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Giga-tronics Sensor Care Training
AN-9909 Giga-tronics Sensor Care Copyright © 2009 Giga-tronics Incorporated. All Rights Reserved.
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Giga-tronics Sensor Care Training
• Product Overview• Making Accurate Measurements• Sensor Failures at Northrop-Grumman• Physical Care and Handling• Questions and Answers
AN-9909 Giga-tronics Sensor Care
Copyright © 2009 Giga-tronics Incorporated. All Rights Reserved.
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Product Overview
• What are Power Sensors?– Devices rectify RF energy to a DC voltage.– Diode and Thermal Sensors
• Giga-tronics uses Diode Sensors• All Giga-tronics Sensors are DC Coupled
Vdc
0
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• Diode Sensor Advantage– Thermal sensors respond slowly– Fast - capable of tracking rapid power
changes– Measure peak modulated power when
designed with proper video bandwidth
Vdc
0
AN-9909 Giga-tronics Sensor Care
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Product Overview
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• Square Law region from -70 to -20 dBm• Non-linear characteristics from -30 to +20 dBm identified
during calibration and corrected during measurement
Powerin
Square Law Region
Non-Linear Region
Characterization during calibration
-70dBm -20dBm +20dBm
Vout
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Copyright © 2009 Giga-tronics Incorporated. All Rights Reserved.
Product Overview
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• Giga-tronics Sensor Calibration Techniques
Programmable 1 dB steps
DAC
Thermistor ADC
Programmable Atten.
Thermistor used in a patented swept power bridge circuit provides NIST-traceable 90 dB dynamic range
AN-9909 Giga-tronics Sensor Care
Copyright © 2009 Giga-tronics Incorporated. All Rights Reserved.
Product Overview
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• Connector Types– 18 GHz
• Type N• Type K, True RMS and 1 Watt Models only• APC 7
– 26 and 40 GHz• Type K
AN-9909 Giga-tronics Sensor Care
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Product Overview
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Sensor Specifications
• 10 MHz to 40 GHz (Sensor Dependent)– 100 kHz Frequency Range w/ Option 10
• Maximum Power to 50 Watts (47 dBm)• Continuous Amplitude Signals Only• Connector Types
– Type N to 18 GHz– Type K to 40 GHz
80300A CW Sensor Series
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Sensor Specifications
• 45 MHz to 40 GHz (Sensor Dependent)• CW and Pulsed RF Applications• Rise Time
– 100 nsec., 75 nsec. typical– 50 nsec., 40 nsec. typical with Configuration
418• Settling Time - 250 nsec. (50% to 3%)• Sample Delay - -20 nsec. to 104 msec.
80350A Peak Sensor Series
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Sensor Specifications
• 10 MHz to 18 GHz• Video Bandwidths
– 40 kHz 80400A series– 1.5 MHz 80600A series– 10 MHz 80700A series
• Connector Types– Type N to 18 GHz
Modulation Sensor Series
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Power Measurement Accuracy
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• 8 Factors considered when calculating measurement uncertainty:
– Instrumentation linearity – Sensor power linearity– Calibrator uncertainty– Calibrator/sensor mismatch– Calibration factor uncertainty– Zero Error– Noise – Mismatch sensor/source
AN-9909 Giga-tronics Sensor Care
Copyright © 2009 Giga-tronics Incorporated. All Rights Reserved.
Power Measurement Accuracy
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Making Accurate Measurements
Sources of Measurement Errors
• Not Zeroing the meter for low power measurements
• VSWR • Changes in temperature• Exceeding Sensor Video Bandwidth
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Copyright © 2009 Giga-tronics Incorporated. All Rights Reserved.
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Power Measurement Accuracy
Low Power Measurements
• Start from low power setting
• “Zero” meter to the source
• Lowest 15 dB dynamic range
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Power Measurement Accuracy
Measurement Uncertainty: Noise• Zero Error• Meter noise floor• Significant in the last 15 dB of dynamic
range– e.g. Noise specification= +/- 50 pW (-73
dBm), Signal measured = -63 dBm (0.5 nW)
Noise Error = 50pW / 0.5 nW = 10% (0.4 dB)
AN-9909 Giga-tronics Sensor Care
Copyright © 2009 Giga-tronics Incorporated. All Rights Reserved.
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Measurement Uncertainty:
Sensor / Source Mismatch
AN-9909 Giga-tronics Sensor Care
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Making Accurate Measurements
• Exceeding Sensor Video Bandwidth
Two Tone Measurement8650A w/ 80401A
Modulated Average Power
-0.1
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
-60 -50 -40 -30 -20 -10 0
Absolute Power
Po
wer
dB
r r
ela
tive t
o t
wo
890 M
Hz s
ign
als
0 Hz bandwidth
40 kHz bandwidth
8 MHz bandwidth
AN-9909 Giga-tronics Sensor Care
Copyright © 2009 Giga-tronics Incorporated. All Rights Reserved.
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DC Levels in the RF Path
• All Giga-tronics Sensors are DC coupled
• RF source must not have DC present on output
AN-9909 Giga-tronics Sensor Care
Copyright © 2009 Giga-tronics Incorporated. All Rights Reserved.
Making Accurate Measurements
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Maximum Power Ratings
• All Diode Sensors have a maximum rating of +23 dBm (200 mW)
• Rating applies for CW and Peak Levels
• High Power Sensors use Attenuators to reduce the power to the diode element
AN-9909 Giga-tronics Sensor Care
Copyright © 2009 Giga-tronics Incorporated. All Rights Reserved.
Making Accurate Measurements
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Sensor Failure Types:
•Miscellaneous
• Operational/Test• Physical
Damage
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Sensor Failures at Northrop-Grumman
• Operational Failures– All Diode Sensors have a maximum rating of
+23 dBm (200 mW)• Electrical Damage to Diode Elements
– Exceeding +23 dBm at diode element– ESD– DC level on RF output
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• Physical Failures– Excessive shear force– Worn Connectors
• Instrument Grade vs. Product Grade– Stress to Center Pin– Dropped sensor– Dirty Connectors– Improper connection and disconnections– Exceeding the recommended torque
AN-9909 Giga-tronics Sensor Care
Copyright © 2009 Giga-tronics Incorporated. All Rights Reserved.
Sensor Failures at Northrop-Grumman
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• Other Failures–Failed EEPROM
• +5 Volt Supply Failure– Using Agilent/HP Sensor Cables
• Accidental Erasure of Sensor Data– Internal Damage
• Production Assembly
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Copyright © 2009 Giga-tronics Incorporated. All Rights Reserved.
Sensor Failures at Northrop-Grumman
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Breakdown of Failures
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• Center Pin Failure is the most common failure
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Sensor Failures at Northrop-Grumman
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Center Pin Failure
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Making Accurate Measurements
• ESD Precautions
• DC Levels in RF Path
• Maximum Power Ratings
AN-9909 Giga-tronics Sensor Care
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ESD Control
• Observe ESD Precautions
• Never touch center pin
AN-9909 Giga-tronics Sensor Care
Copyright © 2009 Giga-tronics Incorporated. All Rights Reserved.
Making Accurate Measurements
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Physical Care and Handling
• Handling Giga-tronics Sensors
• Inspecting and Cleaning Sensor Connectors
• Making a Proper Connection
AN-9909 Giga-tronics Sensor Care
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• Observe ESD precautions at all times!• Know the approximate levels being tested• Do not place sensors in locations where
they can be easily dropped• Never strain sensor body once connected• Do not leave long sensor cables on the
ground
Handling Giga-tronics Sensors
AN-9909 Giga-tronics Sensor Care
Copyright © 2009 Giga-tronics Incorporated. All Rights Reserved.
Physical Care and Handling
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• Dirty Connectors– Connector Degradation, Measurement
Repeatability, Accuracy, Connector Life• Inspect connectors
– Every 20 connections– Inspect sensor and device connectors for
signs of damage and wear– Dirt and Metal Flakes
Cleaning Sensor Contacts
AN-9909 Giga-tronics Sensor Care
Copyright © 2009 Giga-tronics Incorporated. All Rights Reserved.
Physical Care and Handling
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Cleaning Sensor Contacts• Visual Inspection
– Damage and dirt can significantly degrade repeatability and accuracy
– Gold plated surfaces are especially sensitive to connector damage
– Dents, burrs, metal particles, rough spots, and damaged threads
– Bent or damaged inner conductor• Never use a damaged connector
AN-9909 Giga-tronics Sensor Care
Copyright © 2009 Giga-tronics Incorporated. All Rights Reserved.
Physical Care and Handling
Copyright © 2009 Giga-tronics Incorporated. All Rights Reserved.
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Cleaning Sensor Contacts• Visual Inspection
If the connector has the following:– Deep scratches– Dents– Particles clinging to mating plane
surfaces– Uneven wear
Clean connector and re-inspect
AN-9909 Giga-tronics Sensor Care
Physical Care and Handling
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Cleaning Sensor Contacts
• First Step• Compressed Air
– Filtered– Vapor and Oil Free– <60 PSI
• High velocity air can generate Electrostatic effects on the connectors
AN-9909 Giga-tronics Sensor Care
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Physical Care and Handling
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Cleaning Sensor Contacts
• Second Step• Cotton Swab moistened
with Isopropyl Alcohol– Clean outer surfaces only
• Do not saturate the swab
with Isopropyl Alcohol• Never make contact with the
innerconductor!AN-9909 Giga-tronics Sensor
CareCopyright © 2009 Giga-tronics Incorporated. All Rights Reserved.
Physical Care and Handling
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Cleaning Sensor Contacts
• Third Step• Lint free cloth wrapped
around an applicator• Moisten only
• Do not saturate the cloth
with Isopropyl Alcohol• Never make contact with the
centerconductor!
AN-9909 Giga-tronics Sensor Care
Copyright © 2009 Giga-tronics Incorporated. All Rights Reserved.
Physical Care and Handling
37
Cleaning Sensor Contacts
• Center Conductor• Use EXTREME caution• Moisten cloth with
Isopropyl Alcohol
• Never apply pressure to inner conductor
AN-9909 Giga-tronics Sensor Care
Copyright © 2009 Giga-tronics Incorporated. All Rights Reserved.
Physical Care and Handling
38
Cleaning Sensor Contacts• Don’ts
– Use Acetone, Methanol or CFC’s– Overuse Isopropyl Alcohol– Wet any plastic parts (dielectrics) in
connectors– Make contact with the center conductor– Use a swab larger than the gap between the
inner and outer conductors– Blow on a connector
AN-9909 Giga-tronics Sensor Care
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Physical Care and Handling
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• Align the sensor connector straight in line with mating device connector
• Turn the Connector Body Only– Never turn the sensor body or source
connector– Gold plating wear
• Hold the sensor stable while connecting and disconnecting the sensor
Tightening a Sensor Connector
AN-9909 Giga-tronics Sensor Care
Copyright © 2009 Giga-tronics Incorporated. All Rights Reserved.
Physical Care and Handling
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• Too much torque will damage a sensor connector
• Use a Torque Wrench whenever possible• Tighten using thumb and forefinger only• Recommended Torque
– Type N 12 – 15 in-lbs.– Type K 8 in-lbs.
Tightening a Sensor Connector
AN-9909 Giga-tronics Sensor Care
Copyright © 2009 Giga-tronics Incorporated. All Rights Reserved.
Physical Care and Handling
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• Never use wrenches or pliers to tighten connector
• Use “Soft Jaw” Pliers and Channel Locks to remove “stuck” connectors only
Connector Torque
AN-9909 Giga-tronics Sensor Care
Copyright © 2009 Giga-tronics Incorporated. All Rights Reserved.
Physical Care and Handling
42AN-9909 Giga-tronics Sensor Care
Copyright © 2009 Giga-tronics Incorporated. All Rights Reserved.
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