV VN MM MM 5 1 Table 5 1 List of Equipment Required for 5 2 Figure 5 1 Top View Layout of Model 1806A Subassemblies 5 3 VISUAL INSPEC TI TT T UT 5 4 Figure 5 2 Location of Four Rear Panel 5 4 Figure 5 3 1806A Rear Panel Tilted Down and Top Cover Removed 5 4 PowerUp Operational 2 1 C ace rol elc EO eK dede dca 5 5 Float Ground SWITCH T eS scuss ax uisa aoo ca tac CIR ERO I RC CR ca ct Nx i 5 5 POWO SUNY RESUS ais T
38. for Use CAUTION When the Model 1806A 15 to be stored for extended periods pack the instrument into a container Place container in a clean dry temperature controlled location If instrument is to be stored in excess of 90 days place desiccant with items before sealing container The safe environmental limits for storage are 40 to 75 C 40 to 167 F at less than 80 non condensing relative humidity Do Not Use in Explosive Environments CAUTION The 1806A is not designed for operation in explosive environments Do Not Block Air Vents on Rear Panel CAUTION The Model 1806A has an air intake and exhaust on the back panel of the instrument When installing the Model 1806A ensure there is at least two inches of space behind the instrument for airflow DO NOT set the instrument on its rear panel as its airflow will be restricted and may result in damage to the internal circuitry Ensure Power Switch is Accessible CAUTION Ensure that the POWER switch Is easily accessible at all times and nothing is in place that would impede proper use Do Not Operate Without Covers WARNING This device should be operated with all panels and covers in place Operation with missing panels or covers could result in personal injury AC INPUT POWER GROUND FUSE Figure 2 1 Model 1806A AC INPUT POWER and FUSE location FOR QUALI FIED SERVICE PERSONNEL ONLY AN Servicing Safety Summary Do Not Service Alone Do not perform service o
39. gh and terminating power sensors The ratio of the two power levels is the SUT s calibration factor 1 2 Model 1806A Dual Type IV Power Meter Instruction and Service Manual TEGAM Instrument Description Physical Description Refer to Table 1 1 for the physical and electrical specifications of the Model 1806A The Model 1806A front panel contains the INPUT POWER switch as well as two sets one for each Bridge of BIAS VOLTAGE TEMP and VOLTMETER connectors The Model 1806A front panel also has two RVG switches for each bridge which enables the internal Reference Voltage Generator Additionally there are READY and ERROR indicators on the front panel The rear panel contains the input power connector and fuse FLOAT GROUND switch and vents for airflow The Model 1806A is designed to sit on a bench but can be mounted in a 19 rack with rack mount kit RM 1825 sold separately call TEGAM for details Specifications Table 1 1 lists the physical and electrical specifications of the Model 1806A Table 1 1 Physical and Electrical Specifications Substitution Bridge Accuracy 0 003 Temperature Controller Bias Power Temperature Sensitivity 2 UW C per hour Ambient Temperature Dynamic Range 12 to 32 C 54 to 90 F Mount Warm Up Time 2 hours nominal Mount Internal Temperature Approximately 60 C 140 F Loop Gain 80 dB minimum Open Loop Frequency Response 0 1 Hz Warm Up Drive saturated 8 10 V 200 mA minimum I ndicator G
40. luminate the READY LED when the power standard has reached its operating temperature Refer to Figure 4 2 for the following discussions concerning the temperature control circuit 4 4 Model 1806A Dual Type IV Power Meter Instruction and Service Manual TEGAM Theory of Operation The Wheatstone Bridge composed of R1 R2 R3 and R4 is actually wire wound around a thermal mass and not only heats the mass but also detects the temperature of it The wiring heats the mass to a temperature above the ambient temperature The thermistor beads are mounted on this thermal mass and insulation surrounds the assembly to improve temperature stability Two windings represented as R1 and R2 of zero temperature coefficient wire manganin make up two legs of the bridge The remaining two bridge windings R3 and R4 have a positive temperature coefficient wire nickel When the operating temperature is reached the heater windings provide equal resistance and the bridge balances The temperature is determined such that the thermistor bead bias power is 30mW 0 7 mW U1 a high gain amplifier with excellent offset drift characteristics senses imbalances across the bridge U1 U2 interaction provides a varying response to thermal bridge imbalances according to the relationship between the voltage differential inputs U1 U2 amplifies an imbalance signal from a cold bridge that forces the series pass transistor Q3 to pass a current proportional to the imbalance signal
41. nce Voltage Generator function minimizes voltmeter uncertainties by enabling use of a measurement scale that has better resolution When the RVG is used calculation of the RF power level requires a different process First place the RVG switch in the ON position With no RF power applied to the thermistor mount take a voltage reading from the VOLTMETER terminals using the DVM and record this value as Vp Then apply RF power to the thermistor mount and record this value as Vp Use these values and the following method to calculate the applied level of RF power 3 6 Model 1806A Dual Type IV Power Meter Instruction and Service Manual TEGAM Operating Instructions Pac 2 2 5 Vp V3 Vo Vp 200 Where Pac DC substituted power which is proportional to the applied RF power 2 5 value of the RVG in volts Vp DVM reading across the bridge in the absence of RF power Vp DVM reading across the bridge with RF power applied 200 nominal resistance of the 1806A Type IV bridge in Ohms Apply the thermistor mount calibration factor to find the level of RF power Par Pac K2 Where Pkr Level of applied RF power DC substituted power which is proportional to the applied RF power K calibration factor of the thermistor sensor Model 1806A Dual Type IV Power Meter Instruction and Service Manual 3 7 Theory of Operation INSTRUMENT DESCRIPTION PREPARATION FOR USE OPERATING INSTRUCTIONS THEORY OF OPE
42. odels manufactured by Agilent HP with cable P N 138 652 Digital Volt Meter DVM DC Volts 10 V range 6 digit minimum Lower resolution and range can be used with the RVG feature APPLI CATI ONS The TEGAM Model 1806A Dual Type IV Power Meter is designed for measuring RF power While this instrument is not designed for remote programming the process of measuring RF power can be automated if the additional equipment used can be remotely programmed Figures 1 2 and 1 3 show some typical applications for the 1806A The 1806A and a 200 Ohm thermistor mount can be used for any application where average RF power level measurements need to be precisely made 1 4 Model 1806A Dual Type IV Power Meter Instruction and Service Manual Instrument Description DVM or DMM DVM or DMM V 3 E O O OIO BRIDGE A BIAS BRIDGE B BIAS READY VOLTAGE READY VOLTAGE ERROR ERROR TEMP VQLTMETER Model F11XX Figure 1 2 Typical Setup for Calibrating a TEGAM or Weinschel Feedthrough Thermistor Mount Model 1806A Dual Type IV Power Meter Instruction and Service Manual 1 5 Instrument Description DVM or DMM DVM or DMM D
43. r adjustment on this product unless another person capable of rendering first aid is present Use Care When Servicing with Power On or Off Dangerous voltages may exist at several points in this product To avoid personal injury or damage to this equipment avoid touching exposed connections or components while the power is on Assure that the power is off by unplugging the instrument when removing panels soldering or replacing components WARNING The instrument power source is electronically controlled meaning that there is power present throughout the instrument even when the instrument is in the OFF state WARNING Do not wear jewelry rings bracelets metal watches neck chains while working on exposed equipment 2 4 Model 1806A Dual Type IV Power Meter Instruction and Service Manual IEGAM Preparation for Use WARNING Be very cautious about using hand tools near exposed backplanes bus bars or power supply terminals Use properly insulated tools When making test connections to the power supply terminals and bus bars use only insulated probe tips Power Source This product is intended to connect to a power source that the voltage between the supply conductors or between either supply conductor and ground will not apply more than the voltage rating for the particular power supply A protective ground connection by way of the grounding conductor in the power cord is essential for safe operation N Line Voltage Selection
44. r and housing Also ensure that the top and bottom panels align properly with the grooves in the rear panel Model 1806A Dual Type IV Power Meter Instruction and Service Manual Service Information INSTRUMENT DESCRIPTION PREPARATION FOR USE OPERATING INSTRUCTIONS THEORY OF OPERATION MAINTENANCE SERVICE INFORMATION Model 1806A Dual Type IV Power Meter Instruction and Service Manual 6 1 Service nformation Warranty TEGAM Inc warrants this product to be free from defects in material and workmanship for a period of 1 year from the date of shipment During this warranty period if a product proves to be defective TEGAM Inc at its option will either repair the defective product without charge for parts and labor or exchange any product that proves to be defective TEGAM Inc warrants the calibration of this product for a period of 1 year from date of shipment During this period TEGAM Inc will recalibrate any product which does not conform to the published accuracy specifications In order to exercise this warranty TEGAM Inc must be notified of the defective product before the expiration of the warranty period The customer shall be responsible for packaging and shipping the product to the designated TEGAM service center with shipping charges prepaid TEGAM Inc shall pay for the return of the product to the customer if the shipment is to a location within the country in which the TEGAM service center i
45. re and ensure the READY indicator stays illuminated during RF power sensor calibrations ERROR Indicator The ERROR indicator is a red LED that illuminates for any condition preventing the Type IV Bridge circuit from balancing i e an open or short on the BIAS VOLTAGE terminals When the ERROR indicator becomes illuminated stop any calibration and contact TEGAM for assistance RVG Switch The RVG Reference Voltage Generator is a three position switch that is used to turn the RVG ON and OFF The TEST position allows the user to measure the RVG voltage directly BI AS VOLTAGE Connectors The Bias Voltage connectors are spade lug connecting posts banana jacks These connectors complete the DC path between the 1806A Type IV Bridge and the thermistor element The 1806A is designed for use with 200 Ohm thermistors only TEMPerature Connector 4 pin mini microphone connector that is used to connect the heater control circuit to an internal heater found in TEGAM and Weinschel RF Power Transfer Standards TEGAM RF Power Transfer Standards require at least two hours of warm up time to reach their operating temperature Two temperature control cables P N CA 10 48 are supplied with the Model 1806A however a 3 2 Model 1806A Dual Type IV Power Meter Instruction and Service Manual TEGAM Operating Instructions different temperature control cable is needed to connect to TEGAM Models F1125 F1130 and F1135 VOLTMETER Connectors The VOLTMETE
46. reen LED Reference Voltage Generator 2 5 VDC x1 mV Environmental Operating Temperature 12 to 32 C 454 to 90 F Storage Temperature 40 to 75 40 to 167 F Humidity Less than 80 RH non condensing Altitude Sea level to 2000 meters Connectors BI AS VOLTAGE Binding posts 0 75 spacing for banana plugs TEMP 4 pin mini microphone VOLTMETER Binding posts 0 75 spacing for banana plugs Power Requirements 12 Watts 50 to 400 Hz 95 to 125 Vac standard or 210 to 250 Vac with a factory installed option Physical Dimensions Height 3 5 in 89 mm Width 18 in 457 mm Depth 15 4 in 391 mm Model 1806A Dual Type IV Power Meter Instruction and Service Manual 1 3 TEGAM Instrument Description Additional equipment Table 1 2 lists the additional equipment required to measure RF power with the Model 1806A The description for each piece of equipment listed states the minimum recommended requirements for that piece of equipment There may be many models that meet the minimum requirements it is up to the operator to select the specific model Measurement uncertainty will vary depending on the additional equipment used Please refer to the specifications for the particular model number to get that information Table 1 2 Additional Equipment Required Thermistor RF Power Sensor 200 Ohm nominal resistance value Temperature controlled models manufactured by TEGAM Weinschel or temperature compensated m
47. round Switch Test This procedure verifies proper operation of the Float Ground switch located on the Rear Panel of the Model 1806A 1 2 3 Ensure the Model 1806A Front Panel Switch is in the OFF position Remove power cord on the back of the Model 1806A Switch the Float Ground Switch to the Float position Connect Ohmmeter across PS1 T C and the chassis This measurement should indicate an open condition Place the Float Ground Switch to the Ground position Repeat step 4 but now the Ohmmeter should indicate a short condition Place the Float Ground Switch to the Float position Reconnect the power cord to the back of the Model 1806A Model 1806A Dual Type IV Power Meter Instruction and Service Manual 5 5 Maintenance Power Supply Tests This procedure verifies that the power supplies are operating properly and no internal or external component is causing a power supply overload condition Refer to Figure 5 1 for assembly location information Caution The electrical energy present at the power supplies may cause personal injury if directly contacted when the POWER switch is ON Use caution when connecting test equipment leads to the power supplies It is recommended that the POWER switch is set to OFF when connecting or disconnecting test equipment leads to the 1806A power supplies 5 6 1 Set the Model 1806A front panel POWER Switch to the ON position and ensure that the front panel POWER ON Indi
48. s located The customer shall be responsible for paying all shipping duties taxes and additional costs if the product is transported to any other locations Repaired products are warranted for the remaining balance of the original warranty or 90 days whichever period is longer Warranty Limitations The TEGAM Inc warranty does not apply to defects resulting from unauthorized modification or misuse of the product or any part This warranty does not apply to fuses batteries or damage to the instrument caused by battery leakage Statement of Calibration This instrument has been inspected and tested in accordance with specifications published by TEGAM Inc The accuracy and calibration of this instrument are traceable to the National Institute of Standards and Technology through equipment which is calibrated at planned intervals by comparison to certified standards maintained in the laboratories of TEGAM Inc Contact Information TEGAM INC 10 TEGAM WAY GENEVA OHIO 44041 PH 440 466 6100 FX 440 466 6110 EMAIL sales tegam com 6 2 Model 1806A Dual Type IV Power Meter Instruction and Service Manual Service Information Preparation for Repair or Calibration Service Once you have verified that the cause for the Model 1806A malfunction cannot be solved in the field and the need for repair and calibration service arises contact TEGAM customer service to obtain an RMA Returned Material Authorization number
49. se temperature changes will cause this voltage to drift significantly which will affect the power calculation TEGAM and Weinschel thermistor mounts have a heater built into them which controls the temperature of mount The bias voltage of the TEGAM and Weinschel mounts drifts little which means a V4 does not have to be measured for each power level measurement The temperature compensation thermistor beads in the Agilent HP thermistor mounts can be used to compensate for thermal drift in the RF detecting thermistor beads Since the compensating set of thermistor beads is electrically isolated from the detecting set the only change in the bridge voltage would be due to thermal changes When the compensating thermistor beads are used they should be connected to one bridge of the 1806A and the RF power sensing thermistor beads are connected to the other The voltage measured at the VOLTMETER terminals for the bridge monitoring the compensating thermistor beads can be used as V4 This eliminates the need for taking frequent voltage measurements from the detecting thermistor beads with the RF power off RF Power Level Measurement using the RVG Reference Voltage Generator When the applied RF power level becomes small the change in voltage across the bridge also becomes very small In this situation even a high accuracy voltmeter magnifies measurement uncertainties because the large DVM measurement scale has limited resolution Use of the RVG Refere
50. to each bridge at the same time The TEMPerature output of the 1806A is connected the heater input of the TEGAM or Weinschel standard using the heater cable supplied with the 1806A Allow at least 2 hours for the standard to reach operating temperature after connecting the heater the READY indicator will illuminate once the mount has reached its operating temperature The BIAS VOLTAGE red and black binding posts are connected to red and black binding posts on the TEGAM or Weinschel standard Allow at least one hour after the BIAS VOLTAGE terminals are connected before taking any measurements The 1806A VOLTMETER red and black connectors are connected to the DVM DC voltage positive and negative input connectors respectively The BIAS VOLTAGE and VOLTMETER connectors are binding posts banana jacks so banana plugs or spade lugs will mate with them 3 4 Model 1806A Dual Type IV Power Meter Instruction and Service Manual TEGAM Operating Instructions DVM or DMM DVM or DMM BRIDGE A BRIDGE B BIAS BIAS TEMP VQLTMETER TEMP VQLTMETER O READY VOLTAGE READY VOLTAGE ERROR ERROR Vcomp Optional Agilent HP thermistor Figure 3 4 Connections for an Agilent HP Temperature Compensated Thermistor Mount Cable P N 138 652 Figure 3 4 shows the connections for an
51. uced to the thermistor Like all RF power sensors some of the RF power applied to the input of the thermistor sensor is lost by reflection and other causes before it is applied to the thermistor element Thus calibration factor corrections are applied in the following formula to determine the actual level of RF power Pre Pac K Where Pkr Level of applied RF power DC substituted power which is proportional to the applied RF power K calibration factor of thermistor sensor traceable to NIST o 20 V U2 R9 o Ue READY Q4 Figure 4 2 Simplified Schematic of the Model 1806A Heater Circuit Controlling Thermistor Temperature A thermistor is a temperature sensitive device In order to provide precise measurements the effects of changes in the ambient temperature upon the thermistor must be eliminated or minimized The Model 1806A temperature controller accomplishes this by raising the TEGAM or Weinschel power standard s internal temperature to a level higher than the ambient temperature approximately 60 C and maintaining that level by controlling the current applied to the power standard s heater element This prevents any thermistor imbalance due to ambient temperature change Therefore all temperature changes are due to the application of RF and DC power The temperature control circuit performs two basic functions control the temperature of the thermistor element and il
52. uency bandwidth of the thermistor mount The primary application of this system is for power sensor calibration The Model 1806A contains two Type IV Bridge circuits and two thermistor mount temperature controllers Power measurements are derived from DC voltage measurements so a precise and accurate Digital Voltmeter is required The 1806A includes an internal reference voltage generator RVG which can be used as a voltage offset for more precise measurements This becomes increasingly important when measuring power levels below a milliwatt The Model 1806A is designed for use with a temperature stabilized 200 Ohm thermistor mount and a DVM with a 6 5 digit or higher resolution The Model 1806A contains two self balancing Type IV Bridge circuits that pass current through a bolometer mount while sensing the voltage across the mount which defines the resistance of the bolometer at its DC terminals This process eliminates lead errors associated with Wheatstone Bridges Therefore the Model 1806A suits applications such as power measurement and insertion loss measurement applications requiring high accuracy and computer control The role of the Model 1806A within the TEGAM Power Sensor Calibration System is to measure precisely RF and microwave power applied to RF power standards in order to transfer the calibration factor of one standard to another The TEGAM Power Sensor Calibration System is an IEEE Bus compatible system designed to calibrate feedthrou
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