HP 82H User's manual

HP 82H User's manual
HP 8481H/82H
Power Sensor
Operating ——
and 1
Manual
NOTICE
The information contained in this document is subject to change without notice.
HEWLETT-PACKARD MAKES NO WARRANTY OF ANY KIND WITH REGARD TO
THIS MANUAL, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. Hewlett-Packard
shall not be liable for errors contained herein or direct, indirect, special, incidental or
consequencial damages in connection with the furnishing, performance, or use of this material.
WARRANTY
À copy of the specific warranty terms applicable to your Hewlett-Packard product and
replacement parts can be obtained from your local Sales and Service Office.
Herstellerbescheinigung
Hiermit wird bescheinigt, daß dieses Gerat/System in Übereinstimmung mit den Bestimmungen
von Postverfügung 1046/84 funkentstört ist.
Der Deutschen Bundespost wurde das Inverkehrbringen dieses Gerätes/System angezeigt und die
Berechtigung zur Überprüfung der Serie auf Einhaltung der Bestimmungen eingeräumt.
Zusatzinformation für Meß- und Testgeräte:
Werden Meß- und Testgeräte mit ungeschirmten Kabeln und/oder in offenen Meßaufbauten
verwendet so ist vom Betreiber sicherzustellen, daßdie Funkentstörbedingungen unter
Betriebsbedingungen an seiner Grundstücksgrenze eingehalten werden.
Manufacturer’s Declaration
This is to certify that this equipment is in accordance with the Radio Interference Requirements
of Directive FTZ 1046/1984. The German Bundespost was notified that this equipment was put
into circulation, and has been granted the right to check the equipment type for compliance with
these requirements.
Note: If test and measurement equipment is operated with unshielded cables and/or used for
measurements in open setups, the user must ensure that under these operating conditions, the
radio frequency interference limits are me at the border of his premises.
HP 8481H/82H
General Information
Instruments Covered by
Manual
Description
General Information
This Operating and Service Manual contains information about
initial inspection, performance tests, adinstments, operation,
troubleshooting and repair of the HP Model 8481H and 8482H Power
Sensors,
This instrument has a two-part serial number. The first four digits
and the letter comprise the serial number prefix. The last five digits
form a sequential suffix which is unique to each instrument. The
contents of this manual apply directly to instruments having the
serial number prefix 2703A and 2704A.
If your instrument has a serial number prefix less than 2703A or
2704 A additional information is located in the “Backdating” section
at the end of this manual. If your instrument has a serial number
prefix greater than 2703A or 2704A look for a vellow “Manual
Changes” supplement that documents the difference.
In addition to change information, the supplement may contain
information for correcting errors in the manual. The supplement
is keyed fo the manual print date and part number, both of which
appear on the front cover,
For information concerning a serial number prefix not listed here, in
“Backdating” or in the “Manual Changes” supplement, contact your
nearest Hewlett-Packard office.
The Power Sensors are used for measuring the average power
supplied by an RF source to a 50-ohm load. In use, the Power Sensor
is connected to the RF source and to a compatible power meter.
(Suitable meters are the HP 435A or 436A Power Meter.) The Power
Sensor places a 50-ohm load on the RF source, and the power meter
indicates the power dissipated in this load. The power is determined
from the RF voltage developed across the Power Sensor load, and is
expressed in pW (or W) and dBm. The HP 436A Power Meter can
also provide readings, in dB, relative to a previous RF input to the
Power Sensor.
The Power Sensors measure power levels from —10 dBm to +35 dBm
(10 uW to 3W), at frequencies from 10 MHz to 18 GHz (HP 8481H)
or 100 kHz to 4.2 GHz (HP 8482H).
The physical configuration of both sensors is the same. However,
because of the different frequency ranges covered, there are some
changes in page numbers and component values.
General Information
HP 8481H/82H
Calibration data is provided by a table on the Power Sensor.
The table, individually prepared for each Power Sensor, shows
the calibration factor (CAL FACTOR) at 17 frequencies. This
calibration factor is used to adjust the power meter to suit the
particular Power Sensor and RF frequency. For meter accuracy, a
table showing the calibration factor to three significant digits is
supplied with each Power Sensor.
Specifications for the Power Sensor are provided in table 1.
Recommended Test Equipment
Table 2 lists the test equipment recommended to check, adjust, and
troubleshoot the Power Sensor. If substitute equipment is used, it
must meet or exceed the critical specifications.
HP 8481H/82H
General Information
Table 1. Specifications
Sensor
5-7/8)
Maximum Permissible RF Power, Average: 3.5W
Maximum Permissible RF Power, Peak: 100W
Maximum Energy Pulse: 100 W/us
HP 8481H
1.20 (0.091) 10 MHz to 8 GHz
1.25 (0.112) 8 to 12.4 GHz
1.30 (0.130) 12.4 to 18 GHz
Weight: Net, 0.2 kg (8 ог)
Frequency Range: 10 MHz to 18 GHz (HP 8481H) and 100 kHz to 4.2 GHz (HP 8482H)
Power Measurement Range: 30 uW to 3W
Maximum SWR (Reflection Coefficient) of Power Sensor:
HP 8482H
1.20 (0.091) 100 kHz to 4.2 GHz
Power Linearity:+5% for CW from 300 mW to 3W!
RF Impedance: 508 nominal
RF Connector: Type N Male (meets military specifications)
Calibration: Individual calibration graph and table, traceable to NBS, provided with each Power
Dimensions, Including RF Connector:30 mm wide, 38 mm high, 149 mm long {1-3/16 x 1-1/2 x
*Negligible deviation below 300 mW.
Table 2. Recommended Test Equipment
Instrument Critical Suggested Use*
Type Specifications Model
Power Meter No substitute HP435B A
Digital Voltmeter Input Impedance: 10 MO HP 3478A TA
Resolution: 4-digit
Accuracy: 0.05% + 1 digit
Oscilloscope; Bandwidth: de to 50 MHz HP 54200A AT
Vertical Sensitivity: 0.2 V/div
Horizontal Sensitivity: 1 ms/div
10:1 Divider Probe 110 MO HP 10004D A
10 pF
Ohmmeter Range: 19 to 100 kQ НР 3478A T
Accuracy: +5%
de Power Supply Range: 0-20 Vde HP 62048 T
Load Regulation: 0.01% + 4 mV
*A = Adjustment, T = Troubleshooting
Installation
HP 8481H/82H
Installation
Initial Inspection
Interconnections
Inspect the shipping container. H the container or packing material is
damaged it should be kept until the contents of the shipment have
been checked mechanically and electrically. If there is mechanical
damage or if the instrument does not pass the perfornnance tests,
notify the nearest Hewlett-Packard office. Keep the damaged
shipping materials (if any) for inspection by the carrier and a
Hewlett-Packard representative.
Storage and Shipment
Environment. The instrument should be stored in a clean, dry
environment. The following limitations apply to both storage and
shipment:
Temperature —40 to +75%C
Relative humidity < 95%
Altitude < 7,600 metres (25,000 feet).
Original Packaging. Containers and materials identical to those
used in factory packaging are available through Hewlett-Packard
offices. If the instrument is being returned to Hewlett-Packard for
servicing, attach a tag indicating the type of service required, return
address, model number, and serial number. Also, mark the container
FRAGILE to ensure careful handling. In any Correspondence, refer
to the instrument by model number and serial number.
Refer to the power meter operating and service manual for
interconnecting instructions.
HP 8481H/82H
Operation
SRST A AR
Operation
Environment
Cautions y
The operating environment for the Power Sensor should be as
follows:
Temperature 0° to 55°C
Relative humidity < 95%
Altitude < 4,572 metres (15,000 feet).
Operating Precautions
Before the Power Sensor is connected, the following precautions must
be observed.
BEFORE CONNECTING THE POWER SENSOR TO ANOTHER
INSTRUMENT, ensure that the instrument and power meter are
connected to the protective earth ground.
Exceeding the energy and power levels shown in Table 1 may result
in damage to the power meter system.
To avoid internal damage to the Power Sensor, connect or disconnect
by turning the Type N RF connector only. Do not turn the Power
Sensor’s plastic body.
The absolute maximum RF signal level that may be coupled to the
Power Sensor is:
Maximum Average Power 3.5W
Maximum Peak Power 100W
Maximum Energy Per Pulse 100W / us.
Power Meter Calibrations
The procedure for calibrating one power meter may be different for
another power meter. Follow the calibration directions given in vour
power meter manual.
Operation
HP 8481H/82H
Tabie 3. HP 8481H/82H Calibration Factor
Uncertainty at 1 W
HP 8481H (RSS) Probable HP 8482H {RSS) Probable
Frequency(GHz) | Uncertainty (%) | Frequency(MHz) | Uncertainty (%)
1.0 GHz 1.9% 0.1 MHz 1.6%
2.0 GHz 1.7 0.3 MHz 1.6
4.0 GHz 1.8 1.0 MHz 1.6
6.0 GHz 1.8 3.0 MHz 1.6
8.0 GHz 2.0 10.0 MHz 1.6
10.0 GHz 2.2 30.0 MHz 1.7
12.0 GHz 2.4 50.0 MHz 0 (ref)
14.0 GHz 2.8 100.0 MHz 1.9
16.0 GHz 3.0 300.0 MHz 1.9
18.0 GHz 3.1 1000.0 MHz 1.7
2000.0 MHz 1.7
4000.0 MHz 1.8
Power Measuremenis
lo correct for varving responses at different frequencies a cal factor
chart is included on the Power Sensors. To use the cal factor at
the frequency of interest, adjust the power meter's CAL FACTOR
control according to the instructions in your power meter's operating
manual.
SWR (Reflection Coefficient) Performance Test
The maximum SWR and reflection coefficient or the Power Sensor
are listed in Table 4. For making these measurements, use equipment
which has measurement uncertainties not exceeding those shown in
the table.
HP 8481H/82H Operation
Table 4. SWR and Reflection Coefficient
Frequency Measuring System Actual Maximum SWR
Reflection Coefficient . Measurement (Reflection Coefficient)
Uncertainty
HP 8481H
10 MHz to 8 GHz 40.025 — 1.20 (0.91)
8 GHz to 12.4 GHz 0.030 | eee 1.25 (0.112)
12.4 GHz to 18 GHz 0.035 — 1.30 (0.130)
HP 8482H
100 kHz to 4.2 GHz -+0.025 ee ne 1.20 (0.91)
Adjustments HP 8481H/82H
Adjustments
FET Balance
Adjustment
Warning R The following procedure exposes high voltage areas within the
power meter, Use extreme care while working around these areas or
personal injury could occur.
Equipment
Oscilloscope HP 54200A
Power Meter HP 435B
Multimeter HP 3478A
The sampling gate balance is affected by the relative positions of
the wires in the Power Sensors, which connect to pins G and H of
connector J1. One wire is black and white; and the other is brown
and white. Moving the black and white wire will adjust the switching
transient amplitude (spike). Moving the brown and white will change
the offset. Once positioned, care must be used not to displace these
wires. To correctly position these wires, after replacement of A2U1,
or if the wires have been moved so as to affect the sampling gate
balance, perform the following procedure:
| If the Power Sensor printed circuit board A? has been removed for
5 repalr, make sure all surfaces are thoroughly clean and free of flux
residues before attempting the following adjustments.
Note
1. Set the multimeter controls as follows:
FUNCTION Voltage
RANGE 20 mV, full scale
2. Set oscilloscope controls as follows:
SENSITIVITY 0.2 V/DIV
SWEEP 1 ms/DIV
TRIGGER INT
Display A
3. Set the Power Meter CAL FACTOR to 100%. Set the Power
Meter RANGE to 1 mW (0 dBm).
4. Open the Power Sensor (see “Disassembly Procedure”, steps
1 through 3). Zero and calibrate the Power Meter. Leave the
opened Power Sensor connected to the Power Meter POWER
REF output. Heat can affect the adjustments so handle the
sensor as little as possible.
5. Turn OFF the POWER REF switch on the rear panel of the
Power Meter.
G. Remove the HP 435B bottom panel. This will expose the circuit
side of the A5 printed circuit board. On A5 you will see a long
double row of soldered terminals numbered 1 to 44.
HP 8481H/82H
11.
Adjustments
. Connect a probe from pin 40 (the number “902” is printed on the
board next to pin 40) to the multimeter input.
. Lay the HP 435B on its left side and remove the right panel.
This will expose th A4 assembly.
. Connect a 1:1 probe from TP4 to channel A on the oscilloscope.
. Ofiset. Read the multimeter and adjust the position of the brown
and white wire until the reading is between —7.0 mV and —2.0
mV. Helpful hint: the relative position of the brown and white
wire to C4 will adjust the offset.
Switching transients. Read the oscilloscope and adjust the
position of the black and white wire until the switching transients
are less than 0.8V peak to peak. Helpful hint: the relative
position of the black and white wire to the collector of Q1 will
adjust the switching transients.
You will find that positioning the wire for switching transients affects
the offset. Go back and forth between the two wires, positioning and
repositioning, until both adjustments are within specifications.
Replaceable Parts | HP 8481H/82H
Replaceable Parts Table 5 is a list of replaceable parts. Figure 1 and Figure 2 illustrate
the major parts. To order a part, quote the Hewlett-Packard part
number and check digit (CD), specify the quantity required, and
address the order to the nearest Hewlett-Packard office. To order
a part not listed in table 4, give the instrument model number,
instrument serial number, the description and function of the part,
and the quantity of parts required.
Note A Within the USA, it is better to order directly from the HP Parts
3 Center in Roseville, California. Ask your nearest HP office for
information and forms for the “Direct Mail Order System”. Also
your nearest HP office can supply toll free telephone numbers for
ordering parts and supplies. A list of HP Sales and Service Offices is
printed inside the cover of this manual.
10
HP 8481H/82H Service
Service
Test equipment which meets or exceeds the critical specifications in
table 2 may be used in place of the recommended instruments for
troubleshooting the Power Sensor.
Figure 1 and Figure 2 show the locations of the assemblies and
components. Figure 3 is the schematic diagram.
TT MPO
NOTE:
MP11-18 NOT SHOWN
SAME AS MP0.
MP26-22 NOT SHOWN
SAME AS MP19,
Figure 1, lilustrated Parts Breakdown
11
Service
HP 8481H/82H
TOP VIEW
TE
A tas
=
Er
AT BULKHEAD
ASSEMBLY
Pr al le ale al ale a al ae al als
a a on
CAUTION |
PTA
Ni ii Na aly iyi Wa uy
DO NOT DISASSEMBLE
A1 BULK HEAD ASSEMBLY
a a ый
AZ INPUT
» AMPLIFIER
ASSEMBLY
BOTTOM VIEW
(A2A2 Input Amplifier Assembly)
pay harina
ERRONEA
Er,
sr
Ts
oe Ti
mime НЫ,
Figure 2. Component and Assembly Locations
12
Service
HP 8481H/82H
DIT L3034 GHL KHOI7G AILNGNVHHId AYVH
TOYS IVY LON
(L1009-T8P80 !HTSP8) (06009-18480 HI8P8) A TENISSY HALIIIdAY J
ANI TV
SIHL “IP 40 SA19YLd32JH Nid 3HL OND SQDHd .
1931 M213AYIO-304v1 30404 10N DO “NOLIAVD SI AG6WMISSV OV:EbIN0 IV CE
in a GE SI they
+ 8.8 GE tm 298 SI IHZVY 14288
1 4+ SI 1902Y
e 5 о % , a. BM 494 SI TUZY IHIBHB
23 SHOTS SY J4VY 106% ОМУ
21 O O la Tes IM INZY HÜLSISEH 40 S301VA FHL 2
PO O/ 6 Di 10 ir ‘SOYHY{/GHOIH Ni Z9NVLIOVdYS
. *SAHO NI SOMNVLSISCE
MZA JO ad X1434d ON SO3LVOIONI USIMHIMLO 853M ‘1
3015 ONIIVR in SNOIIVNDISZO IONIHIIN sION
ee A eee _ EP VOSEZ :HZ8+B_!V6+ÈZ HiB58 ¥OSNIS us
[ A008 ци LE |
HO 1 0TNNGD ua
ANNOBO ‹ азов f |
WNBIS | zay a” i
guna devo | |
SHO LOINNDD
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| | a
aNNOHS TT | 5 PC AFANI
SiSSVHO N Si < || EA + pt
< PIB. EMS iZ BLOM == 4 E
HOLS ISI e sa" Ir 10 lier @
iNNOR в | | |
NEAL TY f ; | Ame te Ÿ
37852 30001
HOSNIS MINOS HIVE IIS E 6087 |
VIA € | >= HIM |
HALIW H3KOd de UN neo , 0708
Qi 1 JL € - ST т (+) F
me pi "La 10 1 ) I ¥ i
97 I 4
LD toi
IH 22 indino dodo pel <
OV OI THYS wl ён. ZE ALON ha 90D OWE EH) md
. 5 218
| ин 1 AT TANT LAN es
B)>i——( as 8-0 8 + (2160-5181) = --
eH pee HO TE 4-е ” В CP IB79-18P972 :HI0+9?
1 ASMESSY OY3HX750g Y
GH3Z Ginv TI ——(Z86)+-e
` En г wn 71: VS ON ау С ой |
HeB¥E/H18¥8 SHOSNIS HIM
Od
Figure 3. Schematic Diagram
13
Service
Table 5. Replaceable Parts
HP 8481H/82H
Reference HP Part iC à: Mir
. . Descriptio ar
Designation | Number D| “Y ption Code Mir Part Number
A1 08421-60014 | 5 1 20 DE BULKHEAD TYPE N 28480 08481-80014
{FOR 8481H ONLY)
РЕ 08482-600091 9 1 20 DB BULKHEAD TYPE N 28480 08482-60009
(FOR 84824 ONLY)
AZ 08481-60040 | € 1 BOARD ASSEMBLY. POWER SENSOR 28480 08481-60040
: (FOR 8481H ONLY} |
A2 08482-60017 | $ 1 BOARD ASSEMBLY, POWER SENSOR 28480 08482-60017
{FOR 8462K ONLY)
A2C1 0180-2515 2 2 CAP-FXD 47UF 6 Y TA 12344 | TISSFA7EMOOGAS
(FOR 8481H)
A2C1 0180-2781 0 1 CAP-FXO SOUF 10 Ÿ TA 12344 | T3556296K010AS
(FOR 8482H)
AZCZ 0160-5947 7 4 CAP-EXD 1000PF SOV
A263 0160-5947 9 CAP-FXD 1000PE 50V
A2C4 0180-09594 À © 1 CAP-FXD 3.3UF 19 Y TA 12344 | T350A335MD16AS
A205 0189-3084 | € 1 CAP-EXD O.1UF 100 V 06382 | FD22XSRZA104K
A2C8 0160-3879 7 1 CARP-FXD 0.01UF 100 Y 09989 | RPET21-105X7R102MIDOY
A2C7 0160-5947 . | 7 CAP-FXD 1060PF 50V
A2CS 0160-5947 7 CAP-FXD 1000PF 50V
A2CS 0180-2515 | 8 CAP-FXD 47UF 6 у ТА 12344 | TI555A76M0OSAS
A2C18 0180-2545 | 4 1 CAP-FXD TOQUF 4 V TA 01765 | 202L6301-107-6-552
A201 1854-0610 6 1 TRANSISTOR NPN SI T0O-46 FT-B00MHZ 28480 1854-0610
ATR 0698-3260 | 9 1 | RESISTOR 464K +-1% ‚1258 ТЕ TC=0+-100 12498 | CTA
{FOR 8481H ONLY)
AZRY 0757-0483 8 1 RESISTOR 562К +-1% ‚1258 TF TC=0+-100 19701 5033R
(FOR 84972H ONLY}
A2R2 0698-7248 1 1 RESISTOR 3.18K +-1% .OSk TE TC:0+-190 12498 |! C3-1/8-T0-2161-F
A2R3 0898-7224 | 3 1 RESISTOR 318 +-1% .0SW TF TCr0+~100 12488 | £3-1/8-TO-316R-F
AZRA 0698-7236 7 1 RESISTOR 1K +-1% 054 TF TCs0+-100 12498 | €3-1/8-T0-1001-F
AZRT1 | 0811-3210 1 1 RESISTOR 31.8 +-5% ‚0б%Ы PN TC:+5040+-250 91686 | R342
А2Ы! 1813-0912 8 4 IC MISC TO-8 PKG 28480 1813-0912
A2 MISCELLANEOUS
0590-1040 1 1 THREADED INSERT-NUT 0-80 .06-IN-Le SST 46384 | YC3-1505
5040-8938 16 1 SPACER 28480 5049-6938
CHASSIS PARTS
31 08481-80024] 7 1 CONNECTOR, 12-PIN FEMALE MULTICONTACT 28480 | 08481-60024
MP1 5040-6998 9 2 SHELL, PLASTIC 28480 5040-6998
Mp2 5040-6998 9 SHELL, PLASTIC 28480 3040-6998
MP3 08481-20011 | 8 2 CHASSIS 28480 | 08481-20011
MP4 08481-20011 | € CHASSIS 28480 | 08481-20011
HPS 08481-20008 3 1 END BELL 28480 08481-20008
MAS 1450-1978 10 4 SPRING-CPRSN .088-IN-0D .186-IN-DA-LG 84830 C1-0128-2-55
MP7 1251-3383 18 4 NUT- AUDIO CONN 05878 | 91-T-1335-6-9
MPS 08481 -00002 1 5 2 SHIELD 28480 08481-00002
MPS 58481-00002 ! S SHIELD 28480 08481-00002
МР10-
МР1& 3030-0854 1 g SCREW-SKT MD CAP 0-80 ,188-IN-La 551-304 | 00000 ORDER BY DESCRIPTION
MP; S- :
MP2 2 3030-0422 | 8 4 SCREI-SKT HKD CAP 0-80 .188-IN-LG SST-302 | 00000 ORDER BY DESCRIPTION
MP23 2030-0436 14 1 SCREW-SKT HD CAP 0-80 .5-IN-LG 551-300 00000 ORDER BY DESCRIPTION
MP24 8040-8839 | 7 1 CLAMP 28480 5040-8938
MP25 6040-6940 g 1 BLOCK 28480 5040-6940
MP26-MP27 NOT USED
MP] 68482-80001 | 3 1 i LABEL-ID (FOR 8482H ONLY)
MP3? 08486-80001 LABEL-CAL FACTOR (BLANK) (8431H AND 8482H)
MP33 08486-80005 LABEL-INFO (SIDE)
M P34 7121-2422 LABEL-WARNING (SIDE)
MP35 00435-60030 KNOB ASSEMBLY (OPTION 092 ONLY)
MP36 8710-0055 WRENCH-SPLINE (OPTION 602 ONLY)
MPa37 0460-1151 TAPE IND. (OPTION 002 ONLY)
Ri 0898-7249 RESISTOR 3.48K +-1% 054 TF TC=0+-100 12498 | C2-1/8-10-3481-F
14
HP 8481H/82H Service
Table 6. Code list of Manufacturers
Mir Zin Cod
Manufacturer Name Address ip Code
Code
00000 ANY SATISFACTORY SUPPLIER
00843 HOFFMAN ENG CC DIV OF FED CARTRIDGE | ANOKA MN 55303
01886 REL ELECTRONICS INC NOR THEROOK IL us 60062
01766 INTL, CRYSTAL MFG СО ТЫС OKLAHOMA CITY OK #3102
05876 US POLYMERIC INC STANFORD CT 06804
06383 PANDUIT CORP TINLEY PARK IL US 60477
09969 DALE ELECTRONICS INC YANKTON SD US 57078
12344 TALL Y CORP KENT МА Q80 31
12498 CRYSTALONICS, DIV TELEDYNE CAMBRIDGE MA 62140
19701 MEPCO/CENTRALAB INC | RIVIERA FL US 33404
25480 MEULETT-PACKARD CO CORPORATE HO PALO ALTO CA 94304
48384 PENN ENGINEERING & MFG CORP DOYLESTOUN PA US 18901
84830 LEE SPRING CO BROOKLYN NY US 11219
Principles of Operation
Bulkhead assembly Al presents a 50-ohm load to the RF signal
applied to the power sensor. The RF signal absorbed by the
thermocouples generates a dc voltage that is proportional to the RF
input power.
Components A2E1 and A2E2 are ferrite beads situated in the black
plastic block through which the wires from Al pass to A2. Each
ferrite bead increases the self-inductance of the wire passing through
the bead, causing this portion of wire to act as an RF choke. The
result is to minimize RI" feedthrough to the A2 input amplifier
assembly. | |
The dc output from the bulkhead assembly is applied to the two
field-effect transistors (FET’s) in A2U1. These transistors function as
a sampling gate (or chopper). The sampling rate is controlled by a
220 Hz square wave supplied by the power meter. The sampling gate
output (at pin 3 of A2UI) is a 220 Hz square wave having a voltage
proportional to the RF power input.
The output of A2U1 is amplified about 700 times by an operational
amplifier made up of A2Q1 and the first amplifier stage in the power
meter. Figure 4 is a simplified diagram of the complete operational
amplifier.
15
Service
HP 8481H/82H
JANN POWER SENSOR EON RRL POWER METER PE лоно
|
|
!
16
¡+12 VDE
SAMPLED AC + |
INPUT 220 Hz | DP
C8 | an
Юр | $ + De
_ O | 1 | OUTPUT
Ql | |
i |
18 m
SHAPING | €
- | NETWORK % 22. 1K
RTi |
(OLY “| —
1000
Av ww——-12 VDC
POWER SENSOR CABLE
Figure 4. Operational Amplifier
The Auto Zero Feedback circuit is conpled to the Power Sensor from
the Power Meter. The de voltage used to set the zero level is applied
to the input of FET A2U1Q1 by using A2R1 and the series resistance
of the thermocouple A1TCI as a voltage divider.
When the Power Sensor is used with the HP 436A Power Meter,
the resistance of R1 indicates the type of power sensor in use. As a
result, the power meter automatically selects the proper measurement
range. The 3.48K ohm resistance of R1 causes selection of the —15
to +35 dBm range. With the HP 435A Power Meter, R1 serves no
function.
Troubleshooting ‘The troubleshooting information which follows 15 intended to isolate
Caution U
a problem to a stage. The defective component can then be identified
by voltage and resistance checks. The field-effect transistors (FETs)
in A2U1 are slightly light sensitive. As a result, de levels are shifted
slightly when the FETs are exposed.
Be extremely careful when measuring accross the gold wires. They
are delicate and can be damaged easily.
The Al bulkhead assembly normally supplies +3.79 £1 mV when
the RF input is 3W. Measure this voltage at A2U1 pin 1. This de
voitage will vary somewhat if the A2 input amplifier is inoperative,
or if the bulkhead assembly is disconnected from the input amplifier,
HP 8481H/82H
Repair
Service
Resistance measured across the two gold wires leading to the A2
assembly should be 200 +10 ohms (HP 8481H) or 245 12.5 ohms
(HP 8482H). Note that excessive power will damage either the 20
dB pad or the thermocouples. If the 20 dB pad is damaged it will
present an open circuit to the input signal. If the thermocouples are
damaged their resistance will increase. If the Al Bulkhead Assembly
1s defective, the entire Bulkhead Assembly must be replaced.
The FIT7s in A2U1 may be checked by the following procedure:
1. Disconnect the cables from the Power Sensor.
2. Remove the upper chassis from the Power Sensor. (Refer to
“Disassembly Procedures”).
3. Measure the resistance between pins 1 and 2 of the A2U1. The
resistance should be 15 + 0.75 ohms. The same resistance should
be found between pins 8 and 9 of A2U1.
4. Short pins 4, 6, and 9 of A2U1. While the pins are shorted,
measure the resistance between pins 2 and 3, and between pins 3
and 8, of A2U1. The resistance should be less than 40 ohms.
5. Set a power supply to 10 Vde.
6. Connect the positive side of the power source to the Power Sensor
signal ground. Connect the negative power supply lead to pins 4
and 6 of A2U1.
7. Measure the resistance between pins 2 and of A2U1. Also measure
the resistance between pins 3 and 8 of A2U1. In both cases, the
resistance should be several hundred times the resistance found in
step 4.
The 220 Hz drive from the power meter should have the following
levels:
a. —0.05 + 0.05 Vdc (top of square wave).
b. > —8 Vdc (bottom of square wave).
In most cases it may be assumed that the operational amplifier
(made up of A2Q1 and the first amplilier in the power meter) is
operating correctly if the dec voltage on the metal cover of A201
(collector) is —70 + 30 mYde.
Cieanliness
Do not handle the A2 input amplifier circuit board more than
necessary. Dirt or moisture from the hands may make the circuits
inoperative. Keeping in mind its highly flammable nature, a solution
of pure isopropyl or ethyle alcohol can be used to clean printed
circuits and connectors. It is particularly important to keep the area
around A2U1 clean.
17
Service
18
Caution
CAUTIONS y
Caution y
HP 8481H/82H
The RF connector bead inside the Type N connector deteriorates
when contacted by hydrocarbon compounds such as acetone,
trichlorethylene, carbon fetrachloride, benzene, ...
Soldering Techniques
The Power Sensor is a high-sensitivity device, and is affected by very
small differences in temperature between its components. Therefore,
alter the performance of any soldering in the unit, severol hours must
be allowed for the unit to reach thermal equilibrium before it is used
or tested
Capacitors A202, A2C3, A2C7, and A2C8 (figure 2) require
low-temperature soldering techniques. The connections to these
capacitors are a gold film deposited on a ceramic base. Molten solder
results in the gold forming an amalgam with the solder, and the
consequent removal of the gold from its ceramic base. Soldering must
be done quickly, and a low-temperature soldering iron and solder
must be used. The capacitors must be discarded if unsoldered. If
integrated circuit A2U1 or transistor A2Q1 is replaced, two of these
capacitors must be removed, and therefore must be replaced with
new ones.
a. Use a temperature controlled 600°F (311°C) soldering iron with a
Zero crossover tip,
b. Low-temperature solder RMA flux, SN62.
Disassembly Procedures
Disassembly must be performed in the sequence described below,
otherwise damage may be caused to the two gold wires between the
Al bulkhead assembly and the A2 input amplifier assembly. If these
wires are damaged, the Al bulkhead assembly must be returned to
the factory for repair.
Each Power bensor has an individually prepared graph on the
housing. If more than one Power Sensor is disassembled, be sure to
use the proper housing for each when they are reassembled.
Disassemble the Power Sensor by performing the following steps:
The gold wires connecting the Al Bulkhead Assembly and the A2
Input Amplifier Assembly are extreme;ly delicate and may be easily
broken. Be careful when working around them.
1. Insert the blade of a large screwdriver between the two-piece
plastic shell at the rear of the Power Sensor. Gently pry the
sections apart. (See figure 5.)
2. Proceed to the other side of the connector and again pry the cover
sections apart. Remove the shells and magnetic shields.
HP 8481H/82H
Ch On
]
Service
Position the Power Sensor as shown in figure 6 (top). The small
hole 5 should be on the left side of the RF input connector.
Remove the allen cap screws 1, 2, 10, and 13. Loosen 11 and 12.
Remove the upper chassis from the Power Sensor.
Remove the spring clamp cap screw 7 to free the gold leads which
come from the Bulkhead Assembly.
Remove cap screws.
Slide the Bulkhead Assembly straight out from the chassis.
Remove cap screws 8, 9, 11, 12, 14, and 15.
Lift the A2 Input Amplifier and J1 connector out of the chassis.
Figure 5. Removing the Power Sensor’s Cover
19
Service
HP 8481H/82H
ac a ae das ca bk ee oN ale ah ae hae
| CAUTION
E
TP a
EC
DO NOT DISASSEMBLE
"Al BULKHEAD ASSEMBLY
20
Figure 6. Power Sensor Hardware Locations
HP 8481H/82H
Caution y
Service
Reassembiy Procedures
The gold wires connecting the Al Bulkhead Assembly and the А2
Input Amplifier Assembly are extremely delicate and may be easily
broken. Be careful when working around them.
3
. Place the printed circuit board and connector into place.
Cap screws 8, 9, 11. 12, 14, and 15 must be inserted but not
tightened. Refer to figure 6.
. Center the circuit board so there is equal air gap between each
side and the chassis. Tighten 8, 9, 14, and 15.
With small hole 5 to the left, carefully insert the gold leads on
Al bulkhead assembly through the holes in the black plastic
guide on A2 input amplifier.
Insert screw 3, 4, and 6. Tighten only screw 6.
. Position the ends of the gold wires over he pads on A2U1. The
wires should not pass over the hole in the pad. Lightly clamp the
leads in place with screw 7. DO NOT fully compress the spring.
. Place the upper chassis in position and insert cap screws 1, 2, 10,
and 13.
. Tighten 1, 2, 3, and 4.
. Tighten 10, 11, 12, and 13.
10.
Place the plastic shells, magnetic shields, and the chassis together
as shown in figure 1. Snap the plastic shells together.
21
Backdating
HP 8481H/82H
Backdating
How to use this section.
22
This section contains information for adapting this manual to
instruments for which the content does not directly apply.
If the serial prefix of your HP 8481H is 2604A or below, this section
applies to you. If the serial prefix of your HP 8482H is 2609A or
below, this section applies to you. Find the serial prefix that applies
to your instrument and make the changes described below.
2604A, 2609A
1. Replace Figure 2 Component and Assembly Locations with the
Figure 2 in this section.
2349A, 2350A
1. Replace Figure 2 as described above.
2. The appearance of the labels changed. The preferred replacements
are listed in the parts list.
2237A
1. Changes listed above apply to this prefix.
2. Compression spring MP6 and screws MP10 through MP18 were
changed. The preferred replacements are listed in the parts list.
3. In Power Sensors with this prefix number pin A was added to
J1. Pin A was connected to the junctions of F, M and J. When
servicing Power Sensors with this prefix we recommend removing
this connection, isolating pin A.
1925A, 1926A
1. With the exception of the addition of pin A to J1, all the changes
listed above apply to instruments with these prefixes.
2. Four capacitors were added to connector J1. The partial
schematic of Figure 3, showing their placement, is in this section.
When servicing Power Sensors with these prefixes, we recommend
removing these capacitors.
1545A
l. With the exceptions of changes to J1 (J1 is schematically the
same as depicted in this manual) all changes listed above apply to
instruments with this prefix.
2. The part number for J1 was 1251-3228. The part number
currently listed in the parts list is the preferred replacment.
3. The part number for A2 Assembly was 08481-60017 for the HP
8481H, and (8481-60005 for the HP 8482H. The part numbers
currently listed in the parts list is the preferred replacement.
HP 8481H/82H Backdating
TOP VIEW BOTTOM VIEW
o vns (AZA2 Input Amplifier Assembiy)
(ENT ATA
AIRE
SEER
SA
i
i
Sh
er
3
AZ INPUT
p AMPLIFIER
ASSEMBLY
=
Eo
Te
e
EE A
TREE he
Al BULKHEAD
ASSEMBLY
a
CAUTION
E A а щи
DO NOT DISASSEMBLE
AT BULK HEAD ASSEMBLY
25
5
e
e
НЕ
5 a
A
meter
e
UE
== ET
ue
E
Figure 2. Component and Assembly Locations (1545A through 2609A)
23
Backdating
24
Jl CONNECTOR ASSEMBLY
(28481-60024)
pres setter
He
HP 8481H/82H
AUTO ZERO N
Г
+
229 Hz! 1)
GATE DRIVE
SAMPLED AQ
504
an
QUTPUT 228 Hz
ws msi № ON a AN a FA
с
FEEDBACK
RETURN TE PO due TER
> VÍA POWE
MOUNT SENSOR CABLE
RESISTOR
CHASSIS
CF
® NF GROUND
“M
в GUARD
< J CONNECTIONS
SIGNAL
—< Ë GROUND
7 CONNECTOR
BODY
| 7
Figure 1-1. P/O Figure 3. Schematic Diagram (1925A, 1926A)
REGIONAL SALES AND SUPPORT OFFICES
For information relating to Sales or Support of Hewlett-Packard products, first contact your locai
Hewlett-Packard office listed in the white pages of your telephone directory. if none is listed locally,
contact Hewlett-Packard at one of the offices listed below to obtain the address or phone number
of the Sales or Support office nearest you.
The format for telephone numbers is listed as: (country code/area code or city code) local
number. For example, at European Operations HQ, the main site number is listed as:
(41/22)780.8111; 41 is the country code, 22 is the city code, and 780.8111 is the local number.
EUROPEAN
MULTICOUNTRY
(Scandinavia, Middle East,
Africa, Eastern Europe)
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150, route du Nant-d'Avril
P.O. Box 1217 Meyrin
2/Geneva
Switzerland
Tel: (41/22)780.8111
Fax: (41/22)780.8609
FRANCE
Hewiett-Packard France
- Parc d'Activite du Bois Briard
2, avenue du Lac
91040 Evry Ce'dex
France
Tel: (33/1)69 91 80 00
Fax: (33/1)69 91 84 32
GERMANY
.Hewiett-Packard GmbH
Herrenberger Strasse 130
D-7030 Boblingen
West Germany
Tel: (49/7031)14-0
Fax: (49/7031)14-2999
ITALY
Hewlett-Packard Italiana
S.p.A.
Via Giuseppe di Vittorio, 9
20063 Cernusco sui Navigilo,
Milan
italy
Tel: (38/2)921 001
Fax: (39/2)921 044 73
UNITED KINGDOM
Hewiett-Packard Ltd.
Nine Mile Ride
Wokingham, Berkshire RG11
3LL
England
Tel: (44/344)773100
Fax: (44/344)763526
AUSTRALASIA
REGION
Hewlett-Packard Australia Lid.
31-41 Joseph Street
Biackburn, Victoria 3130
Australia
Tel: (61/3)895-2895
Fax: (61/3)898-7831
CANADA
Hewlett-Packard (Canada)
Ltd.
6877 Goreway Drive
Mississauga, Ontario L4V 1M8
Canada
Tei: (1/416)678-9430
Fax: (1/416)678-9421
FAR EAST REGION
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22nd Floor
West Tower, Bond Centre
89 Queensway, Central
Hong Kong
Tel: (852)848-7777
Fax: (852)868-4997
JAPAN
Yokogawa-Hewlett-Packard
Ltd.
3-29-21, Takaido-Higashi
Suginami-Ku, Tokyo 168
— Japan
Tel: (81/3)331-6111
Fax: (81/3)331-6631
LATIN AMERICA
REGION
HP Mexico, S.A. de C.V.
Monte Pelvous No. 111
Fracc. Lomas de Virreyes
11000 Distrito Federal
Mexico
Tel: (52/5)202 01 55
Fax: (52/5)540 42 08
EASTERN U.S.A.
REGION
Hewlett-Packard Company
4 Choke Cherry Road
Rockville, MD 20850, USA
Tel: (1/301)670-4300
Fax: (1/301)670-4531
MIDWEST U.S.A.
REGION
Hewlett-Packard Company
5201 Tollview Drive
Rolling Meadows, iL. 60008,
USA
Tel: (1/708)255-9800
Fax: (1/708)259-4995
SOUTHERN U.S.A.
REGION
Hewiett-Packard Company
2015 South Park Place
Atlanta, GA 30339, USA
Tel: (1/404)955-1500
Fax: (1/404)980-7669
WESTERN U.S.A.
REGION
Hewlett-Packard Company
5161 Lankershim Bivd.
N. Hollywood, CA 91601-
3794,
USA
Tel: (1/818)505-5600
Fax: (1/818)505-5875
OTHER
INTERNATIONAL
AREAS
Hewlett-Packard Company
3495 Deer Creek Road
Palo Alto, CA 94304-1316,
USA
Tel: (1/415)857-5027
Fax: (1/415)857-7045
1990
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