Agilent Technologies 8481A Service manual

Operating and Service Manual
Agilent 8480 Series Coaxial Power Sensors
This manual applies to the following models:
8481A
8482A
8483A
8485A
8487A
8481B
8482B
8481H
8482H
8487D
8485D
8481D
Manufacturing Part Number: 08481-90173
March 15, 2012
© Copyright 2003-2012 Agilent Technologies.

A
Document Part Number 5971-2668
Printed in the UK December 2010
Errata
This manual may contain references to HP or Hewlett-Packard. Please note that Hewlett-Packard's former test
and measurement, semiconductor products and chemical analysis businesses are now part of Agilent
Technologies. To reduce potential confusion, the only change to product numbers and names has been in the
company name prefix: where a product number/name was HP XXXX the current name/number is now Agilent
XXXX. For example, model number HP8648 is now model number Agilent 8648.
Ce manuel peut contenir des références à <<HP>> ou <<Hewlett-Packard.>> Veuillez noter que les produits de
test et mesure, de semi-conducteur et d'analyse chimique qui avaient fait partie de la société Hewlett-Packard
sont maintenent une partie de la société Agilent Technologies. Pour reduire la confusion potentielle, le seul
changement aux noms de reference a été dans le préfixe de nom de société : là où un nom de référence était HP
XXXX, le nouveau nom de référence est maintenant Agilent XXXX. Par example, le HP 8648 s'appelle
maintenent Agilent 8648.
Diese Gebrauchsanweiseung kann Bezug nehmen auf die Namen HP oder Hewlett-Packard. Bitte beachten Sie,
dass ehemalige Betriebsbereiche von Hewlett-Packard wie HP-Halbleiterprodukte, HP-chemische Analysen
oder HP-Test- und Messwesen nun zu der Firma Agilent Technology gehören. Um Verwirrung zu vermeiden
wurde lediglich bei Produktname und - Nummer der vo laufende Firmenname geändert: Produkte mit dem
Namen/Nummer HP XXXX lauten nun mehr Agilent XXXX. Z.B, das Modell HP 8648 heißt nun Agilent 8648.
Questo manuale potrebbe contenere riferimenti ad HP o Hewlett-Packard. Si noti che le attività precedentemente
gestite da Hewlett-Packard nel campo di Test & Misura, Semiconduttori, ed Analisi Chimica sono ora diventate
parte di Agilent Technologies. Al fine di ridurre il rischio di confusione, l'unica modifica effettuata sui numeri di
prodotto e sui nomi ha riguardato il prefisso con il nome dell'azienda : dove precedentemente compariva "HP
XXXX" compare ora "Agilent XXXX". Ad esempio: il modello HP8648 è ora indicato come Agilent 8648.
Este manual puede hacer referencias a HP o Hewlett Packard. Las organizaciones de Prueba y Medición (Test
and Measurement), Semiconductores (Semiconductor Products) y Análisis Químico (Chemical Analysis) que
pertenecían a Hewlett Packard, ahora forman parte de Agilent Technologies. Para reducir una potencial
confusión, el único cambio en el número de producto y nombre, es el prefijo de la compañía: Si el producto solía
ser HP XXXX, ahora pasa a ser Agilent XXXX. Por ejemplo, el modelo HP8648 es ahora Agilent 8648.
5971-2668 Small.fm Page 1 Wednesday, September 22, 2004 2:20 PM

マニュアル・チェンジ
変更
本文中の「HP（YHP）」、または「(横河)ヒューレット・パッカード株式会社」とい
う語句を、「Agilent」、または「アジレント・テクノロジー株式会社」と変更して
ください。
ヒューレット・パッカード社の電子計測、半導体製品、化学分析ビジネス部門は分
離独立し、アジレント・テクノロジー社となりました。
社名変更に伴うお客様の混乱を避けるため、製品番号の接頭部のみ変更しておりま
す。
（例: 旧製品名 HP 4294A は、現在 Agilent 4294A として販売いたしておりま
す。）

ii
Notice
The information contained in this document is subject to change without notice.
Agilent Technologies makes no warranty of any kind with regard to this material,
including but not limited to, the implied warranties of merchantability and fitness
for a particular purpose. Agilent Technologies shall not be liable for errors contained
herein or for incidental or consequential damages in connection with the furnishing,
performance, or use of this material.
All Rights Reserved. Reproduction, adaptation, or translation without prior written
permission is prohibited, except as allowed under the copyright laws.
5301 Stevens Creek Blvd. Santa Clara, CA 95052 USA

iii
Warranty
A copy of the specific warranty terms applicable to your Agilent Technologies
product can be obtained from your local Sales and Service Office.
Manufacturer's Declaration
This statement is provided to comply with the requirements of the German Sound
Emission Directive, from 18 January 1991.
This product has a sound pressure emission (at the operator position)
<70dB(A).
Diese Information steht im Zusammenhang mit den Anforderungen der
Maschinenlärminformationsverordnung vom 18 Januar 1991.
• Sound Pressure Lp < 70 dB(A).
• At Operator Position.
• Normal Operation.
• According to ISO 7779:1988/EN 27779:1991 (Type Test).
Hersteller-
bescheinigung
• Schalldruckpegel Lp < 70 dB(A).
• Am Arbeitsplatz.
• Normaler Betrieb.
• Nach ISO 7779:1988/EN 27779:1991 (Typprüfung).

iv

Contents
1
1. Introduction
General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2
Instruments Covered by Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2
Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
8480 series, B-models information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
Safety Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
8480 series, Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
8485A and 8485D option 033. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Accessories Supplied . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
8483A 75 ohm sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
D-model 8480 series sensors (8481D, 8485D, 8485D-033 and 8487D).7
26.5 GHz and 33 GHz Frequency operation (8485A, 8485A-033, 8485D and
8485D-033). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
50 GHz Frequency operation (8487A and 8487D). . . . . . . . . . . . . . . . . . . . . . .9
Recommended Calibration Interval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
8480 Series Power Sensor Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Supplemental Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
Initial Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
Original Packaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
Interconnections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
Storage and Shipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
Operating Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
Power Meter Calibrations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
Operating Instructions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21

2
Contents
Power Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Modulation Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2. General Information
Recommended Test Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Connector Care . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Torque . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Performance Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Standing Wave Ratio (SWR) and Reflection Coefficient (Rho) Performance Test.
26
Replaceable Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
3. Service
Principles of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Thermocouple Sensors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Diode Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Troubleshooting - Eliminating the Power Meter and Sensor Cable . . . . . . . . . . 40
Troubleshooting - Power Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
A1 Bulkhead (Thermocouple Sensors) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
A1 Bulkhead (Diode Sensors) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
A2 Power Sensor Board Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Repair. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
A1 Bulkhead Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Repair Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
A2 Power Sensor Board Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Repair Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

Contents
3
FET Balance Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45
Equipment Required. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45
Test Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45
FET Balance Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46
Disassembly / Reassembly Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .49
Disassembly Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .49
Reassembly Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51
A. EPM Series Power Meter (E4418B) Modification
The Material and Tools Required. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .54
Impact on Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .54
Modification Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55
B. Bulkhead Assemblies
Bulkhead Parts Lists. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .62
Bulkhead Exploded Graphics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .69

4
Contents

Chapter 1 1
1Introduction
This Operating and Service Manual contains information about initial inspection,
performance tests, adjustments, operation, troubleshooting and repair of the Agilent
8480 Series Coaxial Power Sensors.

Introduction
Chapter 12
General Information
Instruments Covered by Manual
A serial number label is attached to the power sensor. The serial number has two
parts: the prefix (two letters and the first four numbers), and the suffix (the last four
numbers). Refer to the Example Serial Number shown in Figure 1-1.
Figure 1-1 Example Serial Number
The two letters identify the country in which the unit was manufactured. "US"
represents the USA and "MY" represents Malaysia. The four numbers of the prefix
are a code identifying the date of a major design change incorporated in your power
sensor. The four digit suffix is a sequential number and, coupled with the prefix,
provides a unique identification for each unit produced.
When seeking information about your power sensor refer to the complete serial
number and include the full prefix number and the suffix number.
For further information concerning a serial number, contact your nearest Agilent
Technologies Sales and Service office.

Introduction
Chapter 1 3
Description
The 8480 series power sensors are used for measuring the average power supplied
by an RF or microwave source or device-under-test (DUT). In use, the Power
Sensor is connected to the RF or microwave source and to a compatible power
meter. Suitable and compatible power meters are the EPM series power meters
(E4418B and E4419B), the EPM-P series power meters (E4416A and E4417A) and
the E1416A VXI power meter. Discontinued and obsolete power meters that are
compatible with the 8480 series sensors include the E4418A, E4419A, 435B, 436A,
437B, 438A and 70100A MMS power meter.
The 8480 series power sensors place a 50 ohm load on the RF or microwave source,
except the 8483A which has a 75 ohm load. The power meter indicates the power
dissipated in this load in mW or dBm.
The coaxial power sensors in the 8480 series measure power levels from -70 dBm to
+44 dBm (100 pW to 25 W), at frequencies from 100 kHz to 50 GHz. To cover this
wide dynamic power range, both thermocouple and diode power sensing elements
are used. Both types of power sensing elements have a maximum 50 dB dynamic
range. Thermocouple sensors have a square-law region from -30 dBm to +20 dBm,
and with an attenuator can operate up to +44 dBm. There are three model types of
thermocouple sensors in the 8480 series, covering the complete -30 dBm to
+44 dBm range.
• The A-models cover -30 dBm to +20 dBm.
• The H-models cover from -10 dBm to +35 dBm.
• The B-models cover from 0 dBm to +44 dBm.
Diode detectors (D-models) have the best sensitivity, having an operating range
from -70 dBm to -20 dBm.
Calibration factor (CAL FACTOR) data is provided on a label attached to the power
sensor's cover. Maximum uncertainties of the CAL FACTOR data are listed in the
Specifications section in page 11. This calibration factor is used to adjust the power
meter to suit the particular power sensor and frequency being measured.
NOTE For the B-models in the 8480 series, calibration factor data is valid only when the
sensor is used with the supplied attenuator.

Introduction
Chapter 14
Figure 1-2 8480 Series Power Sensor Simplified Block Diagram
Figure 1-2 shows a basic power sensor block diagram for both thermocouple and
diode power sensing elements. From the RF or microwave signal input, both
thermocouple and diode detector mounts generate very low voltages, (on the order
of nV or µV). The dc voltage is proportional to the power from the RF or microwave
source. As the dc voltage is a very low-level, it requires amplification before it can
be transferred to the power meter on the standard cables.
The amplification is provided by an input amplifier assembly that consists of a
balanced chopper (sampling gate) and an AC coupled low-noise amplifier. The dc
voltage is routed on gold wires to the chopper circuit, which converts the low-level
dc voltage to an ac voltage. To do this, the chopper is uses two field effect transistors
(FET's) controlled by a 220 Hz square-wave generated by in the power meter (the
Chop Signal). The result is an ac output signal proportional to the dc input. The ac
signal is then amplified to a relatively high-level ac signal that can be routed to the
power meter by standard cables.
The autozero signal removes residual error voltages when there is no input RF or
microwave power connected to the sensor input, and temperature compensation is
provided by a thermistor located in amplifier feedback path.
Input
Power
Sensing
Element
Thermocouple
or Diode
Balanced Chopper
Thermistor
Cable
AC Signal
Feedback
Chop Signal
Chop Signal
Autozero

Introduction
Chapter 1 5
Dimensions
The physical dimensions of the power sensors differ in the model types. This is due
to the additional attenuation used to obtain the high power performance.
CAUTION Do not disassemble the power sensor. The 8480 series power sensors are static
sensitive and can be easily damaged.
8480 series, B-models information
The 25 W (+44 dBm) power sensor is a calibrated combination of a 30 dB, 25 W
attenuator assembly and a sensor assembly. The attenuator and sensor assemblies
are calibrated as a set and must be used together if specified accuracies are to be
obtained.
This combination is referred to as the power sensor.
Table 1-1 8480 Series Power Sensor Dimensions (including the RF Connector)
8480 series power
sensor models
Dimensions
A-models 8481A, 8482A and 8483A:
38 mm wide, 30 mm high, 105 mm long (1.5 in. x 1.2 in. x 4.1 in)
8485A and 8487A:
38 mm wide, 30 mm high, 95 mm long (1.5 in. x 1.25 in. x 3.75 in.)
B-models 83 mm x 114 mm x 248 mm (approx. 3.25 in. x 4.50 in. x 9.75 in.)
D-models 8481D and 8485D:
38 mm wide, 30 mm high, 102 mm long (1.5 in. x 1.2 in. x 4.02 in)
8487D:
38 mm wide, 30 mm high, 94 mm long (1.5 in. x 1.2 in. x 3.7 in)
H-models 38 mm wide, 30 mm high, 149 mm long (1.5 in. x 1.2 in. x 5.9 in)

Introduction
Chapter 16
CAUTION Removal of the D-ring that is on the sensor assembly WILL VOID THE
WARRANTY. The input connector on the sensor has a D-ring to prevent the sensor
from being connected to a high power source when its attenuator is not attached.
The sensor must only be connected to the power meter for calibration or to the high
power attenuator for RF measurement.
Safety Considerations
The warning that follows is related to possible personal injury.
WARNING The high power attenuator contains a substrate of beryllium oxide. Beryllium
oxide in a powder form is a hazardous material and may be injurious to your
health if inhaled. Do not perform any operation on the beryllium oxide that
might generate dust. Defective attenuator should be returned to Agilent
Technologies for proper disposal.
8480 series, Options
8485A and 8485D option 033
The 8485A and 8485D power sensors with option 033 are calibrated to measure
power levels in the 50 MHz to 33 GHz frequency range. In all other respects, they
are the same as their respective standard power sensor.
Accessories Supplied
Accessories are required to connect various power sensors to the power meter's 50
ohm, Power Reference (1 mW, 50 MHz) output connector (Type-N (f)).

Introduction
Chapter 1 7
8483A 75 ohm sensor
The 8483A sensor is supplied with an adapter, shown in Figure 1-3. This accessory
is a mechanical adapter only, not an impedance transformer, therefore an impedance
mismatch exists that must be taken into consideration when calibrating the power
meter and sensor. The REF CAL FACTOR, on the power sensor label, has been
adjusted for the impedance mismatch. This REF CAL FACTOR, when used to
calibrate any power meter, will allow calibration to 1.000 mW. The CAL FACTOR,
from the data on the sensor label, should be used for any power measurements in a
75 ohm system at 50 MHz.
CAUTION Remove the mechanical adapter from the power sensor before connecting the sensor
to a 75 ohm source.
Figure 1-3 Mechanical Adapter (8483A Only)
D-model 8480 series sensors (8481D, 8485D, 8485D-033 and 8487D)
D-model sensors are supplied with a 11708A 30 dB attenuator. To calibrate a
D-model sensor, the 1 mW 50 MHz Power Reference supplied by the power meter
must be reduced to 1µW. The reference attenuator provides the means to do this.

Introduction
Chapter 18
NOTE The 11708A 30 dB attenuator is intended for use only at the 1 mW, 50 MHz power
reference of the power meter. Its function as a calibration reference may be
compromised if used for other purposes.
26.5 GHz and 33 GHz Frequency operation (8485A, 8485A-033, 8485D and
8485D-033)
8480 series sensors that operate up to 26.5 GHz and 33 GHz are fitted with
APC-3.5mm (m) connectors as standard. To convert the APC-3.5mm (m) connector
for calibration an adapter (APC-3.5 (f) to Type-N (m)) is included with the power
sensors. Figure 1-4 shows the parts included with your power sensor.
NOTE The APC-3.5mm to Type-N adapter is intended for use only at the 1 mW, 50 MHz
power reference of the power meter. Its function as a calibration reference may be
compromised if used for other purposes.
Table 1-2 11708A 30 dB attenuator characteristics
Characteristic Limits Comments
11708A accuracy at
50 MHz, 25 °C
30 ± 0.05 dB Accuracy traceable to National Institute of
Standards and Technology (NIST), with a
temperature coefficient typically 0.003 dB per
°C.
Dimensions Length: 60 mm (2.4 in)
Diameter: 20 mm (0.8 in)

Introduction
Chapter 1 9
Figure 1-4 8485A, 8485A-033, 8485D, 8485D-033 Sensor Accessories
50 GHz Frequency operation (8487A and 8487D)
8480 series sensors that operate up to 50 GHz are fitted with 2.4mm (m) connectors
as standard. To convert the 2.4mm (m) connector for calibration, adapter (2.4mm (f)
to Type-N (m)) is included with the power sensors (shown in Figure 1-5).
NOTE The 2.4mm to Type-N adapter is intended for use only at the 1 mW, 50 MHz power
reference of the power meter. Its function as a calibration reference may be
compromised if used for other purposes.

Introduction
Chapter 110
Figure 1-5 8487A Power Sensor with Adapter
Recommended Calibration Interval
Agilent Technologies recommends a one-year calibration cycle for the 8480 series
power sensors.
Warranty
The 8480 series power sensors described in this manual are warranted and certified
as indicated on the inside cover of this manual. Power sensors are warranted only
when they are operated within their specifications, especially the maximum power
handling capability. Any power sensor returned to Agilent Technologies under
warranty will be examined carefully to determine if the failure was possibly due to
improper use.
Do not open the power sensor. Any attempt to disassemble the power sensor will
void the warranty.