HIGH POWER NETWORK
ANALYZER
HP 8720B-H83
SERIAL NUMBER PREFIX
2909A AND ABOVE
MODIFICATION PART NO. USE THIS MODIFICATION
08720-90112 WITH MANUAL PART NO.
SEPTEMBER 1989 08720-90105
REV. 2PRINTED MAY 1989
HP 8720B-H83
Page 2 of 7
INTRODUCTION:
This manual insert describes the differences in the HP 8720B Option H83 High Power Network
Analyzer compared to the standard HP 8720B. It also describes the manual changes necessary to
document the HP 8720B-H83.
DESCRIPTION:
The HP 8720B Option H83 is a standard HP 8720B that has been modified to
permit higher power at the measurement ports. This is accomplished by inserting a high power
amplifier into the RF signal path through
connectors on the instrument rear panel. The instrument is shipped
from the factory with jumper cables installed on the rear panel connected in what is termed the "BYPASS" configuration (see Figure 2).
This will allow the instrument to be used with normal power levels
over a reduced frequency range. The reference channel (R) has
been brought out to the rear panel to allow the user to set the power
at the test ports as well as to make it possible to define a particular
reference configuration.
The HP 8720B Option H83 differs from the standard HP 8720B in that a
power splitter (with a 6 dB nominal loss) is replaced with a low loss
(<1 dB) directional coupler. Since couplers have limited
frequency response compared to power splitters, the frequency
range of the HP 8720B Option H83 in the "BYPASS" and "HIGH POWER"
configurations is degraded below 2 GHz. The unit operates like
a standard HP 8720B in the "TEST" configuration.
OPERATION:
* * * * * * * * * * * * * * CAUTION * * * * * * * * * * * * * * * *
* A high level RF signal may be present at the test ports on *
* retrace. Caution should be taken in testing active components. *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
The ALC loop in the HP 8720B Option H83 is on during forward sweep
and levels the RF signal at the test ports. However, during retrace
the ALC loop is turned off by internal software and a fixed bias
current is injected into the source modulator. Depending on the
gain of the amplifier being used, a high level RF signal may be
present at the test ports during retrace (See HIGH POWER operation
for amplifier constraints). This is an important consideration
since excessive power can damage sensitive devices. The loss from
RF IN to PORT 1 typically increases from 1 dB at 2 GHz to 6.5 dB at
20 GHz. Also, excessive power will cause error messages to appear
on the analyzer display. These error messages will be of two types:
PHASE LOCK LOST and/or EXCESSIVE POWER AT THE TEST PORTS.
NOTE: The internal software has not been modified for this option
and the power levels indicated on the HP 8720B Option H83
may differ depending on which user configuration is chosen.
HP 8720B-H83
Page 3 of 7
OPERATION (continued):
The power appearing at the measurement channel is dependent on
the reflection coefficient of the load at the test port. During
error correction, with an open and/or a short connected, all power
is reflected and coupled back to the measurement channel through the
nominal 20 dB coupling factor. The overload error messages are designed to be enabled at nominally +3 dBm at the sampler (+23 dBm at
test ports). However, at levels exceeding -10 dBm (+10 dBm at test
ports) the sampler begins to limit. The minimum recommended power
level into REF IN is -20 dBm. Below this level the measurement is degraded due to noise. Additionally, internal service tests 21 and 22
may fail due to the extra cable loss of the HP 8720B Option H83.
The HP 8720B Option H83 can be configured in three different modes
of operation as described below. See Figure 2 for RF diagrams of each configuration.
BYPASS
Connect the supplied semi-rigid RF cables from RF OUT to RF IN and from REF OUT to REF
IN on the rear panel. The test port power
will be as displayed over the frequency range 2 GHz to 20 GHz.
The unit will continue to operate below 2 GHz but the test port
power will increase as frequency decreases. Also, the source may go
unleveled at the low end of the frequency range due to the ALC loop
running out of range. This configuration is not specified below 2 GHz.
HIGH POWER
Insert an external microwave amplifier (HP 8349B Option H83 or
equivalent) into the signal path as shown. Minimum lengths of high quality microwave cable
should be used since external cabling will
affect the power level at the test ports. The maximum recommended input power level that
should be applied to the HP 8720B-H83 is
+23 dBm. The unit can withstand a rear panel RF INPUT level of
+27 dBm without permanent degradation of performance. To provide
+10 dBm of power at the test ports the following external amplifier
considerations are given:
Minimum gain.............20 dB
Maximum gain.............28 dB
Minimum output power....+20 dBm
NOTE: Excessive output power will cause overload at the measured
channels which will generate error messages on the display.
HP 8720B-H83
Page 4 of 7
OPERATION (continued):
TEST
The HP 8720B Option H83 operates like a standard HP 8720B in
this configuration except for the additional cable loss in the
source path. Tests which require equal time delay between R and A
or R and B inputs without error correction will require extra delay
to be added into the reference path on the rear panel. This is not
necessary if error correction is used since the HP 8720B Option H83
will compensate automatically. Test fixture components are shipped
with the instrument to include power splitter, load, attenuator,
adaptor and cables (See Figure 2).
MANUAL CHANGES NECESSARY TO DOCUMENT THE HP 8720B OPTION H83:
OPERATING MANUAL, SPECIFICATIONS
Page 1 to 14, HP 8720B System Specifications Tables (5 of 5):
1. All specifications which refer to frequency range below 2.0 GHz
are not guaranteed nor warranted due to the nature of the modifications. All standard specifications in the TEST configuration are considered typical
.
2. Dynamic range is increased from 85 dB to 100 dB in the HIGH POWERconfiguration with a
microwave amplifier (HP 8349B or equivalent). Dynamic accuracy will be degraded with power
greater than +10 dBm at the test ports. Operation
below 2 GHz is not recommended, however, the unit will
operate normally from 2 GHz to 20 GHz with the exception
that nominal power at the test ports will be +10 dBm.
3. No phase compensation for the delay of the reference arm has
been designed into the HP 8720B Option H83. If required by the user,external delay must be
added to the reference arm for the
configuration selected.
4. In the BYPASS configuration the HP 8720B Option H83 operates the
same as the TEST configuration. However, below 2 GHz the
power at the test ports will increase. This is attributed to
the coupling factor of the reference arm decreasing as the
frequency goes below 2 GHz.
The above manual changes apply to all specifications listed throughout the HP 8720B manual set.
SERVICE MANUAL, TROUBLESHOOTING (AND BLOCK DIAGRAM)
Page 5, HP 8720B Overall Block Diagram
Insert Figure 1 Partial RF Block Diagram into Overall Block Diagram
HP 8720B-H83
Page 6 of 7
REPLACEABLE PARTS:
SERVICE MANUAL
Page 8, Replaceable Parts
Delete: A67 HP P/N 5086-7408 POWER SPLITTER
Delete: A68 HP P/N 0955-0216 MICROWAVE ATTENUATOR
Add: A80 HP P/N 0955-0148 COUPLER
Add: Item 81 HP P/N 08720-00011 COUPLER BRACKET
Add: Item 82 HP P/N 08720-00012 SPACER, flat
Page 10, Replaceable Parts
Delete: W23 HP P/N 08720-20067 RF CABLE - A64J2 RF IN/A68
Add: W50 HP P/N 08720-20006 RF CABLE - A57/REF IN
Delete: W32 HP P/N 08415-20070 RF CABLE - A69/A67
Add: W51 HP P/N 08720-20002 RF CABLE - A69/COUPLER, output
Delete: W34 HP P/N 08415-20076 RF CABLE - A58/A67
Add: W52 HP P/N 08415-20003 RF CABLE - A58/RF OUT
Add: W53 HP P/N 08720-20004 RF CABLE - COUPLER, input/RF IN
Add: W54 HP P/N 08720-20005 RF CABLE - COUPLER, arm/REF OUT
Add: W55 HP P/N 08720-20007 RF CABLE - RF IN/RF OUT
Add: W56 HP P/N 08720-20007 RF CABLE - REF IN/REF OUT
Add: A90 MFR P/N 34078 10 DB PAD - A64J2 RF IN (R SAMPLER)
Page 18, Replaceable Parts
Change Item 12 (19A/20B) REAR PANEL to HP P/N 08720-00020 REAR PANEL, lower
Add: Item 20 HP P/N 1250-1753 COAXIAL CONNECTOR, rear panel Qty (4)
NOTE: The following parts comprise the rear panel test fixture.
Add: HP P/N 5086-7408 POWER SPLITTER QTY (1)
Add: HP P/N 08720-20014 RF CABLE - SPLT OUT/REF IN QTY (1)
Add: HP P/N 08720-20013 RF CABLE - RF OUT/SPLT IN QTY (1)
Add: HP P/N 0960-0053 50-OHM LOAD SMA(M) - REF OUT QTY (1)
Add: HP P/N 1250-1159 ADAPTOR - RF IN SMA(M)-SMA(M) QTY (1)
Add: MFR# 34078 MODEL 290 10 dB ATTENUATOR - REF IN QTY (1)
HP 8720B-H83
Page 5 of 7
HP 8720B OPTION H83
SIGNAL SEPARATION
.
RF OUT RF IN
A58 MODULATOR
W55
REF OUT REF IN
W52 W53
A80 DIRECTIONAL COUPLER
THE ABOVE ITEMS REPLA CE THE S TANDARD
POWER SPL ITTER AND 20 dB PAD AS SHO WN BELOW
A67 POWER SPL ITTER
W56
Rear panel
A90 10dB
W54
A68 20dB
ATTEN
ATTEN
W50
W51
A 69
STEP ATTE N
R
S4 TRANSF ER SWIT CH
R
TO A69 STEP ATTEN
A61 BIAS TEE
A62 DIRECTIONAL COUPLER
A63 DIRECTIONAL COUPLER
A60 BIAS TEE
TEST: -10 dBm
HIGH POWER: +10 dBm
A
PORT 1
PORT 2
B
Figure 1 Partial RF Block Diagram
HP 8720B-H83
Page 7 of 7
SYSTEM CONFIGURATIONS
HP 8720B-H83 (INTERNAL)
16 dB
10 dB
RF OUT
RF IN
REF OUT
REF IN
BYPASS
HIGH
POWER
HP 8349B-H83
(OR EQUIVALENT)
3 dB
10 dB
TEST
50
10 dB
Figure 2
10 DB PAD
A64J2 RF IN
FRONT
A69
08720-20002
COUPLER
0955-0148
SPACER
08720-00012
08720-20006
08720-20005
Figure 1
8720B-H83
A58
08720-20007
COUPLER BRACKET
08720-00011
08720-20004
08720-20003
08720-20007
SPECIAL REAR PANEL
08720-00020
RF OUT
RF IN
TEST
08720-20013
RF OUT/SPLT IN
POWER SPLITTER
ADAPTOR SMA(M)-SMA(M)
08720-20014
SPLT OUT/REF IN
REF OUT
REF IN
5O-OHM LOAD
50
10 dB ATTN
10 dB
rear panel
Figure 2
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