Boonton 92BD User manual

BOONTON
INSTRUCTION
MANUAL
MODEL
928D
PROGRAMMABLE
RF
MILLIVOLTMETER
b-877

b-877
INSTRUCTION
MANUAL
MODEL
928D
PROGRAMMABLE
RF
MILLIVOLTMETER
b-877
TEL:
201-887-5110
TWX:
710-986-8241
ROUTE
287
AT
SMITH
ROAD
PARSIPPANY,
N.J.
07054
USA

TABLE OF CONTENTS
CHAPTER
Io GENERAL INFORMATION
1.1 GENERAL
1 0 2 EQUIPMENT DESCRIPTION
1 0 2 0 1 Wide
Frequency Range
1.2.2
Wide
Voltage Range
1.2.3
True
RMS Response
1o2.4 Low Noise
1.2.5
Minimal Zero Adjustment
1.2.6 BCD Output
1.2.7
DC Analog Output
II. SPECIFICATIONS
III o OPERATION
3.1 INSTALLATION
3.1.1 Operating Controls and Indicators
3.2 OPERATING PROCEDURES
3.2.1 Initial Operating Procedure
3.3 OPERATING NOTES
3.3.1 Overload Limits
3.3.2 Connection for Measurements Below 100 MHz
3.3.3 Connection for Measurements Above 100 MHz
3.3.4 Low-Level Measurement
3.3.5 Over/Under Range Indication
3.3.6 Making the Zero Adjustment
3.3.7 Signal Overload on 1 mV Range
3.3.8 Temperature Effects
3.3.9 Hum, Noise, and Spurious Pickup
3.4 LINEAR DC OUTPUT
3.5 LOW-FREQUENCY MEASUREMENTS
92BD
b-877
i
PAGE
2
3
3
4
4
4
5
5
11
11
11
12
12
13
13
13
13
14
14
16
16
16
17
17
17

TABLE
OF
CONTENTS
(CONTINUED)
CHAPTER
306
CORRECTION
CURVES
FOR
ACTUAL
VOLTAGE
vs
0
DC
OUTPUT
3.7
CORRECTION
CURVE
FOR
MODEL
91-BB
3.8
CORRECTION
CURVE
FOR
MODEL
91-14A
IVo
THEORY
4o1
GENERAL
4.
10 1 RF
Probe
4.1.2
Attenuator
and
Amplifiers
4.1.3
Synchronous
Detector
4.1.4
Shaping
Amplifier
4o1o5
Digital
Control
4 0
106
Analog/Digital
Converter
4o1.
7
Chopper-Driver
Circuits
4o
1o8
Power
Supply
4o1o9
Programming
V.
MAINTENANCE
5.1
PERIODIC CALIBRATION
5.2
PRECAUTIONS
WHEN
CHECKING
CALIBRATION
5o3
CALIBRATION
CHECK
5.4
CALIBRATION
PROCEDURE
5.5
TROUBLESHOOTING
PROCEDURE
5,5.1
Cover
Removal
92BD
b-877
5.5.2
Chopper
Replacement
5.5.3
Voltage
and
Resistance
Tests
5,5.4
Test
Points
5.5.5
Replacement
of
RF
Probes
5,5,6
Probe
Tests
ii
PAGE
17
17
17
20
20
20
21
21
22
22
22
22
23
23
23
23
24
24
24
27
27
27
27
27
27
27

TABLE
OF
CONTENTS
(CONTINUED)
CHAPTER
VI,
INTERFACE
INFORMATION
6.1
PROGRAMMING
INPUTS
6.1.1
Input
Characteristics
6.1.2
Input
Pull-Up
6.1.3
Triggering
6.2
DATA
OUTPUTS
6.2,1
Output
Characteristics
6.2.2
Analog
Output
6.3
WAVEFORMS
6.3.1
Encode
Trigger
6.3.2
Data
Output
Timing
6.4
AUTORANGING
CHARACTERISTICS
SCHEMATICS
Amplifier
Chopper
Driver
Shaping
Amplifier
Autorange
Digital
Control
Counter
Board
A/D
Converter
Display
Board
92-8A
92-9A
830581
Sheet
830581
Sheet
830456
Sheet
830483
830581
Sheet
830546
Sheet
830546
Sheet
830546
Sheet
830650
830900
CHARTS
AND
DRAWINGS
FIGURE
of
3
of
3
of
2
of
of
3
of
2
of
3
3
3
3
3
3
3
Input
Resistance
of
RF
Probe
as
a
Function
of
Input
Level
and
Frequency
2
Input
Capacitance
vs.
Input
Level
of
Model
91-12F
Probe
(Measured
at
10
MHz)
3
Typical
VSWR
of
Model
91-12F
RF
Probe
with
Model
92-8B
50 n
Adapter
4
Typical
VSWR
of
Model
91-12F
RF
Probe
with
Model
91-14A
Type
N
Tee
Adapter
and
91-15A
50
n
Termination
92BD
b-877
iii
PAGE
34
34
35
35
35
36
36
36
36
37
38
Endpapers
PAGE
9
10
10
10

CHARTS AND DRAWINGS (CONTINUED)
FIGURE
5
Method for making low-inductance connections to test signal point directly
the RF probe
6 Assembly of Model 91-14A Type N Tee Adapter
7 Down-Scale correction Curves, Recorder Output
8A Model 91-SB 50 n Adapter correction curve
8B Model 91-14A Type N Tee Adapter Correction Curve
9 Model 92BD Block Diagram
10 Frequency Response Test Setup
11 Swept Frequency Response Test Setup
12 Calibration Instructions
13 External Connections
TABLE NO.
Required Accessories
Crest Factors
TABLES
2
3
4
Model 92 Series Controls and Indicators
Connection Recommendations
TABLE OF REPLACEABLE PARTS
92BD
b-877
iv
using
PAGE
15
15
18
19
19
20
30
31
33
38
PAGE
8
9
11
14
39

I.
GENERAL
INFORMATION
1.1
GENERAL
One
of
the
Model
92
Series
of
RF
Millivoltmeters,
the
Model
92BD
provides
digital
readout
of
measurements
from
the
low
radio
frequencies
to
the
gigahertz
region,
over
a
voltage
range
of
200
µV
to
3
volts.
It
is
a
programmable,
solid-state
instrument
of
high
sensitivity
and
accuracy.
The
Model
92BD
exhibits
true
rms
response
for
input
signals
up
to
30
millivolts,
gradually
approaching
peak-to-peak
above
this
level.
The
digital
voltmeter,
however,
is
calibrated
in
rms
above
this
region.
The
instrument
is
characterized
by
high
input
impedance
(see
Figures
1
and
2),
excellent
stability,
and
low
noise.
A
small
edgewise
panel
meter,
calibrated
in
dBm,
is
included;
this
is
necessary
for
zeroing
the
instrument
(the
digital
display
blanks
out
below
200
µV),
and
will
also
serve
for
comparative
measurements
of
acceptable
accuracy.
A
binary
coded
decimal
(BCD)
output
is
provided
at
a
rear
connector,
permitting
the
92BD
to
be
integrated
in
systems
for
driving
printers,
tape
or
card
punches,
data
control
units,
and
simi-
lar
interfacing
data
equipment.
As
part
of
a
system,
the
92BD
is
also
programmed
and
controlled
externally
as
needed.
A
linear
de
output,
whose
level
is
proportional
to
the
rf
input
voltage,
is
also
provided
at
a
rear
connector.
This
may
be
used
to
drive
a
recorder,
remote
indicator,
or
other
analog
devices.
The
92BD
offers
a
convenient
and
accurate
means
for
making
a
wide
variety
of
measurements.
Typical
uses
of
this
instrument
would
include:
In
transistor
testing
the
instrument
may
be
used
to
measure$,
ft'
and
other
transistor
parameters.
VSWR
and
return
loss
measurements
using
the
Model
92
Series
with
bridge
methods,
directional
couplers,
and
adjustable
or
slotted
lines.
92BD
b-877
Gain
and
loss
measurements
in
wide-band
amplifiers,
including
such
design
characteristics
as
stage
gain,
flatness
of
the
pass
band,
upper
cutoff
or
corner
frequency,
negative
feedback
factors,
and
other
parameters.
Proper
adjustment
of
tuned
circuits
in
narrow-band
amplifiers.

The
adjustment,
measurement
of
performance,
and
evaluation
of
parameters
of
rf
filters.
Measurement
of
vswr
or
return
loss
and
attenuation
of
rf
attenuators,
Measurement
of
output
levels
of
signal
generators,
adjustment
of
baluns,
harmonic
distortion
of
rf
signals,
and
adjustment
of
circuits
for
minimum
voltage
(null)
or
maximum
voltage
(peak).
The Model
92BD
is
available
in
several
optional
configurations
with
a
basic
accuracy
of
1%
rdg.
+
1%
fs.
The
standard
features
of
the
instrument
are:
Programmable
(logic
level).
Measures
from
200
µV
to
3
V*
from
10 kHz
to
1.2
GHz.
True
rms
response
to
30 mV**·
Convenient
push-button
ranging.
BCD
digital
output
plus
de
analog
output.
High
input
resistance,
low
input
capacitance.
Overload
protection
to
400
Vdc,
10
Vac.
VSWR
less
than
1.15
up
to
1.2
GHz.
*To 300 V,
up
to
700
MHz,
with
accessory
100:1
divider.
**To 3 V,
up
to
700
MHz,
with
accessory
100:1
divider.
The
characteristics
of
the
instrument
include:
high
reliability,
fast
warm-up
(1
minute),
long
intervals
between
calibrations,
plug-in
PC
boards
for
ease
in
servicing,
light
weight,
and
other
advantages
of
solid-state
design.
1.2
EQUIPMENT
DESCRIPTION
The
Model
92BD
is
basically
a
programmable
analog
instrument
with
digital
readout.
It
is
available
with
a
full
range
of
options
and
accessories
as
described
in
Chapter
II.
Input
range
programming
by
logic
level
command
is
standard.
The
instrument
is
sensitive,
accurate,
sturdily
constructed,
and
protected
against
overloads.
It
will
perform
over
extended
periods
of
time
without
failure
or
need
for
recalibration.
It
is
92BD
b-877
2

packaged
as
a
compact
bench
instrument
that
can
be
easily
mounted
in
a
standard
19-inch
rack
using
an
inexpensive
hardware
kit.
Important
input
and
accuracy
specifications
are
reproduced
on
a
reference
plate
fastened
to
the
exterior
top
cover
of
the
instrument.
Clips
for
holding
out-of-use
accessories
are
provided
at
the
rear
of
the
instrument.
Calibration
instructions
are
reproduced
on
the
underside
of
the
top
cover
of
the
instrument.
Standard
accessories
supplied
with
the
Model
92
Series
include
one
each
of
the
following:
Model
91-12F
RF
Probe
with
low-noise
cable
and
connector.
Model
92-8B
50-ohm
BNC
adapter.
Model
91-13B
Probe
Tip
(removable)
with
grounding
clip
lead.
A
complete
kit
of
probe
accessories
is
available
as
optional
equipment,
including
a
storage
case
with
space
for
the
Model
91-12F
RF
Probe
and
the
other
standard
accessories.
1.2.1
Wide
Frequency
Range
The
calibrated
frequency
range
of
the
Model
92BD
extends
from
10 kHz
to
1.2
GHz,
with
uncali-
brated
response
to
beyond
8 GHz.
Relative
accuracy
above
1.2
GHz
is
typically
±0.5
dB.
A
Model
91-8B
50-ohm
BNC
Adapter
is
supplied
as
a
standard
accessory
with
the
instrument
for
50-ohm
voltage
measurements
up
to
600
MHz. A
correction
curve
(Figure
SA)
is
included
for
fre-
quencies
above
50
MHz.
For
higher
frequency
measurements
and
for
through-line
voltage
measure-
ments
the
optional
accessory,
Model
91-14A
Tee
Adapter,
is
recommended.
It
is
designed
to
compen-
sate
for
the
rf
probe
capacitance
and
to
present
a
good
vswr
(better
than
1.15)
up
to
1.2
GHz.
It
may
be
used
in
conjunction
with
the
Model
91-15A
SO-ohm
load
for
terminated
voltage
measurements.
In
a
coaxial
line
its
insertion
loss
is
low;
however,
a
chart
(Figure
8B)
is
supplied
showing
loss
vs.
frequency.
See
Figure
4
for
typical
vswr.
An
optional
accessory,
the
Model
91-4C
RF
Probe,
has
a
frequency
range
of
1 kHz
to
250
MHz
for
lower
frequency
applications.
1.2.2
Wide
Voltage
Range
The
Model
92BD
has
eight
ranges,
from
1
millivolt
full
scale
to
3
volts
full
scale,
arranged
in
1-3-10
sequence.
No
attenuator
attachments
are
required
for
measurements
up
to
3
volts.
While
this
range
is
ample
for
most
rf
voltage
measurements,
the
capability
of
the
instrument
can
be
in-
creased
to
300
volts
(up
to
700
MHz)
by
using
the
optional
accessory,
Model
91-7C
100:1
Voltage
92BD
b-877
3

Divider.
Use
of
the
100:1
Voltage
Divider
also
increases
the
input
resistance
of
the
Model
91-4C
RF
Probe
by
a
factor
greater
than
100.
1.2.3
True
RMS
Response
The Model
92BD
provides
true
rms
response
for
signal
inputs
below
approximately
30
millivolts
(below
3
volts,
up
to
700
MHz,
with
the
Model
91-7C
100:1
Voltage
Divider).
As
the
input
level
increases,
the
waveform
response
gradually
approaches
peak-to-peak,
calibrated
on
the
indicator
in
rms.
Thus,
in
addition
to
making
precise
sinusoidal
voltage
measurements
at
all
levels,
the
in-
strument
measures
non-sinusoidal
or
asymmetrical
signals
within
therms
region
without
loss
of
accuracy.
1.2.4
Low
Noise
The Model
92BD
has
been
designed
and
constructed
to
hold
noise
from
all
sources
to
a minimum.
The
probe
cable
is
of
special
low-noise
design;
a
vigorous
flexing
causes
only
momentary,
minor
deflections
on
the
most
sensitive
range.
The Model
91-12F
Probe
is
not
sensitive
to
shock
or
vibration;
even
sharp
tapping
on
the
probe
barrel
causes
no
visible
deflection
on
any
range.
Amplification
takes
place
at
94 Hz,
reducing
susceptibility
to
any
50
or
60
Hz
line-frequency-
related
fields.
A
unique
circuit
reduces
the
low-level
noise
originating
from
the
mechanical
chopper
and
renders
the
instrument
immune
to
changes
in
chopper
performance
that
could
occur
with
the
passage
of
time.
1.2.5
Minimal
Zero
Adjustment
Zero
adjustment
is
not
required
on
the
upper
five
ranges
of
the
Model 92BD.
For
measurements
on
the
lower
three
ranges,
the
ZERO
control
is
set
on
the
most
sensitive
range
before
operation.
This
control
balances
out
small
thermal
voltages
in
the
probe
elements
and,
once
adjusted,
requires
only
infrequent
checking
during
the
course
of
subsequent
measurements.
1.2.6
BCD
Output
The Model
92BD
provides
a
serialized
binary
coded
decimal
output
(4-line,
8,
4,
2,
1)
for
connection
to
an
external
system.
When
the
92BD
is
an
integral
part
of
a
system
configuration,
it
may
be
remotely
controlled
and
triggered
automatically
in
synchronism
with
some
system
event.
For
systems
or
external
requirements,
all
input
and
output
connections
for
the
92BD
are
made
at
the
card-edge
connector
on
the
rear
of
the
instrument.
See
Figure
11
for
receptacle
connections.
92BD
b-877
4

1.2.7
DC
Analog
Output
The
92BD
also
provides
a
linear
de
output
whose
current
capability
of
1
mA
into
1000
ohms
is
extremely
stable.
Voltage
Range:
Full
Scale
Voltage
Range:
dBm
Range:
Frequency
Range:
Accuracy:
300
mV
to
3 V
100
µV
to
300
mV*
Indicators:
Digital
Analog
Power:
RFI:
92BD
b-877
II.
SPECIFICATIONS
200
µV
to
3 V
(300
V
up
to
700
MHz
with
accessory
100:1
voltage
divider).
1,
3,
10,
30,
100,
300,
1
000,
and
3000
mV.
-60
to
+23
dBm
(+63
dBm
up
to
700
MHz
with
option
accessory,
Model
91-7C
100:1
Voltage
Divider).
10
kHz
to
1.2
GHz
(uncalibrated
response
to
approximately
8
GHz).
1
mV
to
3 V
1%
2%
10
kHz
rdg.
rdg.
50
kHz
1%
1%
rdg.
fs
plus
150
MHz
3%
rdg.
*Below
mV,
add
1%
fs
700
MHz
10%
7%
rdg.
rdg.
1.
2
GHz
LED, 4
digits,
f.s.
counts
of
3000
and
1000.
Full
4-digit
display
with
dB
option,
0.01
dB
resolution.
Blanked
at
5%
over
and
below
20%
f.s.;
decimal
point,
units,
and
polarity
for
dBm.
Miniature
edgewise
type,
calibrated
-9
to
+3
dBm,
50
n.
115
or
230
V
±10%,
50
to
400
Hz.
There
is
no
detectable
radiated
or
conducted
leakage
from
instru-
ment
or
probe.
5

Temperature:
Waveform
Response:
Crest
Factor:
Input
Impedance:
VSWR:
Power
Sensitivity:
Data
Outputs:
Commands:
Analog
Output:
Dimensions:
Weight:
Accessories
Furnished:
92BD
b-877
In
accordance
with
ANSI (ASA)
Spec.
39.7.
Temperature
Influence
Temperature
Range
Instrument
RF
Probe
Ref.
21°c
to
25°C
0 0
Normal,
18°C
to
30°c
0
±1%
rdg
Severe,
10°c
to
40°C
±1%
rdg
±4%
rdg
True
rms
response
for
input
levels
up
to
30
mv
(3
V
to
700
MHz
with
100:1
Voltage
Divider),
with
transition
to
peak-to-peak
(calibrated
in
rms
at
higher
levels).
420
to
1.4
depending
upon
input
level
(see
Table
2).
See
Figures
1
and
2.
Less
than
1.20
to
1.2
GHz
(Return
Loss
greater
than
21
dB).
See
Figures
3
and
4.
200
pW,
minimum
detectable
power
in
50
ohms.
1-2-4-8
BCD
data,
serial
by
digits.
1-2-4
range
information.
Overrange,
underrange,
encode
complete.
Logic
0,
0.7
V;
logic
1,
2.4
to
5.25
v.
Logic-level
inputs
select
input
ranges,
mV, dBm,
and
autoranges
(with
options),
encode
hold,
encode
trigger,
manual
disable,
TTL
compatible.
Logic
0 =
0.7
V;
logic
1,
2.4
to
5.25
V.
Oto
10
Vdc,
proportional
to
rf
input
voltage.
9
kn
source
resistance.
5.2"
H,
8.3"
W,
11.5"
D
(132
X
211
X
292
mm).
Net
9
lbs.
3
oz.
(4.1
kg)
(with
standard
accessories).
Model
91-12F,
RF
Probe.
RF
Probe
with
low-noise
cable
and
con-
nector
assembly
for
measurements
from
10
kHz
to
1.2
GHz;
see
Figures
1
and
2
for
input
resistance
and
capacitance.
6

Accessory Kit (Optional)
Model 91-24A:
Other Accessories (Optional)
Available:
928D
b-877
Model 91-138, Probe Tip. Removable Probe Tip with grounding clip
lead; for use up to approximately 100 MHz.
Model 91-88, 50 Q 8NC Adapter. Used for measurements up to 600
MHz with a 50-ohm system; for VSWR see curve of Figure 3.
Model 91-6C, Unterminated 8NC Adapter. used for coaxial connec-
tion up to approximately 100 MHz, or to 400 MHz when fed from a
50-ohm source in an electrically short system.
Model 91-7C, 100:1 Voltage Divider. Attenuates input signal by a
factor of 100 (±1% plus ±1%/100 MHz), permitting measurements up
to 300 volts and extending therms measuring range to 3 volts; in-
creases input resistance by a factor of 100; operates from 50 kHz
to 700 MHz. Maximum input potential, 1000 volts, de plus peak ac.
Model 91-14A, 50 Q Tee Adapter. Type N Tee Connector; with Model
91-15A Termination (see below) permits connecting into 50-ohm
line; required for measurements above approximately 100 MHz; for
VSWR see curve of Figure 4.
Model 91-15A, 50 Q Termination. Type N 50-ohm termination for use
with Model 91-14A Tee Connector.
Model 91-18A, Storage Case. Case for protecting and storing
Model 928 accessories.
Model 91-4C, Special 1 kHz to 250 MHz RF Probe. Low-frequency
probe for measurements ranging from 1 kHz to 250 MHz; input re-
sistance essentially the same as that of Model 91-12F, RF Probe.
Model 91-16A, Unterminated Type N Adapter. May be used with all
probes. Used for coaxial connection up to approximately 100 MHz,
or to 400 MHz when fed from a 50-ohm source in an electrically
short system.
Model 92-1A, Single Rack Mounting Kit. Kit for mounting one 928D
as one-half of a module in a standard 19-inch rack.
Model 92-18, Double Rack Mounting Kit. Kit for mounting two 928D's
side-by-side in a standard 19-inch rack.
7

Standard
Equipment
Options:
Model
92BD-01.
Autoranging
option;
provides
for
automatic
range-
switching
controlled
by
the
level
of
the
input
voltage.
Model
92BD-08.
Rear
Probe
connection.
Model
92BD-09.
dBm
and
mV
readout.
Model
92BD-10.
75
Q
dBm
display;
with
91-BB/1
75
Q
BNC
adapter.
Model
92BD-16.
Serial
to
parallel
data
output
converter.
NOTE:
Special
equipment
options
can
be
supplied
to
customer's
specifications.
IMPORTANT
NOTE: To
fully
exploit
the
capabilities
of
this
instrument,
the
accessories
listed
below
are
required
for
the
indicated
ranges
of
operation.
Table
1.
Required
Accessories
MEASURING
RANGE
REQUIRED
ACCESSORY
REMARKS
100
MHz
to
600
MHz
Model
91-BB
50
n
Adapter
for
Supplied
as
standard
equipment
shielded
connection
to
50-ohm
with
the
Model
92
Series.
line;
other
impedances
avail-
able
on
request.
Above
600
MHz
Model
91-14A
Tee
Connector
Available
separately.
and
91-15A
50
n
Termination
for
connection
into
50-ohm
line.
1
kHz
to
250
kHz
Model
91-4C
RF
Probe
Available
separately.
Input
levels
up
to
300
V;
Model
91-7C
100:1
Voltage
Available
separately.
rms
response
with
levels
to
Divider;
operates
over
fre-
3 V
quency
range
from
50
kHz
to
700
MHz
92BD
b-877
8

Table
2.
Crest
Factors
VOLTAGE
RANGES
(mV)
AND
CREST
FACTORS
VOLTAGE
RANGES
(mV)
1 3
10
30
100*
300*
CREST FACTOR**
420
70
21
7
420
70
to
to
to
to
to
to
42
14
4.2
1.4
42
14
*With
accessory
100:1
Voltage
Divider
(see
Table
1).
**Maximum
permissible
ratio
of
peak
to
rms
value
of
voltage.
IOM I
"T "T
7
777
830363
INPUT RESISTANCE
OF
BEC
RF
PROBES
5M
ZM
3V
(/)
IM
~
J:
---
i,.r---...
-
IV
0. "-lo...._
w
(.)
500K
z
~
(/)
en
..........
300mV
.....
r---....._
1000*
21
to
4.2
..
'-
"
r\.
"- \
'"
\
w
a:
I-
ZOOK
IOOmV
~~
'\
.....
~
f\.
::>
Q.
~
IOOK
-......
f\ '
30mV
"'
IOmV
.....
~
i\.
-
.....
"
lmV
-
.....
"
..........
'
"'
..._r,....
'I "
50K
""
"'\.
'I~
I\
~
\.\
~
20K
IOK
3000*
7
to
1.
4
I\T\
~
"
\
~
~
"'
'
" ''
'
\.
\ '
\.
'\
\.
~
\\
' \
\'
"'
~
'
~f\
\ \
~~
'~
I'
~l\\
~~
~
' '
' '
'''
'
"
'\
'I
"'
5K
01
0,2 0,5
5
10
20
50
100
200
92BD
b-877
FREQUENCY (MHz)
Figure
1.
Input
Resistance
of
RF
Probe
as
a
Function
of
Input
Level
and
Frequency
9

8303!12
1.0
1-------1~--1---------1---
........
--4-----------'
0
'--------''---...I......--_.__
____
.,__
_ __._
__
---'---------'
0.01
0.03
0,0!1
0.1
o,3
o.,
1.0
3.0
RF
TEST
V0LTAGE,(V)
Figure
2.
Input
Capacitance
vs.
Input
Level
of
Model
91-12F
Probe
(Measured
at
10
MHz)
830381
1.2
r-----+---+---1---+-+--1---l-LL_J
MHz
Figure
3.
Typical
VSWR
of
Model
91-12F
RF
Probe
with
Model
92-SB
50
Q
Adapter
a:
~
<I)
1.2
>
1.1
r.o
830352
VIII/I/II#
////1//4
100
.I I
1///II///I//,
'/////Ill.
200
I////
l!tlo/&,
///N0IIIINAL,
300
r~
o//4
/II
I
400
MHz
'--
"
"I'//,
[W
'///IL
711,
",
"
'I
r'
//
\1/@,
,111/
'1711.
rw;,
1///1,
l'i't'l
172
"
500
700
1000
Figure
4.
Typical
VSWR
of
Model
91-12F
RF
Probe
with
Model
91-14A
Type
N
Tee
Adapter
and
Model
91-15A
50 n
Termination
92BD
b-877
10

III. OPERATION
3.1 INSTALLATION
The Model 92BD has been inspected and tested at the factory before packing, and is shipped
ready for operation. If there is any indication of shipping damage, immediately notify the car-
rier before attempting to put the instrument into operation.
3.1.1 Operating Controls and Indicators
The controls and indicators installed on the Model 92BD are shown in Table 3.
Table 3. Model 92 Series Controls and Indicators
ITEM FUNCTION
Selector
FULL SCALE Range
Indicators
Digital:
Analog:
PROBE (Jack)
ZERO (Control)
92BD
b-877
This switch turns on the instrument power, and if the instrument is the
92BD-09 option, selects either mV or dBm readout.
These range pushbuttons (1, 3, 10, 30, 100, 300, 1000, and 3000 mV), and
(-SO, -40, -30, -20, -10, o, +10, and +20 dBm) select the operating range.
The AUTO pushbutton, for the 92BD-01 option, switches the instrument to the
automatic ranging mode.
LED, 4 digits, f.s. counts of 3000 and 1000. Full 4-digit display with dB
option, 0.01 dB resolution. Blanked at S% over and below 20% f.s.; decimal
point, units, and polarity for dBm.
Miniature edgewise type, calibrated -9 to +3 dBm, SO n.
The probe cable connects to the instrument through this PROBE jack. Always
check that the knurled ferrule nut of the probe cable connection is tight-
ened when in use.
This control i.s used to zero the instrument.
11

The
following
items
are
on
the
rear
panel:
Fuse
Holder
and
Fuse
Slide
Switch
Recorder
Output
Terminals
Component
Holders
(Clips)
REMOTE
CONNECTIONS
(Use
with
Amphenol
225-222221-101
con-
nector
or
equivalent)
A
fuse
holder
is
located
on
the
rear
panel
for
installing
either
a
0.20
am-
pere,
115
V,
or
a
0.1
ampere,
220
V,
Bussman
MDL
SLO-BLO
fuse.
Switch
that
is
set
to
115
V
or
230
v,
according
to
the
available
power
source.
Be
sure
that
the
proper
fuse
is
located
in
the
fuse
holder.
A
DC
voltage
proportional
to
the
indicator
reading
is
available
at
these
terminals.
F.
s.
output=
+10
V;
output
resistance=
9 kn.
Three
component
holders
or
component
clips
are
located
at
the
rear
panel
for
securing
accessories
which
are
not
in
use.
A
card
edge
connector
is
mounted
at
the
rear
of
the
instrument.
See
Figure
13
for
the
pin
designations.
This
safety
requirement
symbol
has
been
adopted
by
the
International
Electro-
technical
Commission,
Document
66
(Central
Office)
3,
Paragraph
5.3,
which
directs
that
an
instrument
be
so
labeled
if,
for
the
correct
use
of
the
instrument,
it
is
necessary
to
refer
to
the
instruction
manual.
In
this
case
it
is
recommended
that
reference
be
made
to
the
instruction
manual
when
connecting
the
instrument
to
the
proper
power
source.
Verify
that
the
right
fuse
is
installed
for
the
power
available
and
that
the
0.20
A
and
0.10
A,
50-400
Hz
switch
on
the
rear
panel
is
set
to
the
applicable
operating
voltage
of
115
V
or
230
V.
3.2
OPERATING
PROCEDURES
In
the
following
paragraphs,
the
initial
operating
procedure
for
the
92BD
is
described,
as
well
as
operating
notes
and
recommended
connection
methods.
3.2.1
Initial
Operating
Procedure
92BD
b-877
a.
Be
sure
that
the
serial
number
of
the
probe
to
be
used
is
the
same
as
that
of
the
Model
92BD.
(Each
instrument
is
calibrated
for
its
particular
rf
probe.)
Use
of
a
probe
other
than
that
for
which
the
instrument
was
calibrated
may
result
in
measurement
errors.
12

b. Connect the probe cable to the PROBE jack on the front panel.
c. Check the setting of the power switch on the rear panel to be sure that it is set to the
proper position for the line voltage available.
d. Plug the instrument's power cable into a power receptacle and turn the selector switch to
mv. Allow a minute for the instrument to warm up.
e. Press the 1 mV range button; the panel meter pointer should rest on the zero reference
line. If it does not, use the ZERO control to set the meter to zero. (This adjustment
will hold for the other ranges.) The 92BD is now ready for use. (See 3.3.4.)
3.3 OPERATING NOTES
While using the Model 92BD is a direct and straight-forward process, there are certain pre-
cautions and procedures which must be observed to obtain satisfactory results.
3.3.1 Overload Limits
The Model 91-12F RF Probe supplied with the Model 92BD is overload-protected to 10 volts, ac,
and to 400 volts, de. EXCEEDING THESE LIMITS MAY RESULT IN PERMANENT DAMAGE TO THE PROBE.
The Model 92-8B SO-ohm Adapter should not be subjected to continuous overload of more than
10 volts (de+ rms ac) to avoid excessive heating of the terminating resistor.
Where voltages above these limits are likely to be encountered, the Model 91-7C 100:1 Voltage
Divider is requiredo Maximum rating of the Voltage Divider is 1000 volts de+ peak ac.
3.3.2 Connection for Measurements Below 100 MHz
The RF Probe supplied with the Model 92BD is equipped with a detachable tip and ground lead.
For measurements of signals below approximately 100 MHz, this tip provides a convenient means for
both signal and ground connection.
3.3.3 Connection for Measurements Above 100 MHz
For frequencies above 100 MHz, the probe tip should not be used with the Model 92BD. Connec-
tion should be made directly to the center contact of the probe with the ground connection kept as
short as possible (see Figure 5).
92BD
b-877
13

The
connection
recommendations
outlined
in
Table
4
should
be
followed
to
maintain
specified
accuracy.
Table
4.
Connection
Recommendations
FREQUENCY
SIGNAL
CONNECTION
Up
to
100
MHz
Probe
Tip
and
ground
lead
(supplied)
100
MHz
to
250
MHz
250
MHz
to
600
MHz
Beyond
600
MHz
Probe
without
tip
(see
Fig.
5)
(supplied)
Probe
with
Model
91-8B
50 Q
BNC
Adapter
(supplied)
Probe
with
Model
91-14A
Type
N
Tee
Adapter
and
Model
91-15A
Type
N
50
n
Termination
(see
Figure
6)
(optional
accessories)
3.3.4
Low-Level
Measurement
The
Model
92BD
will
provide
reliable,
reproducible
measurements
of
signal
levels
as
low
as
200
microvolts.
Preliminary
zero
adjustment
is
essential
when
using
the
lowest
range
scale
to
achieve
the
specified
accuracy,
and
is
strongly
recommended
for
all
ranges
up
to
30
millivolts.
When
the
instrument
is
to
be
used
on
the
1 mv
range,
the
following
zero
adjustment
procedure
should
be
followed:
a.
Set
the
FULL
SCALE
range
selector
to
the
1
mV
position.
b.
Be
sure
that
no
voltage
is
applied
to
the
probe,
and
that
it
is
adequately
shielded
from
local
fields.
This
can
be
done
by
partially
unscrewing
the
probe
cap
until
the
tip
just
breaks
contact
with
the
internal
connector,
leaving
the
metal
shell
engaged
with
the
body
threads.
Alternately,
the
probe
tip
can
be
removed
and
the
50-ohm
termination
(Model
91-8B)
mounted
in
its
place.
c.
Adjust
the
ZERO
control
to
bring
the
edgewise
meter
reading
to
zero.
Noise,
in
the
vicini-
ty
of
zero,
may
cause
the
reading
to
fluctuate
up
to
±5%
of
full
scale.
Adjust
the
ZERO
control
so
that
the
reading
averages
zero.
3.3.5
Over/Under
Range
Indication
When
the
rf
voltage
applied
to
the
probe
is
approximately
5%
above
the
maximum,
or
12%
below
the
minimum,
of
the
range
in
use,
the
digital
indicator
will
blank
out.
In
this
case,
switch
to
the
next
appropriate
range.
92BD
b-877
14