Agilent 8495B Operating and Service

Agilent Technologies
8494A/B, 8495A/B, and 8496A/B
Attenuators

Operating and Service
Manual

Agilent Part Number: 08494-90008
Printed in USA
Print Date: April 2002

Supersedes: October 2000

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.

Agilent Technologies assumes no responsibility for the use or reliability of
its software on equipment that is not furnished by Agilent Technologies.

This document contains proprietary information which is protected by
copyright. All rights are reserved. No part of this document may be
photocopied, reproduced, or translated to another language without prior
written consent of Agilent Technologies.

R

ESTRICTED RIGHTS LEGEND

Use, duplication, or disclosure by the U.S. Government is subject to
restrictions as set forth in subparagraph (c)(1)(ii) of the Rights in Technical
Data and Computer Software clause at DFARS 252.227-7013 for DOD
agencies, and subparagraphs (c)(1) and (c)(2) of the Commercial Computer
Software Restricted Rights clause at FAR 52.227-19 for other agencies.

Agilent Technologies, Inc.
1400 Fountaingrove Parkway
Santa Rosa, CA 95403-1799, U.S.A.

© Copyright Agilent Technologies, Inc. 2000, 2002

ii Agilent 8494A/B, 8495A/B, 8496A/B Operating And Service Manual

What You’ll Find in This Manual…

“Instrument Definition” on page 1

•

• “Description” on page 2

• “Specifications” on page 3

• “Installation” on page 6

• “Operating Instructions” on page 7

• “Operator’s Check” on page 8

• “Replaceable Parts” on page 10

• “Service” on page 11

Agilent 8494A/B, 8495A/B, 8496A/B Operating And Service Manual iii

Warranty

Custom systems are warranted by contractual agreement between Agilent
Technologies and the customer.

Certification Agilent Technologies, Inc., certifies that this product met its published

specifications at the time of shipment from the factory. Agilent Technologies
further certifies that its calibration measurements are traceable to the
United States National Institute of Standards and Technology (NIST,
formerly NBS), to the extent allowed by the Institute’s calibration facility,
and to the calibration facilities of other International Standards
Organization members.

Documentation Warranty

THE MATERIAL CONTAINED IN THIS DOCUMENT IS
PROVIDED "AS IS," AND IS SUBJECT TO BEING CHANGED,
WITHOUT NOTICE, IN FUTURE EDITIONS. FURTHER, TO
THE MAXIMUM EXTENT PERMITTED BYAPPLICABLE LAW,
AGILENT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS
OR IMPLIED WITH REGARD TO THIS MANUAL AND ANY
INFORMATIONCONTAINED HEREIN,INCLUDINGBUT NOT
LIMITED TO THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR
PURPOSE. AGILENT SHALL NOT BE LIABLE FOR ERRORS
OR FOR INCIDENTAL OR CONSEQUENTIAL DAMAGES IN
CONNECTION WITH THE FURNISHING, USE, OR
PERFORMANCE OF THIS DOCUMENT OR ANY
INFORMATION CONTAINED HEREIN. SHOULD AGILENT
AND THE USER HAVE A SEPARATE WRITTEN AGREEMENT
WITH WARRANTY TERMS COVERING THE MATERIAL IN
THIS DOCUMENT THAT CONFLICT WITH THESE TERMS,
THE WARRANTY TERMS IN THE SEPARATE AGREEMENT
WILL CONTROL.

Assistance Product maintenance agreements and other customer assistance agreements

are available for Agilent Technologies products.
For assistance, call your local Agilent Technologies Sales and Service Office

(refer to “Service and Support” on page v).

iv Agilent 8494A/B, 8495A/B, 8496A/B Operating And Service Manual

Service and Support

Any adjustment, maintenance, or repair of this product must be performed
by qualified personnel. Contact your customer engineer through your local
Agilent Technologies Service Center. You can find a list of local service
representatives on the Web at:

http://www.agilent.com/find/assist

Click on “Contact Us” and select your country.

If you do not have access to the Internet, one of these centers can direct you
to your nearest Agilent Technologies representative:

United States [phone]
Canada [phone]
Europe (41 22) 780.6111 (Switzerland)

(33 1) 69 82 66 66 (France)
(49 7031) 464-6222 (Germany)
(44 188) 9696622 (Great Britain)

Japan 0120-32-0119
Latin America (11) 7297-3700 (Brazil)
Australia/New

Zealand
Asia-Pacific 080-047-669

1-800-802-540 (Australia)
0800-738-378 (New Zealand)

Agilent 8494A/B, 8495A/B, 8496A/B Operating And Service Manual v

Safety and Regulatory Information

Review this product and related documentation to familiarize yourself with
safety markings and instructions before you operate the instrument. This
product has been designed and tested in accordance with international
standards.

WARNING The WARNING notice denotes a hazard. It calls attention to a procedure,

practice, or the like, that, if not correctly performedor adhered to, could result
in personal injury. Do not proceed beyond a WARNING notice until the
indicated conditions are fully understood and met.

CAUTION The CAUTION notice denotes a hazard. It calls attention to an operating

procedure, practice, or the like, which, if not correctly performed or adhered
to, could result in damage to the product or loss of important data. Do not
proceed beyond a CAUTION notice until the indicated conditions are fully
understood and met.

Instrument Markings

When you see this symbol on your instrument, you should refer to the instrument’s
instruction manual for important information.

!

This symbol indicates hazardous voltages.

The laser radiation symbol is marked on products that have a laser output.

This symbol indicates that the instrument requires alternating current (ac) input.

The CE mark is a registered trademark of the European Community. If it is
accompanied by a year, it indicates the year the design was proven.

The CSA mark is a registered trademark of the Canadian Standards Association.

This ISM devise complies Canadian ICES-001. Cet appariel ISM est confrome a la
norme NMB du Canada.

vi Agilent 8494A/B, 8495A/B, 8496A/B Operating And Service Manual

1SM1-A This text indicates that the instrument is an Industrial Scientific and MedicalGroup 1

Class A product (CISPER 11, Clause 4).
This symbol indicates that the power line switch is ON.

This symbol indicates that the power line switch is OFF or in STANDBY position.

Safety Earth Ground

This is a Safety Class I product (provided with a protective earthing
terminal). An uninterruptible safety earth ground must be provided from the
main power source to the product input wiring terminals, power cord, or
supplied power cord set. Whenever it is likely that the protection has been
impaired, the product must be made inoperative and secured against any
unintended operation.

BeforeApplying Power Verify that the product is configured to match the available main power

source as described in the input power configuration instructions in this
manual. If this product is to be powered by autotransformer, make sure the
common terminal is connected to the neutral (grounded) side of the ac power
supply.

Agilent 8494A/B, 8495A/B, 8496A/B Operating And Service Manual vii

viii Agilent 8494A/B, 8495A/B, 8496A/B Operating And Service Manual

Instrument Definition

This manual contains installation, operation and test information for the
Agilent Technologies 8494A/B, 8495A/B, and 8496A/B step attenuators.

The instruments covered by this manual have a two-part serial number. The
first four digits and letter comprise the serial number prefix. The last five
digits form the sequential suffix that is unique to each instrument. The
contents of this manual apply to instruments with serial prefixes 2544A and
above.

Older instruments, those with serial number prefixes of 2543A and below,
are documented in this manual under “Manual Changes” below.

An instrument manufactured after the printing of this manual may have a
serial prefix that is not listed above. An unlisted serial prefix indicates that
the instrument is different from those documented in this manual. A manual
for an unlisted instrument is supplied with a Manual Change supplement
containing change information that documents the differences.

Manual Changes This section contains information for adapting this manual to older

instruments. If your instrument's serial number prefix is 2543A or lower, you
may document your instrument by following the instructions below. If your
instrument has a serial number prefix higher than is listed in this manual, it
may be documented in a separate manual supplement.

If you have an older instrument, one with a serial number prefix of 2543A or
lower, you must make the following changes to this manual in order for this
manual to apply to your instrument.

• In “Specifications” on page 3, change the attenuation repeatability to

0.03 dB, typical after 1 million cycles.

• In “Specifications” on page 3, change the minimum life to >1 million

steps or switchings per section.

Agilent 8494A/B, 8495A/B, 8496A/B Operating And Service Manual 1

Description

Description

Agilent 8494A/B, 8495A/B, and 8496A/B are 50-ohm coaxial step
attenuators.

For the 8494A/B, the attenuation can be varied in 1 dB steps, or 10 dB steps
for the 8495A/B and 8496A/B. The attenuation shown on the control knob is
the additional attenuation added in the signal path over the insertion loss of
the attenuator in the 0 dB position.

• Agilent 8494A/B instruments are four-section attenuators with a range

of 0 dB to 11 dB in 1 dB steps.

• The 8495A/B is a three-section attenuator with a range of 0 dB to 70 dB

in 10 dB steps.

• The 8496A/B is a four-section attenuator with a range of 0 dB to 110 dB

in 10 dB steps.

The attenuator sections are connected in cascade. Each section consists of a
precision, thin-film attenuator card, a lossless thru-line and a ganged pair of
edge line transmission lines. The edge lines are flexed to make contact with
either the attenuator card or the thru-line. The edge line contacts are
gold-plated leaf springs which ensure long life and high repeatability.
Low-torque cams flex the edge lines. Table 1, “Attenuator Switching Order”

on page 7 shows the switching arrangements.

CAUTION Do not exceed the RF power rating of 1 W average or 100 W peak with a

maximum pulse width of 10
output connector to greater the 7Vdc. If the attenuator must be connected to
a device with a potential greater than 7 Vdc, use a blocking capacitor.

µs. Do not connect an attenuator RF input or

Instrument Options Each instrument is specified with an option number which denotes the

configuration of the input and output connectors.

Option Connector Description

001 Both connectors Type N female
002 Both connectors SMA female

1

003

1. Option 003 is not available with the 8494A, 8495A, and 8496A.

2 Agilent 8494A/B, 8495A/B, 8496A/B Operating And Service Manual

Both connectors APC-7

Specifications

Specifications

Frequency Range

and Attenuation

Product 8494A 8494B 8495A 8495B 8496A 8496B

Frequency Range dc to 4 GHz dc to 18 GHz dc to 4 GHz dc to 18 GHz dc to 4 GHz dc to 18 GHz
Attenuation 0 dB to 11 dB 0 dB to 11 dB 0 dB to 70 dB 0 dB to 70 dB 0 dB to 110 dB 0 dB to 110 dB
Steps 1 dB 1 dB 10 dB 10 dB 10 dB 10 dB

Attenuation Accuracy ( dB): (Referenced from 0 dB)

8494A/B 8495A/B

8496A/B

AttenuationSelection

(dB)

1 10 0.2 0.3 0.7 0.2 0.5 0.6 0.2 0.5 0.6
2 20 0.2 0.3 0.7 0.4 0.7 0.8 0.4 0.7 0.8
3 30 0.3 0.4 0.7 0.5 0.9 1.2 0.5 0.9 1.2
4 40 0.3 0.4 0.7 0.7 1.2 1.6 0.7 1.2 1.6
5 50 0.3 0.5 0.7 0.8 1.5 2.0 0.8 1.5 2.0
6 60 0.3 0.5 0.8 1.0 1.8 2.4 1.0 1.8 2.4
7 70 0.4 0.6 0.8 1.2 2.1 2.8 1.2 2.1 2.8
8 80 0.4 0.6 0.8 - - - 1.3 2.4 3.2

9 90 0.4 0.6 0.8 - - - 1.5 2.7 3.6
10 100 0.4 0.6 0.9 - - - 1.6 3.0 4.0
11 110 0.5 0.7 0.9 - - - 1.8 3.3 4.4

8494A 8494B 8495A 8495B 8496A 8496B

dc–4

GHz

dc–12.4

GHz

12.4–18
GHz

dc–4

GHz

dc–12.4

GHz

12.4–18
GHz

dc–4

GHz

dc–12.4

GHz

12.4–18
GHz

Agilent 8494A/B, 8495A/B, 8496A/B Operating And Service Manual 3

Maximum SWR

Specifications

Instrument Frequency Range (GHz) Maximum SWR

8495A dc to 4 1.35

Maximum Residual

Attenuation

8495B dc to 8

8 to 12.4

12.4 to 18

8494A,
8496A

8494B,
8496B

Instrument Maximum Residual Attenuation

8494A,
8494B

8495A,
8495B

8496A,
8496B

dc to 4 1.5

dc to 8
8 to 12.4

12.4 to 18

0.6 dB + 0.09 dB/GHz

0.4 dB + 0.07 dB/GHz

0.6 d8 + 0.09 dB/GHz

1.35

1.5

1.7

1.5

1.6

1.9

Attenuation Repeatability

RF Power Handling

Capability

0.01 dB typical after 5 million cycles

1 W average, 100 W peak with maximum pulse width of 10 microseconds
(all models)

Minimum Life > 5 million cycles per section

Environment Limits The instrument should be stored in a clean, dry environment. The following

environmental limits apply to storage and shipment, and operation.

Characteristic Storage and Shipping Value Operating Value

Temperature –40 to +75 °C 0 to +55 °C
Humidity < 95% relative < 95% relative
Altitude < 7600 m (25000 ft) < 4600 m (15000 ft)

4 Agilent 8494A/B, 8495A/B, 8496A/B Operating And Service Manual

Physical Characteristics

Specifications

Instrument Dimensions

(depth x width x height)

8494A/B 6.25 in x 2.875 in x 1.6875 in

159 mm x 73 mm x 43 mm

8495A/B 5.125 in x 2.875 in x 1.6875 in

130 mm x 73 mm x 43 mm

8496A/B 6.25 in x 2.875 in x 1.6875 in

159 mm x 73 mm x 43 mm

1. Dimensions are for general information only. If dimensions are required for building special
enclosures, contact your Agilent field engineer.

2. Weight and width of the instrument varies with the option selected due to the type of connectors.

1

Weight

15 oz
425 g

11 oz
312 g

15 oz
425 g

2

Agilent 8494A/B, 8495A/B, 8496A/B Operating And Service Manual 5

Installation

Installation

Initial Inspection Inspect the shipping container for damage. If the shipping container or

cushioning material are damaged, they should be kept until the contents of
the shipment have been checked for completeness and the instrument has
been checked mechanically and electrically. A procedure for checking
electrical performance is provided under “Operator’s Check” on page 8 (see
also “Performance Tests” on page 9).

If the contents of the shipment are incomplete, or if there is mechanical
damage or defect, or if the instrument does not pass the electrical
performance test, notify the nearest Agilent Technologies office. If the
shipping container is damaged, or the cushioning material shows signs of
stress, notify the carrier as well as the Agilent Technologies office. Keep the
shipping materials for the carrier's inspection. The Agilent office will
arrange for repair or replacement without waiting for claim settlement.

NOTE Containers and materials identical to those used in factory packaging are

available through Agilent Technologies offices. If the instrument is being
returned to Agilent for servicing, attach a tag indicating the type of service
required, return address, model number, and full serial number. Also, mark
the container FRAGILE to assure careful handling. In any correspondence,
refer to the instrument by model number and full serial number.

Mating Connectors Mating connectors used with the Option 001 must be type-N male

connectors, which comply with U.S. military standard MIL-C-39012. For
Option 002, male SMA connectors must be used. For Option 003, APC-7
mating connectors must be used.

CAUTION When installing the instrument, make sure that the connectors do not support

weight or bear torque. The preferred procedure is to set up all equipment in
position before connecting the instrument. Either connector may be used as
the input or output connector.

Installing with Base The attenuators may be installed with or without the base. The base is

removed by unscrewing the two fillister head screws from the bottom of the
base. The attenuator may be mounted without the base by inserting two 4-40
screws into the screw holes in the bottom of the attenuator. Removing the
base and mounting the attenuator does not affect the performance of the
attenuator.

6 Agilent 8494A/B, 8495A/B, 8496A/B Operating And Service Manual

Operating Instructions

Operating Instructions

CAUTION Do not apply power greater than 1 W average, or 100 W peak with a

maximum pulse width of 10 microseconds. If these limits are exceeded, the
attenuators may be damaged.

After the instrument is connected, the attenuation may be selected. Turn
counterclockwise to increase attenuation or clockwise to decrease
attenuation. Either connector may be used as the input or output. Table 1
lists the attenuator switching order.

Table 1 Attenuator Switching Order

8494A/B

Attenuator Sections

Atten

(dB)

000
1X 10X 10X
2 X 20X20X
3 XX 30XX 30X X
4X40X40X
5 X X 50X X50X X
6 XX60XX60XX
7XXX 70XXX70XXX
8XX 80XX

9 X X X 90 X X X
10 X X X 100 X X X
11XXXX 110XXXX

1

1 dB22 dB34 dB44 dB

Atten

(dB)110 dB220 dB340 dB

8495A/B

Attenuator Sections

8496A/B

Attenuator Sections

Atten

(dB)110 dB220 dB340 dB440 dB

CAUTION Do not attempt to force the switch between 0 and the highest value position

as there is a stop between these switch positions.

Agilent 8494A/B, 8495A/B, 8496A/B Operating And Service Manual 7

Operator’s Check

Operator’s Check

The operator's check allows the operator to make a quick check of the
instrument prior to use or if a failure is suspected.

Description The attenuator is driven from a 50-ohm signal source at 1 kHz. The output

level from the attenuator is detected by a narrow-bandwidth voltmeter. The
attenuator and detector range switches are stepped together and the
variations in level noted. This verifies that each attenuator section is being
properly switched and checks the low-frequency accuracy of the attenuator.

NOTE The SWR meter used in this check is calibrated for a square-law detector

and therefore the range changes and errors (read in dB) are twice that
indicated by the meter.

Figure 1 Operator Check Setup

Procedure 1. Connect equipment as shown in Figure 1 with the attenuator set to 0 dB.

2. Set the test oscillator to 0.3 Vrms at 1 kHz.

3. Set SWR meter range to 2 dB (expanded) [or for the 8494A/B to 10 dB
(expanded)] and adjust its bandwidth to center of adjustment range. Fine
tune the oscillator frequency to obtain maximum meter indication.

4. Set the attenuator and SWR meter range switch as shown in Table 2 and
verify that SWR meter indicates within limits shown.

8 Agilent 8494A/B, 8495A/B, 8496A/B Operating And Service Manual

Table 2 Attenuation and SWR Settings

Operator’s Check

SWR Meter Range

(dB)

8494A/B 8495A/B

8496A/B

10 2 0 0 0 - - Setto0.0 Set to 0.5 - ­10 6 1 10 10 0.40 1.40 - - 0.60 1.60
10 12 2 20 20 0.90 0.30 - - 1.10 0.70
10 16 3 30 30 1.35 1.25 - - 1.65 1.75

1

10

12 26 5 50 50 0.35 1.10 - - 0.65 1.90
12 32 6 60 60 0.85 0.00 - - 1.15 1.00
12 36

1

12

14 46
14 52
14 56

22 4 40 40 1.85 0.15 - - 2.15 0.85

42

8494A/B 8495A/B 8496A/B 8494A/B 8495A/B

1

1

1

1

1

Attenuation (dB) Meter Indication (dB)

Minimum Actual Maximum

8494A/B 8495A/B

8496A/B

7 70 70 1.30 0.90 - - 1.70 2.10
8 - 80 1.80 –0.15 - - 2.20 1.15

9 - 90 0.30 0.75 - - 0.70 2.25
10 - 100 0.80 –0.30 - - 1.20 1.30
11 - 110 1.75 0.60 - - 1.75 2.40

8496A/B

8494A/B 8495A/B

8496A/B

1. Adjust range by 2 dB, if needed, to obtain a on-scale indication.

Performance Tests Theinstrument can be tested to the accuracy of the “Specifications” on page

3, with an automatic network analyzer or equivalent equipment of suitable

accuracy. If an automatic network analyzer is available, test the instrument
using the procedures in the analyzer's operating manual.

NOTE The attenuators have no internal adjustments and should not be opened. If

defective, return the attenuator to the nearest Agilent Technologies office for
repair.

Agilent 8494A/B, 8495A/B, 8496A/B Operating And Service Manual 9

Replaceable Parts

Replaceable Parts

Table 3 lists the replaceable parts which are the only parts that can be

replaced without access to the interior of the instrument. If any parts not
listed below need replacement, return the instrument to Agilent
Technologies.

CAUTION Due to special fixtures necessary for assembly, do not attempt to replace any

parts not listed in the table below. If the instrument is opened, the warranty is
void.

Table 3 Replaceable Parts

Description Part Number

Knob 0370-1091
Option 003 APC-7 center conductor contact 1250-0907
Option 003 APC-7 connector outer shell assembly 1250-0909
Option 001 Type N female connector outer shell 1250-0914
Screws for both bases: 4-40 x 7/8 in. Fillister head 2220-0006
Label 0-110 dB for 8496A and B 7120-0543
Label 0-70 dB for 8495A and B 7120-3376
Label 0-11 dB for 8494A and B 7120-4525
Base for 8495A & B 5041-3887
Base for 8494A and B and 8496A and B 5041-3888

NOTE Option 002 (SMA) connectors are not replaceable without access to the

interior of the instrument. If these connectors are damaged, return the
instrument to Agilent Technologies.

10 Agilent 8494A/B, 8495A/B, 8496A/B Operating And Service Manual

Service

Service

Troubleshooting Troubleshootingconsists of performing the “Operator’s Check” on page 8.If

the instrument does not perform within limits, return the instrument to
Agilent Technologies.

Repair The only recommended field repair is replacing the outer connector shell for

the Option 001 and 003, or replacing the center contact in the 7 mm
connector. For any other repair, return the entire instrument to Agilent
Technologies.

Replacing the 7 mm Connector Center Conductor Contact

Through wear or damage, the contact in the 7 mm center conductor may
need replacement. This contact is a small four-pronged contact which snaps
into a recess in the center conductor. With a magnifying glass, examine the
contact for the necessary outward spring action by carefully pushing it in.

CAUTION Do not remove this contact for inspection. It may be damaged by removal.

The prongs of the contact should be free from burrs or wear. If the contact is
removed, do not reuse it. Order contact as Amphenol part number 131-129
or Agilent part number 1250-0907.

If this contact needs replacement, proceed as follows:

1. Place the instrument so the connector faces down.

2. Tap the connector lightly. The contact should now protrude slightly.
Insert the centering pin of the contact extractor,p/n 5060-0370, with the
jaws open.

3. Allow the jaws of the tool used to close and pull straight back from the
connector without twisting.

4. Snap in a new contact by pushing it in place. Test the action of the new
contact by pushing it in. It should spring out again when released.

*

* Amphenol RF Division, Danbury, CT.

Agilent 8494A/B, 8495A/B, 8496A/B Operating And Service Manual 11

Service

Replacing the Connector Outer Shell

NOTE The connector outer shell can be replaced only on the Option 001 (type-N

female) or the Option 003 (7 mm). The outer shell on the Option 002 (SMA)
cannot be replaced in the field.

The connector outer shells on the Option 001 and 003 may be replaced as
follows:

1. With a 9/16-inch (1/2-inch for 7 mm) thin open-end wrench, unscrew
the outer connector body.

2. Replace the connector outer shell. See Table 3 on page 10 for
replaceable parts numbers.

3. Tighten the connector with the same wrench called out in step 1.

12 Agilent 8494A/B, 8495A/B, 8496A/B Operating And Service Manual