Agilent Technologies 8494G Service manual

Agilent Technologies
8494/95/96G/H Attenuators
Operating and Service
Manual
Agilent Part Number: 08495-90025
Printed in USA
Print Date: August 2004
Supersedes: July 2002

ii 8494/95/96G/H Operating And Service Manual
Notice
The information contained in this document is subject to change without
notice.
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shall not be liable for errors contained herein or for incidental or
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Agilent Technologies, Inc.
1400 Fountaingrove Parkway
Santa Rosa, CA 95403-1799, U.S.A.
© Copyright 2000–2002, 2004 Agilent Technologies, Inc.

8494/95/96G/H Operating And Service Manual iii
What You’ll Find in This Manual…
•Overview, page 1
•Specifications, page 6
•Installation, page 10
•Operating Instructions, page 12
•Replaceable Parts, page 15
•Service, page 16

iv 8494/95/96G/H Operating And Service Manual
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 BY APPLICABLE LAW,
AGILENT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS
OR IMPLIED WITH REGARD TO THIS MANUAL AND ANY
INFORMATION CONTAINED HEREIN, INCLUDING BUT 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.

8494/95/96G/H Operating And Service Manual v
Service and Support
Product maintenance agreements and other customer assistance agreements
are available for Agilent Technologies products. 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.
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 performed or 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.

vi 8494/95/96G/H Operating And Service Manual
Instrument Markings
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.
Before Applying
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.
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.
1SM1-A This text indicates that the instrument is an Industrial Scientific and Medical Group 1
Class A product (CISPER 11, Clause 4).
This ISM device complies with Canadian ICES-001.
Cet appareil ISM est conforme a la norme NMB du Canada.
This symbol indicates that the power line switch is ON.
This symbol indicates that the power line switch is OFF or in STANDBY position.
!

8494/95/96G/H Operating And Service Manual 1
Overview
This manual contains operating instructions for the Agilent 8494G/H,
8495G/H, and 8496G/H attenuators. Included in the manual is information
required to install and test these attenuators.
Specification Instrument specifications are indicated in Specifications, page 6. These
specifications are the performance standards or limits against which the
instruments may be tested.
Instruments Covered by
Manual 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.
An instrument manufactured after the printing of this manual may have a
serial prefix that is not listed above. This unlisted serial prefix indicates that
the instrument is different from those documented in this manual.
Description The 8494G/H, 8495G/H, and 8496G/H are 50-ohm coaxial programmable
step-attenuators. Each attenuator is composed of three or four attenuator
sections connected in cascade. Each section consists of a precision, thin-film
attenuator card, a lossless thru-line, and a ganged pair of solenoid-actuated
slab line transmission lines. The slab lines are flexed by the solenoid
plungers to make contact with either the attenuator card or the thru-line. The
slab line contacts are gold plated leaf springs which ensure long life and
extremely high repeatability.

28494/95/96G/H Operating And Service Manual
Overview
Figure 1 Typical Four Section Attenuator Schematic Diagram
Table 1 and Table 2 on page 3 and Table 3 on page 4 show the typical
switching arrangement to increase the amount of attenuation in an 8494G/H,
8495G/H, or 8496G/H in a linear manner. To ensure specified performance,
it is recommended that the attenuator sections that are shown in the
following tables be used. With the attenuator programmed for 0 dB
attenuation, the resultant attenuation is the insertion loss (residual
attenuation). The 8494G/H has a minimum selectable step of 1 dB, while the
8495G/H and 8496G/H have a minimum selectable step of 10 dB. The
accuracy of the attenuators is within the limits given in Specifications,
page 6.
•The 8494G/H are four-section attenuators with a maximum attenuation
of 11 dB.
•The 8495G/H are three-section attenuators with a maximum attenuation
of 70 dB.
•The 8496G/H are four-section attenuators with a maximum attenuation
of 110 dB.
NOTE
Solenoid (K4) and
associated circuitry
are not available in
models 8495G and
8495H.

8494/95/96G/H Operating And Service Manual 3
Overview
Table 2 8495G/H Attenuator Switching Order
Table 1 8494G/H Attenuator Switching Order
8494G/H
Attenuator Sections
Atten
(dB) 1 1 dB 2 2 dB 3 4 dB 4 4 dB
0
1X
2X
3XX
4X
5X X
6XX
7XXX
8XX
9X XX
10 XXX
11XXXX
8495G/H
Attenuator Sections
Atten
(dB) 1 10 dB 2 20 dB 3 40 dB
0
10 X
20 X
30 X X
40 X
50 X X
60 X X
70XXX

48494/95/96G/H Operating And Service Manual
Overview
Table 3 8496G/H Attenuator Switching Order
Each solenoid requires a drive of 20 to 30 V with a switching current of
approximately 125 mA*at 24 V dc per section. The solenoid switching time
is less than 20 milliseconds including settling time. Once switched, the
solenoid plungers are held in place by permanent magnets and the solenoid
plungers automatically disconnect the selected coil drive and connect the
opposite coil drive (see Figure 1 and Figure 2). This simplifies the coil driver
circuit design and reduces the amount of heat dissipated by the solenoid
coils since the solenoid coils are energized only for the 20 milliseconds
switching time.
8496G/H
Attenuator Sections
Atten
(dB) 1 10 dB 2 20 dB 3 40 dB 4 40 dB
0
10 X
20 X
30 X X
40 X
50 X X
60 X X
70XXX
80 X X
90 X X X
100 X X X
110XXXX
* For serial number prefixes below 1722A, change 125 mA to 110 mA.