HP 400E Service manual

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MODEL 400E/EL
AC VOLTMETER
Serials Prefixed: 532, 536
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PRELIMINARY
OPERATING AND SERVICE MANUAL
MODEL 400E/EL
AC VOLTMETER
Serials Prefixed: 532, 536
Copyright Hewlett-Packard Company 1965
P.O. Box 301, Loveland, Colorado, 80537 U.S.A.

Model
Sectio
I
Sectio
II
Sectio
Til
Sectio
IV
Sectio
400E/EL
Table
of
Contents
TABLE OF CONTENTS
n Page
GENERAL
INFORMATION
.......-62
2-2
ee
ee
eevee
1-1
Je.
“DESETIPLION.
“ee
aos
iS.
eS
,
wo
eA
LS.
BSE
ee
wR
1-1
1-4.
Instrument
and
Manual
Identification
............
1-1
n
Page
INSTALLATION
|.)
dase
6
od.
BSS
Bre
YR
RO
ww
aes
2-1
Dat.
ANEPOOMCHON:
<<
a
&
Swi
Gee
ee
Se
Se
Se
Se
ae
Se
2-1
2-3.
Initial
Inspection.
.: «6
2
6
&
heh
ee
eG
2-1
2-5.
Power
Requirements
...
2...
2.
ee
tee
eee
ee
es
2-1
2-7.
Grounding
Requirements
........-2+4
eee
eee
2-1
2210.
Installation.
cS)
e-
se
se
Be
a
Be
sh
Se
Sis
we
ee
ay
2-1
2-12
Bench
Mounting
«206
se ee
ee
6
wee
ew
ee
2-1
2-14.
Rack
Mounting:
=.
©
3)
heise
sai
bs
ew
we
SEE
Rs
2-2
2-16.
Combination
Mounting
.........+4-+
252
eee
2-2
2-18.
Repackaging
for
Shipment
.....
2...
2+
ee
eeeee
2-2
n Page
OPERATING
INSTRUCTIONS
.......6+2-0+60022ee88
8-8
3-1
S23.
Introduction:
-3-
4G.
6
4
Bo
a
atte
ewes!
W
wee
2
3-1
3-4.
Location
of
Controls
and
Indicators
............
3-1
3-6. Operating Instructions ...... 2.2. eee ee ee eee 3-1
3-7.
Standard
400
B/E
DL.
-x.4.
©
s
«Sok
Gow
&
Nee
A
ae
6
3-1
3-12.
A400B
with
Option
01.
.
2.4
6.8
eee
ee
es
3-5
3-14. 400E/EL with Option02 ..........-+.00086- 3-7
3-17. 400E/EL with Option03 ..........6.220868- 3-7
n Page
THEORY OF OPERATION | “ics-a° dy 9 Gy eeceoee use. ee Se mee 4-1
AQT.
(General
io
a>
0
Ae
ae
ea
Fee
Be
a
OS
ee
es
4-1
4-6. Input Attenuator (See Schematic, Figure 6-1) ..... 4-1
4-8. Impedance Converter ... 1... ee ee eee eevee 4-1
4-11. Metér Amplifier o5-c-6:. 4 4% BeOS SE ER ee Soars 4-2
4-14. Meter Bridvte: tase go OS ee ee, oe A 4-2
4-17. AC Output-Citcult: <0 s9-e eve 68 See eee ee eG 4-2
4-19.
Power
Supply:
wx.
6-
e658
Gis:
Be
ea
ae,
SE
4-2
n Page
MAINTENANCE: so-55-3. 4.4 2 eck oe ed Be ee oe ee we 5-1
Ba 1s \ Int¥Oduetion® y.6..x se S.4ivea 8 OS Gow hel Ge Ae oe? he as 5-1
5-3. Required Equipment ..... 2... eee eee ee eens 5-1
5-5. Mechanical Zero Adjust (400E Only) ............ 5-1
5-7,.
Performance
Checks
«2.606
«6
6
Riek
ke
koe
Be
ae
eG
5-1
5-9. Accuracy and Frequency Response Test ....... 5-1
5-19. Input Impedance Check ...........2.2.20808. 5-8
5-24. Alignment and Calibration Procedure ........... 5-9
5-26. Cover Removal sé 2-4 eG Se Se OK A AO RES 5-9
ili

Table of Contents
TABLE OF CONTENTS (Cont'd)
Section
V MAINTENANCE (Cont'd)
5-29. Bias’AQist. .. 2 a8 2060s a5: 4 ecm eS
5-31. AC Output Zero ..........-..
5-33. CaliDFation: 2:4.°45.4 06 +5. } ake Sea wee
5-36. Troubleshooting ............4..-.
5-40. Power Supply 2.4: 4.40 44% 4 ees
5-42. Amplifiers «<6 4.494. ee 3 el oud %
5-45. AC Output Circuit) ob eo me Pa ey
Section
VI CIRCUIT DIAGRAMS ............e8.+e-.
6-1. Introduction ..............0e8e8-4
Section
VII REPLACEABLE PARTS .............
7-1. Imtroduction ..........6+4-+e5+80848-8
7-4. Ordering Information ............
7-6. Non-Listed Parts .............-.
Model 400E/EL

models
OE/400EL
AC VOLTMETERS ..
PACKARD
TECHNICAL DATA 12 AUG 65
li
fT
‘Ap
&
EWLETT |
goot AC voLTMeTet :
ci) peer PACKARD 9
“INDIVIDUALLY
~TAUT B
‘ SOLID. STATE.
i P. O. Box 301, Loveland, Colorado, 80537, Tel. [phone]
® Europe: 54 Route Des Acacias, Geneva, Switzerland, Cable: “HEWPACKSA" Tel. [phone]

Page 2
DESCRIPTION
The @ 400E/EL Solid-State AC Voltmeters are ruggedly
built solid-state precision instruments for measuring ac
voltages from 1 millivolt to 300 v rms full scale. They
cover a frequency range from 10 cps to 10 mc and have
constant 10 megohm input resistance on all ranges. Input
capacity is 24 pf on the 1 mv to 1 volt range and 9 pf on
the 3 vole to 300 volt range. The instruments are simple to
operate and give direct voltage and dbm readings.
These ac voltmeters have exceptional long-term stability
because their calibration is not dependent on active com-
ponent parameters which are subject to aging. The 400E/
EL may also be used as stable, high-gain ac amplifiers or
ac-to-de converters.
The 400E has all the characteristics mentioned above
with 1% of reading accuracy on a 4-1/2” mirror-backed
taut-band meter. The meter scale is individually calibrated
for its particular movement with 100 divisions to give an
added measure of readability.
The 400 EL has all the characteristics above with 1% of
reading accuracy on a linear 12 db logarithmic scale. This
meter is also individually calibrated with 120 divisions and
is ideal for db measurements.
The specifications in the chart on the next page show
these compact, lightweight, solid-state voltmeters will give
premium performance at an economical price.
CIRCUIT DESCRIPTION
The Model 400E/EL AC voltmeters use high-gain am-
plifiers having high stability and wide bandwidth. The
solid-state metering circuit is stabilized by an overall feed-
back loop to provide maximum stability. The impedance
converter circuit also uses a large amount of overall feed-
back. These features ensure a high degree of accuracy in-
dependent of line voltage changes or other external effects.
AC-to-DC CONVERTER
The Models 400E/EL provide a dc output (1 volt dc
for full scale meter deflection) proportional to meter de-
flection which can be used to drive a potentiometer or
galvanometer recorder. This dc output is available at the
rear panel of the instrument which is illustrated in figure
1.
Figure |: External Battery Terminals, DC Recorder
Output Terminals and AC Amplifier Terminals
Model 400E/EL
HIGH GAIN AMPLIFIER
Additionally,
the
400E
and
400EL
provide
a
stable
low
distortion,
high-gain,
wideband
ac
amplifier
with
a
50-ohm
output
impedance.
Frequency
response
is
from
10
cps
to
10
mc.
The
ac
output
is
150
mv
rms
for
full
scale
meter
deflection
on
all
ranges
except
on
the
1
mv
range
which
is
105
mv.
LOGARITHMIC MODEL 400EL
The
@
400EL
is
designed
for
greater
resolution
in
db
measurements.
This
instrument
is
useful
for
acoustical
and
communications
applications.
It
incorporates
an
@
taut-
band
mirror-backed
logarithmic
meter
movement.
For
ut-
most
accuracy,
the
meter
scale
is
individually
calibrated,
using
the
new
@
logarithmic
meter
calibrator,
The
meter
scale
provides
maximum
readability
and
+1%
of
reading
accuracy
on
the
upper
half
of
the
scale
and
+1.5%
of
read-
ing
accuracy
on
the
lower
half
scale.
The
decibel
scale
is
more
than
4-3/8”
long,
and
voltage
scales
spread
across
the
full
length.
A
range
switch
changes
sensitivity
in
10
db
steps
which,
combined
with
the
12
db
scale,
provides
the
overlap
desirable
in
decibel
level
measurements.
EASY TO USE
A
front
panel
range
switch
which
changes
sensitivity
in
10
db
steps,
combined
with
the
db
calibration
of
the
me-
ter,
permits
reading
of
dbm
directly
without
calibration
or
conversion
from
—72
to
+52
dbm
(0
dbm=1
milliwatt
into
600
ohms).
In
addition,
the
10
db
range
spacing
pro-
vides
2
voltage
scales
so
that
readings
are
always
greater
than
one-third
full
scale.
Consequently,
the
highest
possi-
ble
readability
and
accuracy
are
provided.
OPTIONS
Special
db-measuring
option—The
Model
400E
reads
directly
in
volts
and
db,
with
the
voltage
scale
uppermost.
The
Model
400E
(Option
01.)
with
db
scale
uppermost
is
recommended
for
greater
resolution
in
db
measurements.
Refer
to
figure
2.
1 MW 6000
DeciBELS gt a
VOLTS
HEWLETT PACKARD
Figure 2: Meter face on Model 400E (Option O1).

Model 400E/EL Page 3
Relative signal reading option—Available on special
order, the 400E/EL (Option 02.) provides a front-panel
relative measurement control allowing a 3 db reduction in
sensitivity on each calibration range. This feature enables
the user to set the meter to a convenient level (such as 0
db) for relative measurements. The control is detented in
the absolute position to disconnect the relative measuring weciais
circuitry and to ensure calibration accuracy. d tun ena
BEWLETT Gp racanee
Constant Input Capacity Option—Available on special
order, the 400E,EL (Option:03) provides constant input
capacity (28 pf) on all ranges and 10 megohms input
resistance.
y ABSOLUTE.”
Figure
3:
Option
02
(400E
and
EL)
provides
relative
or
absolute
measurements.
SPECIFICATIONS
he
Model
|
te
4008
|
mv
to
300
v
full
scale,
12
ranges
Frequency
range
10
cps
to
10
mc
Calibration reads rms value of sine wave; voltage indication pro-
portional to absolute average value of applied wave;
3 MV to 300 V RANGES
db scale —10 to + 2 db, 10 db between ranges: 100
Frequency 10CPS 20CPS 40CPS 500 KC 2MC
divisions on 0 to | scale.
1MC 4MC 10 MC
AT FULL SCALE
AT 1/3 FULL SCALE
reads rms value of sine wave; voltage indication propor-
tional
to
absolute
average
value
of
applied
wave:
linear|'
db
scale
—10
db
to
+2
db.
10
db
between
ranges:
logarithmic
voltage
scales
0.3
to
|
and
0.8
to
3:
120
divisions from — 10 to +2 db.
HP MODEL 400E
ACCURACY % Of Reading
ACCURACY % Of Reading
1 MY RANGE
Frequency
10CPS
20CPS
40CPS
100
CPS
100
KC
500
KC
2MC
6MC
200 KC 1MC 4MC
AT FULL SCALE
AT 1/3 FULL SCALE
— 10
AT 1/10 FULL SCALE

Page 4
Model 400E/EL
SPECIFICATIONS (Cont.)
HP MODEL 400EL
ACCURACY % Of Reading
3 MV to 300 V RANGES
Frequency 10CPS 20CPS 40CPS
AT FULL SCALE
==]
AT 1/3 FULL SCALE +4, [a2
500 KC 2Mc
IMC 4MC 10 MC
| MV RANGE
Frequency
AT 1/3 FULL SCALE ele
10CPS 20CPS 40CPS
ACCURACY % Of Reading
500 KC 2MC 6 MC
200 KC 1MC 4MC
HP MODELS 400E/EL
AC-to-DC CONVERTER OUTPUT
ACCURACY % Of Reading
10CPS 20CPS 40CPS 100 CPS
3 MV-300 V RANGES
Frequency
AT 1/3 FULL SCALE
| MV RANGE
Frequency
AT FULL SCALE +2 &
AT 1/3 FULL SCALE
10CPS 20CPS 40CPS 100 CPS
“For 15°C - 40°C on 1 mv - 1 volt ranges only
HP MODEL 400E/EL
Input Impedance: 10 megohms shunted by 24 pf on the
1 mv-lv ranges and 10 megohms shunted by 9 pf on
the 3v-300v ranges.
Amplifier AC Output: 150 mv rms for full scale meter
indication; output impedance 50 ohms, 10 cps to 10 mc
(105 mv on the 1 mv range).
AC.DC Converter Output: 1 vdce output for full scale
meter deflection.
Output Resistance: 1000 ohms.
Response Time: 1 second to within 1% of final value
for a step change.
AC Power: 115 or 230 volts +10%, 50 to 1000 cps,
approx. 5 watts.
Temperature Range: 0 to +55°C (except where noted on
accuracy charts).
External Battery Operation:
Terminals are provided on rear panel; positive and nega-
tive voltages between 35v and 55v are required; current
drain from each voltage is approx. 54 ma. (External
switching and on/off monitoring should be used for
battery operation).
a
500 KC 2MC
100 KC 500 KC 2MC 6 MC
200 KC Cc
Weight: Net 6 Ibs. (2,7 kg), Shipping 9 Ibs. (4 kg).
Dimensions: 6-1/2” high, 5-1/8” wide, 11” deep (165,1
x 130,2 x 279,4 mm).
Price:
400E $285.00
A00EL $295.00
Option: 01 (400E only) reads directly in wolts and
db with db scale uppermost. Add $10.00
Option: 02 (400E or 400EL) front panel relative
control. Add $10.00.
Option: 03 (400E or 400EL) Constant Input ca-
pacity (10 megohms shunted by 28 pf) add §25.00
Option: 04 (400E only) includes all three options;
01, 02, and 03. Add $45.00.
Note: When ordering 2 options or less pleae desig-
nate each option.
Prices f.0.b. factory
Data subject to change without notice
& Indicates change from prior specifications
12 \.UG 65

Model 400E/EL . Section I
Paragraphs 1-1 to 1-6
SECTION I
GENERAL INFORMATION
1-1. DESCRIPTION.
1-2. The -hp- Models 400E and 400EL are versatile ac voltmeters and db
meters. Both models can be used as ac to de converters or wideband ampli-
fiers. The Model 400E is primarily intended for voltage measurements,
whereas the Model 400EL is primarily a db meter. However, both meters
indicate both volts anddb. The 400E has a linear ac scale with a logarithmic
db scale underneath, and the 400EL has a linear db scale with a logarithmic
ac scale underneath. Since the difference in scales is the only difference
between the two instruments, this manual will use the term 400E/EL in ref-
erence to both instruments.
1-3. The enclosed data sheet contains a complete description of the 400E/EL
along with a list of specifications.
1-4, INSTRUMENT AND MANUAL IDENTIFICATION.
1-5. Hewlett-Packard instruments are identified by a two-section, eight-
digit
serial
number
(000-00000).
If
the
first
three
digits
of
the
serial
num-
ber
on
your
instrument
do
not
agree
with
those
on
the
title
page
of
this
manual, change sheets supplied with the manual will define differences be-
tween
your
instrument
and
Model
400E/EL
described
in
this
manual.
1-6.
If
the
first
three
digits
of
the
two-section,
eight-digit
serial
number
are prefixed with an E or G, your instrument was produced in Europe. An
E000-00000
serial
number
indicates
that
the
instrument
was
manufactured
in England; a G000-00000 serial number indicates that the instrument was
manufactured in Germany.
1-1

Model
400E/EL
Section
II
Paragraphs
2-1
to
2-13
SECTION I
INSTALLATION
2-1. INTRODUCTION.
2-2.
This
section
contains
informatian
and
instructions
necessary
for
the
installation
and
shipping
of
the
Model
400E
and
400EL
voltmeters.
Included
are
initial
inspection
procedures,
power
and
grounding
requirements,
in-
stallation
information,
and
instructions
for
repackaging
for
shipment.
2-3. INITIAL INSPECTION.
2-4.
This
instrument
was
carefully
inspected
both
mechanically
and
elec-
trically
before
shipment.
It
should
be
physically
free
of
mars
or
scratches
and
in
perfect
electrical
order
upon
receipt.
To
confirm
this,
the
instru-
ment
should
be
inspected
for
physical
damage
in
transit.
Also
check
for
supplied
accessories,
and
test
the
electrical
performance
of
the
instrument
using
the
procedure
outlined
in
Paragraph
5-7.
If
there
is
damage
or
de-
ficiency,
see
the
warranty
on
the
inside
front
cover
of
this
manual.
2-5. POWER REQUIREMENTS.
2-6.
The
Model
400E/EL
can
be
operated
from
any
source
of
115
or
230
volts
at
50
to
1000
cycles
or
from
two
35
to
55
volt
batteries
connected
to
the
rear
panel
BATTERY
terminals.
The
115/230
v
slide
switch
on
the
rear
panel
selects
the
desired
line
voltage.
Power
dissipation
is
5
watts
maximum.
2-7. GROUNDING REQUIREMENTS.
2-8.
To
protect
operating
personnel,
the
National
Electrical
Manufacturers’
Association
(NEMA)
recommends
that
the
instrument
panel
and
cabinet
be
grounded.
All
Hewlett-Packard
instruments
are
equipped
with
a
three-con-
ductor
power
cable
which,
when
plugged
into
an
appropriate
receptacle,
grounds
the
instrument.
The
offset
pin
on
the
power
cable
three-prong
con-
nector
is
the
ground
wire.
2-9.
To
preserve
the
protection
feature
when
operating
the
instrument
from
a
two-contact
outlet,
use
a
three-prong
to
two-prong
adapter
and
connect
the
green pigtail
on the
adapter
to
ground.
2-10. INSTALLATION.
2-11.
The
Model
400E/EL
is
fully
transistorized;
therefore,
no
special
cool-
ing
is
required.
However,
the
instrument
should
not be
operated
where
the
aa
temperature
exceeds
55
C (131
F) or
the
relative
humidity
exceeds
95%.
2-12. BENCH MOUNTING.
2-13.
The
Model
400E/EL
is
shipped
with
plastic
feet
and
tilt
stand
in
place,
ready
for
use as
a
bench
instrument.
2-1

Section II Model 400E/EL
Paragraphs 2-14 to 2-21
2-14. RACK MOUNTING.
2-15. The Model 400E/EL may be rack mounted by using an adapter frame
(-hp- Part No. 5060-0797). The adapter frame is a rack frame that accepts
any combination of submodular units. It can be rack mounted only. For ad-
ditional information, address inquiries to your -hp- Sales and Service Office.
(See Appendix B for office locations. )
2-16. COMBINATION MOUNTING.
2-17. The Model 400E/EL may be mounted in combination with other sub-
modular units by using a Combining Case (-hp- Model 1051A or 1052A). The
Combining Case is a full-module unit which accepts various combinations of
submodular units. Being a full-module unit, it can be bench or rack mounted
and is analogous to any full-module instrument.
2-18. REPACKAGING FOR SHIPMENT.
2-19. The following paragraphs contain a general guide for repackaging of the
instrument for shipment. Refer to Paragraph 2-20 if the original container
is to be used; 2-21 if itis not. If you have any questions, contact your local
-hp- Sales and Service Office. (See Appendix B for office locations. )
NOTE
If the instrument is to be shipped to Hewlett-
Packard for service or repair, attach a tag to
the instrument identifying the owner and indi-
cating the service or repair to be accomplished;
include the model number and full serial number
of the instrument. In any correspondence,
identify the instrument by model number, serial
number, and serial number prefix.
2-20. If original container is to be used, proceed as follows:
a. Place instrument in original container if available. If original
container is not available, one can be purchased from your nearest
-hp- Sales and Service Office.
b. Ensure that container is well sealed with strong tape or metal
bands.
2-21. If original container is not to be used, proceed as follows:
a. Wrap instrument in heavy paper or plastic before placing in an
inner container.
b. Place packing material around all sides of instrument and protet
panel face with cardboard strips.
c. Place instrument and inner container ina heavy carton or wood:n
box and seal with strong tape or metal bands.
d. Mark shipping container with "DELICATE INSTRUMENT",
"FRAGILE" etc.
2-2

Model 400E/EL Section IIT
Paragraphs 3-1 to 3-8
SECTION II
OPERATING INSTRUCTIONS
3-1. INTRODUCTION.
3-2. The Model 400E/EL is primarily an ac voltmeter and db meter, but it
can be used as an ac to de converter or as a wide band amplifier.
3-3. This section explains the controls of the 400E/EL and outlines the
operating procedures for each mode of operation.
3-4. LOCATION OF CONTROLS AND INDICATORS.
3-5. Figure 3-1 shows the location of each of the 400E/EL controls and ex-
plains the function of each.
3-6. OPERATING INSTRUCTIONS.
3-7. STANDARD 400E/EL.
3-8. AC Voltmeter.
NOTE
Since the 400E/EL is average responding and
rms calibrated, any distortion will affect the
accuracy of the measurement. Table 3-1 shows
the errors caused by distortion.
Table 3-1. Effect of Distortion on Average Responding Meter
% Error (*fundamental)
Harmonic % Distortion
Max.
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* Depends on phase relationship between harmonic and fundamental.
a. Ensure that 115-230 vac slide switch on the rear panel matches
line voltage used, and connect power to the instrument. Ensure
that the meter is mechanically zeroed (400E only). See Para-
graph 5-5 for the zero adjustment.
3-1

Section ITI Model 400E/EL
Figure 3-1
400E (OPTION 02)
400E (OPTION Ol) METER FACE
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Figure 3-1. Location of Controls and Indicators
3-2

Model 400E/EL Section DI
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a)
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Figure 3-1 (Cont'd)
400E Scale: Indicates magnitude of applied signal in volts and dbm.
Option
01
places
the
dbm
scale
uppermost
for
greater
resolution.
0
dbm = 1 mw in 600 2.
LINE
Indicator
Lamp:
Indicates
application
of
primary
power.
Line
ON
Toggle
Switch:
Applies
primary
power.
RANGE
Selector:
Selects
full
scale
reading
of
meter.
Dbm
reading
on
scale
adds
algebraically
to
DB
setting
of
RANGE
selector.
REL. REF Adjust (Option 02): Lowers sensitivity of meter by 3 db.
Fully
clockwise
ABSLOUTE
position
retains
full
meter
sensitivity.
This
control
is
used
to
vary
meter
indication
with
a
given
input
in
order
to
make relative readings easier.
AC INPUT: BNC input jack connects signal to be measured.
AOOEL
Scale:
Indicates
magnitude
of
applied
signal
in
volts
and
dbm.
Dbm
scale
is
linear,
and
voltage
scales
are
logarithmic.
This
arrange-
ment
allows
better
resolution
for
db
reading.
0
dbm
=
1
mw
in
600
2.
BATTERY VOLTAGE Terminals: 400E/EL may be powered by connect-
ing two 35 to 55 volt batteries to these terminals.
FUSE: Protects instrument against current overload.
115/230 Volt Slide Switch: Selects 115 or 230 volts ac for line operation.
PRIMARY POWER CONNECTOR: Line voltage is applied through this
connector.
AC OUTPUT: Ac amplifier output. Output impedance is 50 2.
(3) DC OUTPUT: Ac to de converter output. Dc voltage is proportional
to percentage of meter deflection. Output impedance is 1000 Q.
Figure 3-1. Location of Controls and Indicators (Cont'd)
3-3

Section II Model 400E/EL
Paragraph 3-8 (Cont'd)
b. To operate the Model 400E/EL with battery power, connect two
35 to 55 volt batteries as shown in Figure 3-2. Since the front
panel LINE switch has no effect during battery operation, the
DPST switch in Figure 3-2 can be used as a convenient method of
disconnecting the batteries when the instrument is not in use.
BATTERY VOLTAGE
+ _
35-55 Ae 35-95
(35-55v) (35-55v)
400E/EL-B-046)
Figure 3-2. External Battery Connection
c. Turn line ON toggle switch to up position. LINE lamp will glow.
d. Select approximate range of signal to be measured.
DO NOT APPLY MORE THAN 600 VOLTS TO
INPUT. DO NOT OVERLOAD THE 0.001
THROUGH 1 VOLT RANGES WITH MORE THAN
300 VOLTS AT FREQUENCIES BELOW 300 KC
OR WITH MORE THAN 64 VOLTS AT FRE-
QUENCIES ABOVE 300 KC. IF ANY OF THESE
OVERLOADS ARE EXCEEDED, THE INSTRU-
MENT MAY BE DAMAGED.
e. Connect signal to be measured to INPUT terminals, and read the
rms voltage on the scale.
3-4

Model 400E/EL Section ITI
Paragraphs 3-9 to 3-13
3-9. DB Meter.
a.
To make a db or dbm measurement, follow steps a through e in
Paragraph 3-8, and add the scale reading to the RANGE setting.
For example: If the scale reading is +1.5 and the RANGE is -30
db, the final measurement is -28.5 db.
The 400E/EL db scale is calibrated indbm. 0 dbm is equivalent
to 1 milliwatt dissipated by a 600 ohm load. Consequently, any
dbm measurements must be made across a total impedance of
600 2. Measurements across other impedances will be in db,
but not dbm.
To convert a db reading to dbm, use the Impedance Correction
Graph (Figure 3-3). For example: To convert a +30 db reading
made across 50 2 to dbm, locate the load impedance on the bot-
tom of the graph. Follow the impedance line to the heavy black
line and read the meter correction at that point. The correction
for 50 Q is +10.5 dbm, and the corrected reading is +40.5 dbm.
3-10. AC to DC Converter.
Follow steps a through e in Paragraph 3-8.
Connect the rear panel DC OUTPUT terminals to a dc measuring
device with a high input impedance. The dc output resistance is
1000 Q; and if it is loaded, the dc output signal will be inaccurate.
The de output is a 0 to 1 volt signal proportional to the percentage
of 400E/EL meter deflection.
3-11. Wide Band AC Amplifier.
a.
Poe oS: -S
Follow turn-on steps a through c in Paragraph 3-8.
Select approximate range of input on RANGE switch.
Connect SIGNAL to be amplified to INPUT terminals.
Connect a 50 2 amplifier load to rear panel AC OUTPUT connector.
The gain of the amplifier depends on the RANGE selection. On
the 0.1 volt range and below, the 400E/EL amplifies the input; and
on the 0.3 volt range and above, it attenuates the input. On the
0.001 volt ranges, the maximum output is 105 mv. On all other
ranges, the maximum output is 150 mv. Table 3-2 shows the ac
amplifier gain for each range setting.
3-12. 400E WITH OPTION 01.
3-13. Operation of the 400E with Option 01 is essentially the same as operation
of the standard 400E. The db scale reads from -15 to +2 instead of from -12
to +2, and is placed at the top of the scale for better resolution.
3-5

Section TI
Figure 3-3
+
)
+
($4)
oO
=
ao
Qa
I
=
2
bt
O
lu
a
a
oO
O
x
uJ
a
re)
=
a)
3-6
Model 400E/EL
af SOAIAAEIUOGGHIAFEGUGUAITNGGGIAIUUSOOIHIUIUGUGIILL
mmee Ett
A 8 A eS
10K
IMPEDANCE — OHMS
Figure 3-3. Impedance Correction Graph
0 es ant
0k ee eee
100K
400€/EL-8-0477

Model
400E/EL
Section
II
Paragraphs
3-14
to
3-18
Table 3-2. AC Amplifier Gain
3-14. 400E/EL WITH OPTION 02.
3-15.
Option
02
adds
a
relative
reference
adjustment
to
the
400E/EL.
This
adjustment
allows
a
continuous
reduction
in
sensitivity
by
3
db.
Use
the
REL.
REF
adjustment
to
set
the
meter
at
any
convenient
reference
(0
db
for
example)
in
order
to
make
relative
readings
easier.
When
the
REL.
REF
adjustment
is
in
the
fully
clockwise
ABSOLUTE
position,
it
has
no
effect
on
the
meter
sensitivity.
3-16.
In
all
other
respects,
operation
of
an
Option
02
instrument
is
the
same
as
operation
of
a
standard
Model
400E/EL.
3-17. 400E/EL WITH OPTION 03.
3-18.
An
Option
03
instrument
has
a
constant
input
capacity
of
28
pf.
Opera-
tion
is
the
same
as
operation
of
a
standard
instrument.

Model 400E/EL
Section IV
igure 4-1
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