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Tegam F1125, Инструкция по эксплуатации и обслуживанию

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         Theory of Operation 

 

 

Coaxial RF Power Standards Instruction and Service Manual

 

4-3 

 

Controlling Thermistor Temperature 

Since thermistor mounts are temperature sensitive devices, it is necessary to eliminate or 

minimize the effects of changes in the ambient temperature. This is accomplished by thermally 

isolating the mount, raising its temperature with a heater element to a level higher than the 

ambient temperature, and maintaining that level by means of an external temperature controller. 

The heater element electrical assembly, illustrated in Figure 4.2, is a Wheatstone bridge 

configuration composed of wiring wound around a thermal mass. 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. The proper 

temperature is determined by the characteristics of the thermistor beads. The 2K-ohm 

potentiometer is used to adjust the temperature such that the bead bias power (with no RF power 

applied) is 30mW ± 0.7 mW. An external controller drives the heater. 

The Heater Bridge circuit shown in Figure 4.2 balances when all the heater windings are equal in 

resistance. 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). In an unbalanced condition, the bridge output 

controls the current output of a temperature controller. Hence, the bridge configuration 

accomplishes both a temperature sensing and heating function. 

 

Bias

Voltage

Adjust

R1

R4

R3

R2

1

4

3

2

 

Figure 4.2 Simplified Schematic of RF Power Standards Internal Heater 

 

Principle of DC Substitution 

The RF Power Standards use 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. 

Since some of the RF power applied to the input of the power standard is lost by reflection and 

other causes before it is applied to the thermistor element, a calibration factor for the standard is 

applied by the following formula to determine the actual level of RF power: 

P

RF

 

= P

dc 

        K

 

Where: 

P

RF

 

= Level of applied RF power, 

P

dc

 = DC substituted power which is proportional to the RF power incident on the thermistor 

beads, 

K = calibration factor of the RF Power Standard traceable to NIST 

 

TEGAM Coaxial RF Power Standards are configured to provide a path for RF energy via a coaxial 

line. DC Bias is introduced from the Bias terminals to the thermistors via filtering capacitors. 

Содержание F1125

Страница 1: ...MODELS F1125 A F1130 A B F1135 A B M1125 A M1130 A M1135 A Coaxial RF Power Standards Instruction and Service Manual PN IM300 Publication Date April 2015 REV R ...

Страница 2: ...del M1135 Model F1135 Instruction and Service Manual PN IM300 Publication Date April 2015 REV R 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 ...

Страница 3: ...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 informati...

Страница 4: ... Standard Model F1125 F1130 F1135 1 8 Figure 1 5 Measuring a 50 MHz Reference Output on a Power Meter using a Primary Transfer Standard Model M1125 M1130 M1135 1 9 Figure 1 6 Calibration of a Working Transfer Standard using a Primary Transfer Standard 1 9 II PREPARATION FOR USE 2 1 Unpacking Inspection 2 2 Mounting 2 2 Safety Information Precautions 2 2 Terms in this Manual 2 2 Terms as Marked on ...

Страница 5: ...Rear Panel Screws 5 3 Power Splitter Calibration 5 3 Figure 5 2 Location of Power Splitter in the F1125 F1130 and F1135 5 3 Figure 5 3 Location of Allen Head Screws and Collar on F1125 and F1130 5 4 Figure 5 4 Location of Phillips Head Screws on F1135 Splitter Support Bracket 5 5 Thermistor Bias Voltage Calibration 5 6 Figure 5 5 Location of Bias Adjustment 5 7 Calibration Factor 5 7 Figure 5 6 Co...

Страница 6: ...Instrument Description Coaxial RF Power Standards Instruction and Service Manual 1 1 INSTRUMENT DESCRIPTION PREPARATION FOR USE OPERATING INSTRUCTIONS THEORY OF OPERATION MAINTENANCE SERVICE INFORMATION ...

Страница 7: ...manual Abbreviations and acronyms that are not listed conform to MIL STD 12D CW Continuous Wave DUT Device Under Test DMM Digital Multi Meter DVM Digital Voltmeter ESDS Electrostatic Discharge Sensitive NIST National Institute of Standards and Technology RF Radio Frequency DC Direct Current Figure 1 1 Models M1125 F1125 Figure 1 2 Models M1130 F1130 Figure 1 3 Models M1135 F1135 ...

Страница 8: ...r Figure 1 5 Physical Description Refer to Table 1 1 for the general specifications for the RF Power Standards The Working RF Power Standards feature a SENSOR RF INput BIAS VOLTAGE and TEMPerature connectors on the front panel The Reference RF Power Standards feature an RF INput connector on the front and BIAS VOLTAGE and TEMPerature connectors in the rear The Working RF Power Standards can be mou...

Страница 9: ...racy typical 0 80 from 0 1 to 10 MHz 0 90 from 10 to 4200 MHz 1 0 from 0 1 to 10 MHz 1 1 from 10 to 4200 MHz Connectors SENSOR RF IN TEMP BIAS VOLTAGE N type Female SMA Female 4 pin mini microphone Binding Post standard 0 75 spacing for banana plugs N A N Type Male 4 pin microphone Binding Post standard 0 75 spacing for banana plugs Weight 5 5 lbs 2 5 kg 2 88 lbs 1 3 kg Physical Dimensions Height ...

Страница 10: ...to 10 GHz 1 10 from 10 to 18 GHz 1 0 from 0 1 to 10 MHz 1 20 from 0 01 to 10 GHz 1 30 from 10 to 18 GHz Connectors SENSOR RF IN TEMP BIAS VOLTAGE N type Female SMA Female 4 pin mini microphone Binding Post standard 0 75 spacing for banana plugs N A N Type Male 4 pin microphone Binding Post standard 0 75 spacing for banana plugs Weight B Model 5 5 lbs 2 5 kg 8 2 lbs 3 7 kg 3 22 lbs 1 5 kg Physical ...

Страница 11: ...7 5 GHz 2 5 from 17 75 to 26 5 GHz 1 2 from 0 01 to 0 04 GHz 1 4 from 0 05 to 4 0 GHz 1 7 from 4 20 to 12 0 GHz 2 3 from 12 2 to 17 5 GHz 2 6 from 17 75 to 26 5 GHz Connectors SENSOR RF IN TEMP BIAS VOLTAGE 3 5 mm Female SMA Female 4 pin mini microphone Binding Post standard 0 75 spacing for banana plugs N A 3 5 mm Male older version may have 2 92 mm 4 pin microphone Binding Post standard 0 75 spa...

Страница 12: ...dards 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 i...

Страница 13: ...nd Service Manual 1 8 BIAS VOLTAGE TEMPERATURE Model 1805B AM Out rear of 1805B AM Input RF Output Signal Generator BIAS VOLTAGE RF IN TEMP IN SENSOR Model F11XX DUT Power Meter Figure 1 4 RF Power Sensor Calibration Using a Working Standard Model F1125 F1130 F1135 ...

Страница 14: ...ing a 50 MHz Reference Output on a Power Meter using a Terminating RF Power Standard Model M1125 M1130 M1135 BIAS VOLTAGE TEMPERATURE Model 1805B AM Out rear of 1805B AM Input RF Output Signal Generator BIAS VOLTAGE RF IN TEMP IN SENSOR Model F11XX Model M11XX BIAS VOLTAGE TEMP Model 1806 VOLTMETER BIAS VOLTAGE TEMP VOLTMETER BRIDGE A BRIDGE B DVM or DMM V V Figure 1 6 Calibration of a Working Pow...

Страница 15: ...Preparation for Use Coaxial RF Power Standards Instruction and Service Manual 2 1 INSTRUMENT DESCRIPTION PREPARATION FOR USE OPERATING INSTRUCTIONS THEORY OF OPERATION MAINTENANCE SERVICE INFORMATION ...

Страница 16: ... also be rack mounted in a standard 19 rack using the optional rack mount kit F1120 RMK For Model F1130B and F1135B use rack mount kit Single P N 1830 910 Dual P N 1830 911 The Model M1125 M1130 and M1135 are shipped with four adjustable feet fastened to the base of the unit Not only are these feet used to support the instrument they are used to adjust the height of the instrument to ensure the ma...

Страница 17: ...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 RF Power Standards have a specified ambient temperature range of 12 to 40 C 54 to 104 F Operating beyond these limits can affect the accuracy of the instruments and damage internal circuitry CAUTION When an RF Power Standard i...

Страница 18: ...ne Do not perform service or 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 disconnecting th...

Страница 19: ...Operating Instructions Coaxial RF Power Standards Instruction and Service Manual 3 1 INSTRUMENT DESCRIPTION PREPARATION FOR USE OPERATING INSTRUCTIONS THEORY OF OPERATION MAINTENANCE SERVICE INFORMATION ...

Страница 20: ...806 A 1805B and 1830A Model F1125 F1130 and F1135 Connector Descriptions Figure 3 1 Model F1125 Front View RF IN connector SMA female connector that connects to signal generator output The RF power that comes in this connector is applied equally to the DUT and the power standard The fact that equal RF power is applied to both the power standard and the DUT is what allows the determination the cali...

Страница 21: ... heater to a heater control circuit found in TEGAM Models 1805B 1806 A 1830A and 1820 RF Power Standards require at least two hours of warm up time to reach their operating temperature This connector is compatible with the heater control cable supplied with Models 1805B 1806 1830A and 1820 BIAS VOLTAGE connectors Binding posts used to connect the thermistor element to a DC Substitution bridge circ...

Страница 22: ...nectors of the standards are 5 way binding posts so banana plugs or spade lugs can be used See the mating equipment instruction manual for the correct Bias Voltage cable part number The RF IN on the Working Feedthrough Power Standards Models F1125 F1130 F1135 is an SMA female coaxial connector that is connected to the output of the chosen signal generator which should be 50 Ohm nominal impedance A...

Страница 23: ...Theory of Operation Coaxial RF Power Standards Instruction and Service Manual 4 1 INSTRUMENT DESCRIPTION PREPARATION FOR USE OPERATING INSTRUCTIONS THEORY OF OPERATION MAINTENANCE SERVICE INFORMATION ...

Страница 24: ...re coefficient of the beads Initially the beads are DC biased to 200 ohms Application of RF power increases the power level present at the beads and causes the effective resistance value of the beads to drop The Type IV bridge circuit reduces DC power until the initial effective resistance value is restored 200 ohms The total amount of DC power removed is proportional to the amount of RF power tha...

Страница 25: ...ero 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 In an unbalanced condition the bridge output controls the current output of a temperature controller Hence the bridge configuration accomplishes both a temperature sensing and heating function Bias Voltage Adjust R1 R4 R3 R2 1 4 3 ...

Страница 26: ...sion resistance leg when RF power is applied to the thermistor leg P1 power across the precision resistance leg without RF power applied P2 power across the precision resistance leg with RF power applied By substituting for P1 and P2 from the previous formula P V1 2 V2 2 200 200 Combining terms P V1 2 V2 2 200 Where P the change in power of the precision resistance leg when RF power is applied to ...

Страница 27: ...ting RF Power Standard traceable to NIST The system determines the calibration factor of the tested mount in terms of the known calibration factor of the previously calibrated thermistor mount and the precision measurement of the substituted DC power The Feedthrough RF Power Standard is used to determine the calibration factor for other terminating powers sensors The calibration factor for a Devic...

Страница 28: ...ing the Feedthrough Power Standard the power splitter is removed and its reflection coefficient is measured with a network analyzer The power splitter is replaced in the Feedthrough Power Standard assembly and the reflection coefficient of the sensor port of the power splitter is the reflection coefficient for the entire assembly Since the Feedthrough Power Standard is actually calibrated as an as...

Страница 29: ...tion factor of the Feedthrough RF Power Standard K1S calibration factor of the DUT Γ1 reflection coefficient of the Terminating RF Power Standard Γ2 reflection coefficient of the Feedthrough RF Power Standard Γ1S reflection coefficient of the DUT The Gamma Correction part of the previous equations can be rewritten in terms of reflection coefficient magnitude ρ and angle φ 1 ρ1ρ2 cos φ1 φ2 2 ρ1ρ2 s...

Страница 30: ...Maintenance Coaxial RF Power Standards Instruction and Service Manual 5 1 INSTRUMENT DESCRIPTION PREPARATION FOR USE OPERATING INSTRUCTIONS THEORY OF OPERATION MAINTENANCE SERVICE INFORMATION ...

Страница 31: ...pe IV Power Meter or equivalent Nominal Bridge Resistance Bridge Accuracy 200 Ohms 0 003 CW RF Signal Source Frequency Range Power Output Same as the Power Standard being calibrated 6 dBm minimum up to 16 dBm 13 16 Torque Wrench Torque Value 14 1 in lbs for N type connectors 5 16 Torque Wrench Torque Value 7 8 in lbs for SMA and 3 5 mm connectors 9 64 7 64 and 5 64 Allen Hex Wrench 1 and 2 Philips...

Страница 32: ...f the Working RF Power Standard and verifies it is within specification While a Scalar Network Analyzer can be used TEGAM recommends a Vector Network Analyzer be used to measure not only the magnitude but also phase of the reflection coefficient that data can be used later to apply Gamma corrections to the cal factor of the Standard 1 Disconnect all cables from rear of the Thermistor Mount Assembl...

Страница 33: ...tions of Allen Head Screws and Collar on F1125 and F1130 a For Models F1125 and F1130 Type N connectors Refer to figure 5 3 Remove 2 Allen head screws that clamp power splitter input to Splitter Support Bracket Remove collar that is over the thermistor mount output connector by loosening two set screws and sliding the collar forward Then loosen the nut on the type N male connector NOTE The F1130 h...

Страница 34: ...e power splitter and thermistor mount Use care when connecting and disconnecting all coaxial connectors and use proper torque wrench when connecting 4 Terminate Output Port 3 of the power splitter Connect Input Port 1 and Output Port 2 to the network analyzer to measure insertion loss S21 and the reflection coefficient of Port 2 S22 Record these measurements for each calibration frequency The inse...

Страница 35: ... SureCal dat file for the Working Standard 9 Reassemble the power splitter to the thermistor mount Make sure all coaxial RF connectors are properly torqued The type N connectors should be torqued to 14 1 in lbs and the 3 5 mm connectors to 7 8 in lbs 10 Slide the Thermistor Mount Assembly toward the front of case making sure the splitter output port that is the SENSOR port is all the way through t...

Страница 36: ... Bias Voltage has been adjusted to 2 45 V replace the plug in the Bias Voltage Adjustment access hole Calibration Factor This test characterizes the calibration factor of the Working Power Standards F1125 F1130 and F1135 The Working standard is characterized from the SENSOR port using a Reference Power Standard M1125 M1130 or M1135 This procedure can be automated using SureCAL Automated Metrology ...

Страница 37: ...n the connectors Once a good connection has been made adjust the feet of the Reference Standard while still supporting with the other hand so they will hold the weight Make sure RF connectors are clean and use proper torque wrench to tighten 4 Connect Signal Generator output to the input of the Working Feedthrough Power Standard refer to Figure 5 6 Make sure RF connectors are clean and use proper ...

Страница 38: ... nominal power level setting of 6 dBm on the Signal Generator will provide approximately 0 dBm 1 mW at the SENSOR port of the Working Standard That is due to losses in the coaxial power splitter cables and adapters This level can be adjusted according to actual losses which can be determined by measurements made from the Reference Power Standard It is recommended the level at the SENSOR port be ke...

Страница 39: ... Corrected K2 K2 1 Γ1Γ2 2 Where Corrected K2 cal factor of the Working Standard after Gamma correction is applied K2 cal factor of the Working Standard before Gamma correction is applied Γ1 reflection coefficient of the Reference Power Standard Γ2 reflection coefficient of the Working Standard The same formula in terms of magnitude ρ and phase angle φ Corrected K2 K2 1 ρ1ρ2 cos φ1 φ2 2 ρ1ρ2 sin φ1...

Страница 40: ...Service Information Coaxial RF Power Standards Instruction an Service Manual 6 1 INSTRUMENT DESCRIPTION PREPARATION FOR USE OPERATING INSTRUCTIONS THEORY OF OPERATION MAINTENANCE SERVICE INFORMATION ...

Страница 41: ...r the return of the product to the customer if the shipment is to a location within the country in which the TEGAM service center is 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 ...

Страница 42: ...o metal filing or residue remains inside the connector and the connector is thoroughly dry Where rust corrosion and or oxide deposits are present in large quantities replace the connector Calibration Since the stability of the calibration factor of a thermistor mount depends upon the extent of use degree of temperature stability and care in handling TEGAM recommends recalibration of the standard e...

Страница 43: ...trument 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 type of sensor being tested what is the voltage across the bias terminals when RF power is not applied what device was the Standard connected to is the problem intermittent when is the...

Страница 44: ...air process RMA Instrument Model Serial Number Company Technical Contact Phone Number Additional Contact Info Repair Instructions Evaluation Calibration Only Repair Only Repair Calibration 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 is the problem most f...

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