Motorola S1051C User manual

MOTOROLA INC., COMMUNICATIONS DIVISIÓN - INSTRUCTION MANUAL
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MOTOROLA trans istorized voltmeter
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68P81021A05-C

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AEPD-9830-O(CE2286-V21)
05 MOTOROL
MOTOROLA
MOTOROLA
TRANSISTORIZED
AC
VOLTMETER
A
MODEL 51053С
TRANSISTORIZED AC VOLTMETER
INC.
MODELS 51051С AND S1053C
COMMUNICATIONS DIVISION
ENGINEERING PUBLICATIONS
Copyright 1973 by Motorola, Inc.
Printed in WS. A.
2/27/73-UP
1301 E. ALGONQUIN ROAD
SCHAUMBURG, ILLINOIS 60172
68P81021A05
Issue - C

GUARANTEED
PERFORMANCE
SPECIFICATIONS
MODELS $1051C $1053C
(battery operated) (a-c/battery operated)
MEASUREMENTS 1 millivolt to 300 volts full scale on 12 ranges. -72 db to +52 db on
12 ranges.
+2% of full scale from 50 cps to 300 kc and
+3% of full scale from 20 cps to 50 cps, 300 kc to 1 mc;
except £376 of full scale from 20 cps to 100 kc and +5% of full scale
from 100 kc to 1 mc on the 300 volt range (at 259C (779F)).
1 to 300 mv range; greater than 1 megohm shunted by 30 uuf.
ШОШ ЫОМЕ E UE 1 {о 300 volt range; greater than 10 megohms shunted by 15 uuf
OVERLOAD VOLT range: Maximum of 550 volts (sum of d-c and a-c peak voltages)
PROTECTION MILLIVOLT range: Maximum of 110 volts rms continuous; 220 volts
rms for 10 seconds or less; 600 v d-c
NOISE Less than 0.1 mv meter deflection with input terminated with 100K
ohm resistor (shielded) on 1 mv range
METER
Linear voltage scales: 0-1 and 0-3 (calibrated to rms values of a sine
CALIBRATION
ACCURACY
wave)
Voltage ranges: 1, 3, 10, etc. steps
DB scale calibration: -12 to 42
Zero level: 1 milliwatt in 600 ohms
0-50 microampere taut-band movement
AC INPUT REQUIRE- 105-130 v а-с, 50-400 cps at approximately 5 ma; or, using SKN6009A
MENTS (51053С ONLY) 230/117 v a-c adapter cable kit, 230 v a-c, 50-400 cps
DC
INPUT
An
8.4
volt
mercury
battery
(Mallory
No.
TR-136
or
equivalent)
REQUIREMENTS
BATTERY LIFE Used as a ЕДЕН; Зоро шау 400 hours
Used as an amplifier: approximately 300 hours
METER
Output
voltage
(at
400
cps):
Proportional
to
input
voltage
as
indicated
by
meter
deflection
(meter
and
amplifier
are
separate
functions
and
cannot
be
used
simultaneously),
1.4
volts
(peak
to
peak)
or
0.5
volt
(rms)
into
600
ohm
(or
more)
resistive
load
corresponding
to
full
scale
meter
reading.
AMPLIFIER
CHARACTERISTICS
Frequency response: +0.5 db from 20 cps to 100 kc, approx. 3 db down
at 1 mc into 600 ohm or more (resistive load) and shunt capacity not
more than 200 uuf,
Distortion
(20-30*C):
Less
than
1%
with
ІК
ohm
(or
more)
resistive
load
shunted
by
not more
than
200
uuf
from
20
cps
to
20
kc.
Maximum
voltage
gain
(400
cps):
500
(54
db)
on
1
mv
range
WEIGHT
6
1b.
7
oz.
DIMENSIONS
10-1/4"
x
6-1/2"
x
5-3/4"
(approx.)
SPECIFICATIONS
SUBJECT
TO
CHANGE
WITHOUT
NOTICE
ii

MOTOROLA
MODEL CHART
TRANSISTORIZED AC VOLTMETERS
DESCRIPTION
[x]
Ш
ITEM INCLUDED
230/117 V ADAPTER CABLE KIT BATTERY KIT
OPTIONAL ACCESSORY
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MODEL DESCRIPTION MODEL
51051С PORTABLE, BATTERY POWERED SLN6013C Ој |
51053С PORTABLE, BATTERY AND АС POWERED SLN6045C o| xl
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iii

FOREWORD
CLAIM FOR DAMAGE IN SHIPMENT
If any damage to the shipping container is ap-
parent upon receipt, the delivering driver should
be requested to note such damage on all copies of
thefreight bill. This is for your protection should
the material have received damage.
The equipment should be unpacked immedi-
ately, examined for damage and tested. ЊЕ. GUE
fails to operate properly, or is damaged in any
way, а claim should be filed with the carrier.
The claim should be filed within 48 hours after
receipt, if possible, or during a period not to
exceed 15 days.
A full report of such damage should be ob-
tained from the claim investigator, who will call
upon you. For the purpose of this report, the
shipping container and all packing materials
should be retained for the investigator to examine.
Тһе investigator's report should then be for-
warded to:
Motorola Communications & Electronics, Inc.
Parts and Service Department
1301 E. Algonquin Road
Schaumburg, Illinois 60172
Include model number and serial number
when referring to the instrument for any reason.
iv
Arrangements for repair or replacement will be
made and you will be advised of the disposition of
the instrument.
REPAIR AND/OR RECALIBRATION
Because of its complexity it is recommended
that the instrument be returned to the factory for
repair and/or calibration. Return to:
Motorola Communications & Electronics, Inc.
Parts and Service Department
1301 E. Algonquin Road
Schaumburg, Illinois 60172
Before shipping the instrument notify the De-
partment at the above address of the service re-
quired. Refer to the instrument by model number
and serial number. On receipt of the information,
you will be informed of shipping instructions. If
requested, an estimate of the charges will be made
before work begins, provided the instrument is
not covered by the warranty.
SHIPPING
The unit employs а meter movement which,
though electrically rugged, should be protected
from mechanical shock. Therefore, the instru-
ment should be surrounded by three inches of
excelsior or similar absorbing material and then
packed іп а strong exterior container. It should
be shipped via truck, railway express, air freight,
or air express. Тһе instrument should not be
handled roughly during packing.

WARRANTY
This Motorola instrument is guaranteed by
Motorola for a period of one year after delivery
tothe original purchaser against defects in design,
material, and workmanship. Our liability under
this warranty is limited to servicing or adjusting
anyinstrument returned tothe factory Service De-
partment for that purpose and to replace any de-
fective parts thereof.
This warranty is effective for one year after
delivery to the original purchaser when the in-
strument is returned, transportation charges pre-
paid by the original purchaser, and when upon
our examination it is disclosed to our satisfaction
to be defective. If the fault has been caused Бу
misuse or abnormal conditions of operation, re-
pairs will be billed at the net price of necessary
parts and а service charge at Motorola's then pre-
vailing labor rate. Іп this case, an estimate will
be submitted before the work is started.
This warranty i in lieu of all other warran-
ties, expressed or іпірПей and all other obliga-
tions or liabilities on Motorola part.
If any fault develops, the following steps should
be taken:
1. | Notify us at the following address:
Motorola Communications & Electronics, Inc.
Parts and Service Department
1301 E. Algonquin Road
Schaumburg, Illinois 60172
Give full details of the difficulty, and include
Upon receipt
of this information, we will give you service data
or shipping instructions.
model number and serial number.
2. Троп receipt of shipping instructions, for-
ward the instrument prepaid to the above address,
or to the authorized repair station indicated on
the instructions. If requested, an estimate of
the charges will be made before the work be-
gins, if the instrument is not covered by the
warranty.

SECTION
Guaranteed Performance Specifications
NiodelChbsrte 2 22%
INTRODUCTION . . .
DESCRIPTION . . . .
Functions , ,
а.
b.
С»
а.
Instrument Characteristics
Construction
o
о
AC Power Supply
METER SCALES, . . ,
CONTROLS AND INPUT TERMINATIONS
a. AC Voltage Scales
bi
Ce
а.
b.
с.
d.
e.
[2
ge
Decibel Scale,
Battery Condition Scale
Range Selector Switch ,
OFF-B+ CHK, -METER-OUTPUT
OFF-B+ CHK, METER-OUTPUT
Input Terminations.
Output Termination,
Test Lead Accessory ,
230/117 Volt Adapter Cable
CIRCUIT DESCRIPTION
Input attenuation.
Pre-Amplifier
Amplifier. .
Output Stage .
а.
or
с.
d.
e
f
Meter Circuit
Power Supply (S1053C Only)
OPERATION . . . .
Mechanical Meter Zero
Operation from an AC Source
Operation from Internal Battery
а.
b.
Co
d.
e.
"e
p
h.
AC Voltage Measurement
о
Power Measurements .
Examples of AC Voltage and Power
Amplifier Operation
Battery Conservation
TEMPERATURE EFFECTS
APPLICATIONS . .
CALIBRATION AND MAINTENANCE
SCHEMATIC DIAGRAMS AND PARTS LIST
а.
b.
с.
а.
Dis
с.
а.
b.
General а
Voltmeter.
Amplifier .
General =
Calibration
.
Troubleshooting .
Model $1051C
Model 51053С
.
.
ө
о
Functions
CONTENTS
° ° . . .
. . . . .
. o . . °
. e о . .
. . o . .
. . . о .
. . e . .
. е о . е
. ° ° ° °
. . . . .
. . ° ° °
° ° . . .
О . о . .
. . o
Functions
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STILO MON 6
КИ | ORC
Me hy те, Ж ыс
TER E ET,
Measurements
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ас S -
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ch ко .
Se Ame e
Switch (Model S1051C),
Switch (Model 51053С),
PAGE
ii
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15
16

1. INTRODUCTION
The Motorola Transistorized AC Voltmeters
offer many advantages not found in a-c vacuum
tube voltmeters. Small physical size, light
weight and full transistorization permit com-
plete portability for field use. Тһе absence
of heat producing elements, such as tubes and
transformers, lessens the need for frequent re-
calibration and increases component life, The
.Model S1051C.is battery operated. The Model
„ 51053С, in addition to being battery operated, con-
tains an a-c power supply which operates froma
117уа-с, 50-400 срв source. A detachable power
cord is supplied with the Model 51053С. Тһе
SKN6009A 230/117 Volt Adpater Cable Kit (an op-
tional item not furnished with the standard Model
$1053C) permits operation from а 230 volt, 50-
400 cps power source.
2. DESCRIPTION
а. Functions
These transistorized a-c voltmeters are ca-
pable of accurately performing the following func-
tions:
(1) AC voltage measurement from 0.1 milli-
volt to 300 volts in а frequency range of20 cycles
per second to 1 megacycle.
(2) Power measurements from -72 to +52
dbm when measured across 600 ohm impedance
(0 dbm - 1 milliwatt into 600 ohms).
(3) Comparative power measurements from
-72 to +52 db (when measured at the same imped-
ance level).
(4) High gain isolation amplifier with high
input resistance and low impedance output for amp-
lification of low level audio or r-f signals.
b. Instrument Characteristics
This instrument is similar to many other a-c
voltmeters in that the meter movement responds
to average values of applied voltages. The meter
Scale is calibrated to read the rms value of a
sinusoidal waveform. When the input waveform
departs from a pure sine wave, the meter indica-
tion will be in error by the ratio of the average
value to the rms value of the incoming waveform.
(See figures 1 and 2 in paragraph 8.)
c. Construction
Although primarily designed for laboratory
use, these instruments, being self-powered, are
quite suitable for portable use without sacrificing
the accuracy or versatility ofalaboratory instru-
ment. A detachable metal cover protects the front
panel from damage that might occur in portable
use. Clips for storing the meter cable or other
accessories are mounted on the inside of the cov-
er;
d. AC Power Supply
The power supply of the Model 51053С con-
tains a conventional half-wave diode rectifier cir-
cuit with а capacitor input filter connected to the
output. А Zener diode is connected across the
output for voltage regulation. The input step-down
transformer is installed in the line cord circuit
and isolates the instrument case from the a-c
source, Тре ground pin of the line cord is not
connected to the instrument case. Тһе line cord
is detachable when portable operation with an in-
ternal battery is desired.
3. METER SCALES
The meter is calibrated in two linear a-c
voltage scales, a decibel scale anda battery con-
dition scale, It uses а 0-50 microampere taut-
band movement with non-linearity less than 19
of full-scale deflection. Damping is adjusted to
eliminate 'overshoot'' for convenience in reading
the pointer indication. The meter scales and their
applications are as follows:
a. AC Voltage Scales
The two linear scales (black) are used to mea-
sure rms values of a-c voltages, The upper scale
is graduated to a full-scale value of 1.0 and the
lower scale is graduated to a full-scale reading
of 3.2. АП a-c voltages from 0. 1 millivoltto 300
volts rms are read directly from these scales
using the full scale factors appearing onthe range
selector switch positions.
b. Decibel Scale
The DECIBEL scale (red) is used for dbm
measurement when measuring power level into а
600 ohm impedance or comparative db levels when
measured at the same impedance level. The scale

VOLTS ¢
MILLIVOLTS ۾󰾯
A
INPUT
ATTENUATOR
PRE-
AMPLIFIER
SECOND
ATTENUATOR
А OUTPUT
O—]RECTIFIER
OUTPUT
STAGE OUTPUT
AMPLIFIER
BLOCK DIAGRAM
is calibrated from -12 to 42 and readings are ob-
tained by using the algebraic sumofthe range se-
lector switch position and the meter pointer indi-
cation.
c. Battery Condition Scale
Тһе LINE OR BATTERY O.K. scale (red) is
the small scale above and to the rightofthe upper
a-c voltage scale. The meter pointer indication
within the scale limits is а relative indication of
battery condition (under load) or of the a-c power
supply output.
4. CONTROLS AND INPUT TERMINATIONS
All controls and input terminations used for
measurement are located on the front panel ofthe
instrument,
a. Range Selector Switch
This is а 12-position switch used to selectthe
proper voltage or decibel range. Тһе correct
Switch position is determined by the level applied
to the input.
b. OFF-B+ CHK, -METER-OUTPUT
Function Switch (Model S1051C)
This switch permits a check of the internal
battery condition under load in addition to turn-
ing the instrument on or off, The meter is con-
nected to the battery under a simulated load when
the switchis placedinthe B+ CHK, position. Volt-
age measurements may be made in the METER
position. Amplifier output is connected to the
front panel BNC connector in the OUTPUT posi-
tion.
с. OFF-B+CHK,-METER-OUTPUT
Function Switch (Model S1053C)
This is an 8-position (continuous rotation)
switch which performs four functions: OFF, Bt
CHK., METER and OUTPUT (see photograph on
frontispiece of this manual). The markings on
the knob (pointer marks labeled LINE and BATT)
automatically indicate whether the internal bat-
tery or the a-c line is in use as a power source.
METER and OUTPUT functions are the same as
those described in the preceding paragraph.
d. Input Terminations
The units are equipped with two binding posts
that are mounted on a molded polystyrene base se-
lected for its low loss characteristics at high fre-
quencies. These 'six-way''binding posts are used
to make electrical connections with single and
double pin banana type plugs, tipped plugs, spade
lugs, alligator clips and bare wire.
e. Output Termination
The units are equipped with a BNC coaxialre-
ceptacle which is mounted on the front panel. This
receptacle furnishes amplifier output for external
applications when the function selector switch is
in the OUTPUT position.
WARNING
The voltmeters have the GND terminal
connected to the instrument case. Ex-
treme caution should be exercised when
connecting this terminal to off ground
potentials (referenced to ground of the
circuit being measured) to minimize
shock hazard to operating personnel.
When high d-c potentials are present,
connect а large coupling capacitor in
series with this terminal and a l-meg-
ohm resistor between this terminal and
referenced ground of the circuit being
measured.
f. Test Lead Accessory (Optional Accessory)
The SKN6001A Meter Cable Kit is available
as an optional test lead accessory. It is а 30"
shielded cable terminated at one end in a standard
two-pin banana plug. The probe end of the cable
is terminated in two insulated alligator clips.
BEPD-9635-O

gə 230/117 Volt Adapter Cable (Optional
Accessory)
The Model SKN6009A 230/117 Volt Adapter
Cable is an optional accessory, and will provide
а 117 у a-c source for the 51053C Transistorized
AC Voltmeter when it (the adapter)is plugged in-
to а 230 v a-c line. Тһе adapter cable consists
of approximately six feetof 3-conductor cable, a
small cylindrical housing containing a potted step-
down transformer and a 3-ріп connector which
mates with the plug on the a-c voltmeter power
cable. An a-c line plug is not supplied with the
cable due to the lack of standardization of the
types used, When connecting an a-c line plug,
connect the BLK and WHT leads to the 230 volt
line and connect the GRN lead to ground.
h. Battery Installation and Aging
The battery (60B82292H01 or Mallory TR136)
must be installed with the positive end (+)firstas
indicated on the battery plug button.
Uponinstalling a new battery there is approxi-
mately а 5 hour period for the battery to age to
its long term voltage value. During this period
| of time the voltmeter error may be increased by
approximately +1/2% of full scale. If this error
is not tolerable it is suggested that the battery be
pre-aged. This can be accomplished after instal-
lation of à new battery by placing the voltmeter
function switch in the B+ check position for 5
hours.
Т» Needle Kick
Kicking of the needle immediately after the
instrument is turned on is due to charging and/or
discharging of the electrolytic capacitors. The
needle kick can also be noticed especially when
changing the range switch between 300 MV and 1
V ranges, and 1 V and 3 V ranges.
It is suggested that the instrument be turned
on for at least two minutes before using to re-
form the charge on the electrodes of the electro-
lytic capacitors.
5. CIRCUIT DESCRIPTION .
Refer to the block diagram for general infor-
mation and to the schematic diagram for detailed
wiring information.
a. Input Attenuation
Two precision resistor attenuators are used
to reduce the input level. The input attenuator
(used only on ranges above 1 volt) reduces the
input level by 60 db. A second attenuator at the
output of the pre-amplifieris used to accomplish
additional attenuation in 10 db steps. А three
Section potentiometer permits adjustment for
minor loading variations or resistance changes
of the second attenuator.
b. Pre-amplifier
The pre-amplifier presents a high inputim-
pedance necessary to prevent circuitloading and
résultant erroneous readings in many applications,
Transistor Ol is connected in а "bootstrap" con-
figuration. The northallylow input impedance of
transistor amplifiers is increased through the
use of feedback to the high levelrequired for ac-
curate measurement. Two protection diodes
(СВ1 and CR2) are connected in the base circuit
of the input transistor (Ol) to protect the instru-
ment from excessive input voltages. А maximum
of 550 volts peak (sum of the a-c and d-c voltages)
may be applied on any VOLT range without da-
mage to the instrument, Amaximum of 110 volts
rms continuous or 220 volts rms for 10 seconds
or less can be applied on any MILLIVOLT range
without damage.
C Amplifier
The main amplifier consists of 3 pairs of
direct-coupled common emitter stages followed
by an emitter follower output stage. Тһе nega-
tive voltage is fed back from the collector of the
Second stage to the emitter of the first stage in
each direct coupled pair.
The input impedance of the first pair (Q3
and Q4) presents a fixed load for the second at-
tenuator. Theinputimpedance is essentially the
parallel combination of R22 and R23 because the
input impedance of Q3 is raised to а very high
value by the use of negative feedback.
A variable gain control (R36) in the emitter
circuit of Q5 controls the net gain of Q5 and Q6
for calibration purposes. C28 and R48 areused
for high frequency compensation,
In the METER. position of the function selec-
tor switch, the meter and the rectifier circuit
areconnectedinthe negative feedback loop (from
the collector of Q8 to the emitter of Q7). Also
(with the switchinthe METER position), the rear
section of switch 52В disconnects d-c bias from
the base of Q9 and the collector of Q8. When the
function selector switch is in the OUTPUT posi-
tion, R51 and C29 are substituted for the meter

rectifier circuit in the collector circuit of Q8,
and switch S2B applies bias to the base of Q9 by
connecting it to the collector of Q8.
Since the function selector switch іп the OUT-
PUT position disconnects the rectifier meter
circuit, distortion due to the rectifier diodes is
eliminated. Thus, the amplifier output contains
very little distortion,
а. Output Stage
When the collector of Q8 is connected to the
base of Q9 through section S2B of the function se-
lector switch, ап output signal appears at the
emitter of the N-P-N transistor 09. This signal
is coupled to the output connector on the front
panel through C31, a 100 uuf capacitor and a
shielded cable. The output impedance of the amp-
lifier is approximately 50 ohms,
e. Meter Circuit
The output of Q8 is applied to a full wave
bridge rectifier consisting of two high frequency
diodes (СКЗ and Ска). A 0-50 microampere
taut-band meter movement (М1) is connected a-
cross the output of the rectifierto measure the re-
sultant d-c current. Signal current from the
meter circuit is fed back to the amplifier to ob-
tain gain stability and meter linearity over the
entire bandwidth.
fe Power Supply (S1053C Only)
The Model S1053C AC Voltmeter may be
powered from either an internal battery or from
the rectifier circuit which operates from the a-c
line. The rectifier power supply consists of
transformer ТІ and diode rectifier CR5. Filtering
is accomplished by means of the filter network
circuit C32,C33 and R55. Zener diode CR6 pro-
vides voltage regulation. Transformer Tl is
built into the large cylindrical plug РІ which is
plugged into the a~c line; a cable from РІ carries
low voltage secondary current and is terminated
at the other end by P2 which plugs into J1 on the
case of the instrument.
6. OPERATION
a. Mechanical Meter Zero
A screwdriver adjustment is used to mech-
anically zero the meter. It is located on the
meter cover. If the meter pointer does not rest
directly in line withthe Oline of the voltage scales
when the power switch is in the OFF position
(instrument uprighton feet), turn this adjustment
left or right until the pointer is directly in line
with the 0 line.
b. Operation from an AC Source (Model S1053C)
(1) Connect the female plug end of the power
cable to the receptacle at the rear of the instru-
ment case.
(2) Connect the male plug end of the power
cable to a 117 v a-c (50-400 cps) receptacle. A
230 v a-c power source may be reduced to the
required 117 v a-c with the Model SKN60094A 230/
117 VAC Adapter Cable Kit.
(3) Placethe LINE side ofthe function switch
in the B+ CHK. position and check the power sup-
ply output by observing the reading on the LINE
OR BATTERY O.K. scale.
(4). Rotate the LINE side of the function
switch to the METER position for voltage mea-
surements or to the OUTPUT position for amp-
lifier applications. |
МОТЕ
Should sensitive measurements require
complete isolation from r-f energy
which may be present on the a-c line,
switch the Model S1053C to battery
operation and remove the power cable
from the instrument housing.
с. Operation From Internal Battery
Place the function switch in the B+ СНК, po-
sition, A new battery will give ameter indication
near the upper limits of the LINE OR BATTERY
О.К, scale. After a few hours of operation, the
meter indication will be approximately mid-scale.
If the meter indication just reaches or falls below
the lower limits of the scale, the accuracy of the
instrument will be affected and the battery must
be replaced, Refer to the MAINTENANCE para-
graph of this manual for detailed replacement in-
formation.
d. AC Voltage Measurement
(1) Place the function switch in the ON po-
sition.
(2) A rapid check of the condition of the in-
strument may be performed by placing the range
selector switch in the 1 MILLIVOLT position.
The meter indication should be anywhere from
0.1 to fullor off-scale deflection depending on
the proximity of stray electric fields from a-c
power lines.

(3) Place the range selector switch ina
VOLTS or MILLIVOLTS position corresponding
to an expected meter indication in the upper 2/3
of the meter scale. Readings in this portion of
the scale are most nearly accurate and ranges
should be selected to accomplish this whenever
possible.
NOTE
When in doubt as to expected voltage
levels, good practice is to place the
range selector switchinthe least sen-
sitive (highest voltage) range and pre-
gressively increase the sensitivity
(switch to lower voltage ranges) until
а reading in the upper 2/3 of the scale
is obtained. Note alsothatinthe METER
position, the amplifier output is dis-
abled.
(4) Connect the input terminals across the
voltage source to be measured.
WARNING
These voltmeters have the GND ter-
minal connected to the instrument
case, Extreme caution should be ex-
ercised when connecting this terminal
to off ground potentials (referenced
to ground of the circuit being measured)
to minimize shock hazardto operating
personnel. When high d-c potentials
are present, connect a 1 megohm re-
sistor between this terminal and re-
ferenced ground to the circuit being
measured, and bypass this resistor
witha high voltage capacitor ofavalue
of .22 ufd or larger.
e. Power Measurements
Power measurements in terms of db or dbm
are made inthe same manner as a-c voltage mea-
TABLE 1
Range Selector Meter
Switch Position Scale Indication Level
300 VOLTS
10 VOLTS
3 MILLIVOLTS
0-3.2
0-1.0
0-3.2
0-1.0
DECIBEL
DECIBEL
DECIBEL
DECIBEL
1 MILLIVOLTS
+50 DECIBELS
+20 DECIBELS
-60 DECIBELS
-40 DECIBELS
surements exceptthatthe meter indication is read
fromthe DECIBEL scale, When making measure-
ments in terms of dbm, the measurements must
be made across a 600 ohm impedance (0 dbm - 1
milliwatt into 600 ohms). Comparative power
level measurements in terms of db may be made
by noting the difference in db readings obtained
when each measurement is made across the same
value of impedance. Тһе correct level іп db or
dbm is the algebraic sum of the meter indication
on the DECIBEL scale and the range selector
switch DECIBEL position.
f. Examplesof AC Voltage and Power Measure-
ments
Hd
o
The following tablelists a number of meter
indications andtheir respective voltage and power
levels.
210 volts a-c rms
6.4 volts a-c rms
0.0026 volts a-c rms
0.00072 volts a-c rms
+51 decibels
+15 decibels
-68 decibels
-38 decibels
р. Amplifier Operation
(1) Place the function switch in the METER
position. (In the Model S1053C voltmeter, there
аге two markings--LINE and ВАТТ--оце of which
should be turned to the METER position, depend-
ing upon whether the meter is powered from the
a-c line or from the internal battery.)
(2) Place the range selector switch in a
VOLTS or MILLIVOLTS position such thatthe ex-
pected meter indication will register inthe upper
2/3 of the meter scale. The output voltage ofthe
amplifier will depend on this setting, and will be
approximately 0.5 volt (rms) for a full scale me-
ter reading and 0.25 volt (rms) at half scale de-
flection, Be sure to make this voltage measure-
ment if the input voltage is not known, Ап ехсе5-
sive overload input signal can damage the instru-
ment. See the overload protection limits in Table
of Guaranteed Performance Specifications.

(3) Place the function switchinthe OUTPUT
position; this will disconnect the meter circuitry
and provide an amplified output signal. Whenthe
function switch is in the OUTPUT position, bat-
tery drain is increased by approximately 40% (or
1.2 ma). (Although the OUTPUT position of the
function switch disconnects the rectifier circuit
to eliminate distortion which would be caused by
the rectifier diodes, the meter may show some
deflection at higher frequencies due to capacitive
coupling of the switches, Тһе meter may deflect
either above or below zero if the amplifier is
connected to a noisy source or is overdriven.)
NOTE
Minimum loading to be used with the
amplifier must be not less than 600
ohms resistive and/or not morethan
200 uuf capacitive load. The output
cable may be RG-58A/U, RG-59/U,
or other r-f cable fitted with a female
RG-59/U cable have a capacity of
approximately 24 uuf per foot;
avoid using long cable at the out-
put.
(4) Output voltage can Бе attenuated in 10 db
steps by turning the range selector switch to the
next higher range. Example: If the input is 1 mv
and the range selector switch is in the 1 MILLI-
VOLT position, output will be „5 volts rms, an
approximate voltage gain of 54 db. То attenuate
the output 10 db, turn the range selector switch
to the 3 MILLIVOLT setting; the output will then
be 0.157 volts rms. ТЕ another 10 db attenuation
is required, turnthe range selector switch to the
10 MILLIVOLT position. The corresponding out-
put voltage will be 0.05 volts rms.
Voltage gain for any range switch posi-
tion up to 300 MILLIVOLTS is given by the rela-
tion:
Voltage gain -
0.5 volts rms
Full scale value of range setting
or: Voltage gain (db)=
BO log 0.5 volts rms
Full scale value of range setting
The amplifier consists of 3common col-
lector (emitter follower) stages and 6 common
emitter stages.. The common collector (emitter
follower) stages will not reverse phase. The 6
common emitter stages will each provide а 180°
phase shift which results in 6 x 180? or 3 x 360?
phase shift; hence, input and output voltages are
"1
in the same phase, Theoretically at mid frequen-
cies there will be no phase shift due to reactive
characteristics of the circuit and components,
although such phase shift may be present at very
high or very low frequencies. Тһе exact amount
of such phase shift cannot be guaranteed.
h. Battery Conservation
Whenthe instrumentis operated by the inter-
nal battery, it should be turned off when not in
use to prolong battery life. Accuracy willnot be
affected by using the instrument immediately after
turning it on asthere is essentially no ''warm-up"
period required, If the instrument has not been
used for extended periods (6 weeks or longer) а
five minute stabilization period is recommended
before use.
7. TEMPERATURE EFFECTS
As with most precision measuring equipment
this instrument has certaintemperature limitations,
Accurate readings are obtained in normal temper-
atures. Avoid operation and storage іп tempera-
tures above 50°С (122? Е). Storage in tempera-
tures less than -40°C or - 409 F should also be avoid-
ed. Тһе following table will provide an idea ofthe
accuracy of the instrument (except for the 300 volt
range) as influenced by temperature.
TABLE II
Full Scale
Temperature | Accuracy Frequency
20°C to 30°С]. 23%
300 kc to 1 mc
30*C to 40
20°C to -0° C| 44h, -54| 20 ера to 300 kc |
40°C to 50°C | 159, -6% 300 kc to 1 mc
8. APPLICATIONS
Qo tor 2057
(ue
a. General
A complete understanding of instrument ca-
pabilites and effects on various circuits is nec-
essary to obtain optimum accuracy in difficult
measurements, This instrument measures aver-
age voltage levels of sinusoidal waveforms and
the meter scale is calibrated in rms levels. The
meter reading may be in error when the instru-
ment is used to measure other than sinusoidal
voltage waveforms. Тһе instrument will accept
voltage peaks up totwice the rms value of the in-
put at full scale deflection without waveform clip-
ping.

BEPD-4997-A
BEPD-4998-A
AC VOLTMETER RESPONSE TO 2ND HARMONIC
110
ЕЕГ
0
5 0—1 415. 20 25
PERCENTAGE ОҒ 2ND HARMONIC CONTENT
METER READINGS MAY VARY BETWEEN
UPPER AND LOWER LIMITS DEPENDING
ON PHASE RELATIONSHIP OF FUNDAMENTAL
AND HARMONIC.
NOTE:
RESPONSE PERCENTAGE AS COMPARED TO FUNDAMENTAL
FIGURE 1.
The curves of figures 1 and2illustrate some
of the effects of the harmonic content of non-
sinusoidal waveforms on meter readings. It can
be noted from these curves that the meter willal-
ways read lower than the true rms value when
measuring waveforms having a second harmonic
content, The meter may read higher or lower than
the true rms value when measuring waveforms
having а third harmonic content.
b. Voltmeter
А brief outline of typical applications for the
a-c voltmeter is included to show the versatility
of an instrument of this type. Unique uses for this
instrument will be found as capabilities become
more evident.
D ric requency Measurements
Low level audio voltages generated in
piezo-electric and magnetostrictive electromech-
anical devices (phonograph cartridges, tape re-
cording and playback heads, and microphones) may
be accurately measured on the lower rangesof
the meter.
Voltage levels in audio and ultra-sonic
amplifiers using either electron tubes or tran-
sistors may also be measured without disrupting
the circuit under test.
Output voltages from power amplifiers,
such as P, A, loudspeaker systems, may be mea-
sured across low impedance speakers and high
impedance distribution lines without any loss of
accuracy of the measuring instrument. However,
ШЕ ЕЕЕ
” UPPER
LIMIT
LAT 5
35
AC VOLTMETER RESPONSE TO 3RD HARMONIC
ШИТ,
115
110
105
95
RESPONSE PERCENTAGE AS COMPARED TO FUNDAMENTAL
0 5 40 15 20 25 ЗО 35
PERCENTAGE ОҒ 3RD HARMONIC CONTENT
NOTE: METER READINGS MAY VARY BETWEEN
UPPER AND LOWER LIMITS DEPENDING
ON PHASE RELATIONSHIP OF FUNDAMENTAL
AND HARMONIC.
FIGURE 2.
do
not
exceed
the
maximum
overload
voltages
as
specified
in
the
GUARANT
EED
PERFORMANCE
SPECIFICATIONS
chart
included
in
this
manual.
Hum levels of power supplies may also be
measured. When d-c voltages in excess of the
instrument rating (550 volts-sum ofthe a-c peak
and d-c) are present, a 0.1 microfaradcapaci-
tor should be connected in series withthe INPUT
terminal and а 10 megohm resistor connected be-
tween the INPUT and GND terminals. Use a ca-
pacitor with a higher d-c voltage ratingthanthat
of the power supply being measured.
The а-с voltmeter will accurately mea-
sure voltagelevelsini-fand r-f amplifiers, mix-
ers, detectors, oscillators and modulators using
either electron tubes or transistors. Measure-
ments at these higher frequencies should be per-
formed using very short direct leads betweenthe
voltmeter and the circuit under test. This will
avoid the capacitive shunting effects which are
inherent in shielded cables and long test leads.

The input resistance and shunt capacity
of the instrument must be considered when mea-
suring voltages at radio frequencies. Тре loading
effect is most predominant on high impedance
tube circuits (especially on tuned circuits). The
influence is considerably less on low impedance
transistor circuits, where the shunt capacity of
the instrument is normally а small part of the
tuning circuit being measured.
With battery operation, the instruments
are very useful as null indicators, sincethey are
isolated from the a-c line.
NOTE
To completely isolate the S1053C Volt-
meter from the a-c line and eliminate
a-c pickup, remove the power cable
plug from the rear of the unit.
WARNING
Place the voltmeter as far as possible
from high power r-f transmitters to
avoid possible r-f pick-up through the
voltmeter aluminum housing.
The high sensitivity and low internal
noise allows an accurate balance of the bridge
circuit to be made. Due to the wide frequency
response of the instrument, it is important that
the oscillator supplying the bridge be completely
free from harmonics.
c. Amplifier
Included in applications of the 51051С or
51053С equipmentas an audio or radio frequency
amplifiers are the following:
The instruments may be used as high gain
pre-amplifiers for the amplification of low level
audio voltages generated in piezo-electric and
magnetostrictive electromechanical devices (pho-
,nograph cartridges, tape equipment heads, and
microphones).
They may be used to amplify low signal level
voltages generated by audio or r-f oscillators in
order to drive frequency counters,
They may be used as isolation amplifiers
with high input resistance and low impedance
outputs. Тһе input resistance is greater than 1
megohm in the MILLIVOLT position and greater
than 10 megohms in the VOLTS position.
9. CALIBRATION AND MAINTENANCE
a. General
Accuracy of the S1051C and 51053С Ттап-
sistorized AC Voltmeters can be maintained by
periodic calibration of the instruments. Calibra-
tion should be accomplished only by qualified per-
sonnel having adequate test facilities. If desir-
ed, the Model 51051С or S1053C may be returned
to the factory for calibration; refer to the Fore-
word for detailed information on shipment of the
instruments.
The calibration procedure outlined herein
may be used for recalibration of the instrument.
However, if there have been any electrical com-
ponent changes made such as replacement of
diodes, transistors ог range switch assembly, it
is suggested that the instrument be returned to
the factory for calibration,
Table III lists the testinstruments required
for calibration and maintenance of transistorized
a-c voltmeters.
The voltmeter chassis may be removed from
the case by loosening four screws at the back of
the unit, In the a-c powered unit (Model S1053C),
first unplug the power cord from the unit.
b. Calibration
(1) Neise Test
Cover the voltmeter input terminals with
а. shielded double banana plug across whichis con-
nected à 100K ohm resistor. Set the voltmeter
range selector switch tol MILLIVOLT. Theme-
ter indication should be less than 0.1 on the top
(0-1) meter scale.
(2) Needle Kick
(a) After the voltmeter has been "оп!
for at least two minutes, turnthe range selector
switch from the 1 VOLT positiononto the 3 VOLT
position. Note the needle kick. It should be less
than 2596 of full scale deflection.
(b) Return the range selector switch to
the 1 VOLT position and note the needle kick. It
should be less than 25% of full scale deflection,

TABLE III
Sensitivity
deflection
Voltmeter
Calibrator
Test Oscillator Output voltage:
nal oscillator
General Purpose
Oscillator
(low output
impedance):
(3) Input Resistance
(a) Connectthe voltage calibrator to the
input of the voltmeter.
(b) Set the voltage calibrator to 100 mv
at 400 cps and adjust the calibrator gain control
for a full scale reading on the voltmeter 100
MILLIVOLT range.
(c) Insert a parallel combination of a
1 megohm (film) resistor and a 30 uuf capacitor
in series withthe voltmeter input. The new volt-
meter reading should be 1/2 full scale or more
for normal input resistance (1 megohm or great-
er).
Кеану Test
(a) Turn the voltmeter OFF and place
it upright on its feet. Set the meter indicator to
zero with a screwdriver. Turn the voltmeter
Hon".
(b) Connect the voltage calibrator out-
put to the voltmeter input terminals. Set the
calibrator for 1 volt at 400 cps.
` Recommended
Instrument Type Minimum Required Specifications Instrument |
DC Multimeter Sensitivity: 0.1 volt minimum for full scale de-
flection
Accuracy:
+3% of full scale or better
1 millivolt minimum for full scale
AC Voltmeter nsitivity: illi ini
Impedance: 1 megohm or higher
Accuracy: +3% of full scale or better
Accuracy: +0, 259 or better
Voltage Range: 1 mv,3 mv, 10 mv; 100 volts,
300 volts, rms
li mv, 3. тау, 10 тау; --- 3 volte;
into 50 ohms
Monitor Meter сс +0.5% from 10 cps
to 1 mc
Other Features: Provision for use with exter-
Frequency Range: 5 cps to 600 kc
Output: 3 volts min, into 50 ohms
Distortion: 0.5% max, below 500 kc
..
..
Motorola DC Multimeter
or equivalent
Motorola Transistorized
AC Voltmeter
Hewlett- Packard
Model 738AR
Voltmeter- Calibrator
or equivalent
Hewlett- Packard
Model 739AR Frequency
Response Test Set or
equivalent
Hewlett- Packard
Model 200SR Oscillator
or equivalent
(c) Loosenthelocknut on the GAIN con-
trol and adjust the control for full scale indication
(1.0 volt) with the range selector switch in the l
VOLT position. Ifthis adjustment cannot be made,
a malfunction exists in the voltmeter circuits, Do
not continue with the test procedure until the
trouble has beencorrected. Refertothe Trouble-
shooting paragraphinthis manual for instructions.
(d) Adjust the calibrator and check the
voltmeter readings for inputs of 1.0 v, 0.8 v,
0.6 у, 0:4 у and 0.2. v.
(e) Place the voltmeter range selector
Switch in the 3 VOLT position. Adjust the cal-
ibrator and check the readings for inputs of 3.0 v,
Воо Юте 0v, апа 0.5 у.
(5) 400 CPS Calibration
(а) Place the voltmeter in the normal
position and reset the zero, ifnecessary, while
the voltmeter is OFF.
(b) Place the range' ‘selector switch in
the
1
MILLIVOLT
position.
338
3/AH
232ИАНО
-30A8 ZIHT ИО
T3iH?
30221
33e

10
CHANGES
HAVE
BEEN
MADE
CAUTION
ON
THIS
PAGE.
SEE
ISSUE
SHEFTX
2
N
Chassis Adjustments Detail
Chassis Adjustments Detail
AEPD-9815-0(CE2286-W21)
AEPD-9819-O(CE2286- X21)
BE. "ини

(c) Connect the voltage calibrator out-
put to the voltmeter input with low-loss, shield-
ed cable (RG-58/U, RG-59/U or equivalent) less
than three feet in length.
(d) . Set the calibrator output of 0.001
volt at 400 cps.
(e) Adjust the voltmeter GAIN control
for a meter reading of 1.0 on the top scale.
(f) Secure thelocknut on the GAIN con-
trols
(g) Check the meter reading to be sure
it still indicates 1.0 on the top scale. If not,
loosen the locknut and repeat steps (d), (e) and
(f).
NOTE
This is à basic adjustment upon which
all others depend. It must be correct.
(h) Set the voltage calibrator and volt-
meter range selector switch accordingto Table
IV. Adjust the corresponding control for full-
scale indication. These steps must be followed
in order, namely, 100 mv first, then 10 mv,
then 3 mv.
TABLE IV
Voltmeter
Voltage
Calibrator
Setting
Adjust for
Range Full-Scale
Position Indication
100 MILLIVOLTS |100 MV Control
B |
0.01 Volt 10 MILLIVOLTS 10 MV Control
0.003 Volt 3 MILLIVOLTS 3 MV Control
(i) Repeat step (h) once or twice until
no further adjustments are necessary.
0.1 Volt
(j Turn the voltmeter range selector
switch to 1 VOLT,
(к) Set the voltage calibrator to 1.0
volt.
(1) Adjust the 1 V, 400cps control (R3)
for full scale indication. This completes the 400
cps calibration.
(m) The accuracy of all other voltage
ranges may be checked in à similar manner by
using the voltage calibrator.
(n) Disconnect the voltage calibrator
from the voltmeter.
(6) 1.0 MC Adjustment
(а) Set the controls on the frequency
response generator (FRG) and the associated
signal generator for an output of approximately
0.001 volt at 400 cps.
(b) Turn the voltmeter range selector
to 1 MILLIVOLT.
(c) Connect the special output cable of
the FRG to the voltmeter input terminals.
(d) Adjust the AMPLITUDE control of
the signal generator until the voltmeter indicates
0.9 on the top scale.
(e) Use the FRG METER SET control
to adjust the FRG meter indicator to one of the
calibrating marks.
(f) Setthe FRG to 1 mc (this will cause
the FRG meter indicator to shift). Reset the me-
ter indicator, with the amplitude control, to the
same calibrating mark used in step (e).
(е) Turn the voltmeter Н. F, TRIMMER
(C28) for а meter indication of 0.9 on the top
scale.
(h) Set the signal generator to 300 kc
and adjust the signal generator AMPLITUDE
control for the same calibrating mark used in
step (е). Note the voltmeter reading.
(i) If the voltmeter reading of step (h)
is higherthanthe reading taken at 1 mc (by more
than 1/2 9), turn the trimmer potentiometer (R48)
counterclockwise about 20?,
(j Repeat steps (f) and (g).
(k) Repeat Step (h). If the voltmeter
reading is still higher than the 1 mc reading (by
more than 1/296), repeat step (i) and then steps
(f) and (g) until the 300 kc reading is within 1/296
of the 1 mc reading.
NOTE
If the voltmeter reading is low at 300
kc in step (1), turnthetrimmer poten-
tiometer clockwise, thén proceed to
steps (f), (g) (h), and (k).
11

SIA
R16 R15
JU1
-63
C2
C1
RANGE SWITCH ASSEMBLY
(FRONT)
CR6
C32
C33
R55
CR5
73 J4 C26 СІЗ
POWER
SUPPLY
BOARD
12
C9 + SIB
RANGE SWITCH ASSEMBLY
(REAR)
C19. CIS C20 RIO OG ӨБ Cl (040 соз
MAIN CIRCUIT BOARD
Component Location Details
CRI
C6
CR2
C4
AEPD-9818-O(CE2286- Z21)
А Та ТТ сон ич pu ma30 /.
ASSA
AEPD-9816-O(CE2286- Y21)