Giga-tronics Sensor Care Training AN-9909 Giga-tronics Sensor Care1Copyright © 2009 Giga-tronics Incorporated. All Rights Reserved

1

Giga-tronics Sensor Care Training

AN-9909 Giga-tronics Sensor Care Copyright © 2009 Giga-tronics Incorporated. All Rights Reserved.

2

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.

3

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



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



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



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



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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• 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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• 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




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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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Low Power Measurements

• Start from low power setting

• “Zero” meter to the source

• Lowest 15 dB dynamic range



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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)



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Measurement Uncertainty:

Sensor / Source Mismatch



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• 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



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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




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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




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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




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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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Breakdown of Failures



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• Center Pin Failure is the most common failure




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Center Pin Failure



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• ESD Precautions

• DC Levels in RF Path

• Maximum Power Ratings



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ESD Control

• Observe ESD Precautions

• Never touch center pin




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Physical Care and Handling

• Handling Giga-tronics Sensors

• Inspecting and Cleaning Sensor Connectors

• Making a Proper Connection



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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




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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




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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





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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



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• First Step• Compressed Air

– Filtered– Vapor and Oil Free– <60 PSI

• High velocity air can generate Electrostatic effects on the connectors




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• 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.


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• 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!




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• Center Conductor• Use EXTREME caution• Moisten cloth with

Isopropyl Alcohol

• Never apply pressure to inner conductor




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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




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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




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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




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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




42AN-9909 Giga-tronics Sensor Care


www.gigatronics.com | 800.726.4442 | [email protected]

Documents

Giga-tronics Sensor Care Training AN-9909 Giga-tronics Sensor Care1Copyright © 2009 Giga-tronics Incorporated. All Rights Reserved