HP 335E Owner's manual
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AURAL DEVIATION
METER
Range:
Accuracy:
AURAL MODULATION
METER
Rang
e:
Accuracy:
Polarity:
PEAK
MODULATION INDICATOR
Range:
Polarity
:
AUDIO
OUTPUT
High
Impedance:
Low
Impedance:
Freq
u
ency
Response:
VISUAL
DEVIATION
METER
Range:
Accuracy:
SPECIFICATIONS
±
3 kc
from
assigned
center
frequency.
±
500
cps
for
30
days,
channels
2-13
.
± 500
cps
for
10
days,
channels
14-83
.
Model 335E
0
to
133%
(25-kc
swing
equals
100%).
Also
calibrated
in
db
from
-10
to
+2
(0
db
equals
100%
modulation).
Indicates
modulation
percentage
within
±5%
for
modulation
frequencies
between
SO
and
15,000
cps.
Responds
to
positive
or
negative
peaks
as
selected
by
front
panel
switch.
Flashes
when
any
preset
modulation
level
is
reached
between
50%
and
120%.
Responds
to
positive
or
negative
peaks
as
selected
by
front
panel
switch.
10
volts
into
100,
000
ohms,
unbalanced,
at
100%
modulation
at
low
frequencies.
Distortion
less
than
.25%
at
100%
modulation
.
Noise
at
least
65
db
below
output
level
cor-
responding
to
100%
modulation
at
low
frequencies.
l
milliwatt
(0 VU)
into
600
ohms,
balanced,
at
100%
modu-
lation
at
low
frequencies.
Flat
within ±
.5
db
from
50
to
15,000
cycles,
with
standard
75-m
i
crosecond
de-emphasis
.
±
3
kc
from
assigned
frequency
.
±
500
cps
for
30
days,
channels
2-13.
±
500
cps
for
10
days,
channels
14-83.
ii
~
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Model
335E
SPECIFICATIONS
(CONT'D.)
RECEIVED
INTER-CARRIER
SP
ACING
MAY
6
1966
MOSELE't
ASSOCIATES(
ln
Range:
Accuracy:
GENERAL
RF
Power
Required:
Frequency
Range:
Power
Required:
± 3 kc
from
4,5
me.
±
500
cps
for
6
months.
Less
than
1
watt
from
each
transmitter.
Separate
type-N
connectors
provided
for
aural
and
visual
inputs.
Any
television
broadcast
channel
as
specified
from
2
to
83,
including
offset
channels.
115
volts±
10%,
60
cycles,
280
watts.
Ambient
Operating
Temperature:
Unit
must
be
mounted
where
ambient
temperature
will
not
exceed
45oC
(113°P).
Space
Required:
Weight:
Accessories
Furnished:
Accessories
Available:
Unit
mounts
in
a
standard
19-inch
rack
and
requires
12-1/4
inches
of
vertical
space
and
is
approximately
15-inches
deep.
Approximately
68
lbs.
Shipping
approximately
107
lbs.
2
125-UG21B/U
Type-N
Connectors
for
rf
inputs.
External
Aural
Deviation
Meter
Assembly,
335E-95F.
External
Aural
Modulation
Meter
Assembly,
335E-95G.
External
Visual
Carrier
Deviation
Meter
Assembly,
335E-95H
.
....------------------
CAUTION
--------------
----,
CIRCUIT DAMAGE MAY
RESULT
FROM
EXCESSIVE
RF
INPUT
TO
THIS INSTRUMENT. FOLLOW
THE
INSTRUC-
TIONS
IN
PARAGRAPH
2-1
TO
ADJUST
RF
INPUT
LEVEL.
iii
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SECTION I
SECTION II
SECTION
III
SECTION IV
SECTION V
CONTENTS
DESCRIPTION AND INSTALLATION
l
-l
Description.
.
l -
2
Installation
1
-
3 Input
Connectors
.
1 -4
Output
Connectors
.
OPERATING
INSTRUCTIONS
2 - 1
2 - 2
2 - 3
2 - 4
2 - 5
Initial
Operation
and
Tran
s
mi
tter
Coupling
Adjustment
Periodic
Calibration
....
. .
Master
Oscillator
Adjustment.
. .
Daily
Operating
Procedure
....
Aural
Amplitude
Modulation
Check
THEORY
OF
OPERA
Tl
ON
3 - 1
3 - 2
3 3
3 4
3 5
3 6
3 7
3 8
3 9
General
Operation
. •
Master
Oscillator
Multipliers
Aural
Mixer
. . . .
Aural
Amplifier,
Discriminator,
and
Deviation
Meter
Audio
Circuits
and
Modulation
Indicators
. . . . . . .
Visual
Mixer
and
4.3535-MC
Oscillator/Mixer
....
Visual
Amplifiers,
Discriminators,
and
Deviation
Meter
.
Power
Supply.
. . . . . . . . . . . . . . . . . . . . • . .
MAINTENANCE
4 - 1
4 - 2
4 - 3
4 - 4
4 - 5
4 -
6
4 - 7
4 - 8
4 -
9
4 -
10
4 -
11
4 -
12
4 - 13
4 - 14
4 -
15
Introduction
. . . . . . . . • .
Meter
Lamp
Replacement
. . .
Removing
Instrument
from
Rack
Troubleshooting
.
Tube
Replacement
.
Oven
Maintenance
. .
Power
Supply
Check
.
Audio
Amplifier
Check
Aural
Calibration
. .
Peak
Modulation
Indicator
.
Visual
and
lntercarrier
Calibration
.
Master
Oscillator
Adjustment
• . .
Multiplier
/Mixer
Tuning . . . . .
4.3535-MC
Oscillat9r
Adjustment.
150-KC
Oscillator
Check
.
....
TABLE
OF
REPLACEABLE
PARTS
5 - 1
Table
of
Replaceable
Parts
iv
Model
335E
PAGE
I - 1
I - 1
I - 2
I -
3
II
- 1
II
- 1
II - 4
II - 4
II
- 5
Ill
- 1
III
- 1
Ill
- 1
Ill
- 1
III
- 2
III - 2
III
- 3
III
- 3
III
- 3
IV
- 1
IV - 1
IV
-1
IV -1
IV
-
6
IV
-
6
IV -
8
IV
-
8
IV -9
IV
-
10
IV -
10
IV
-
10
IV
-
10
IV
-
11
IV
-
11
V - 1
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Model
335E
Sect.
1
Page
l
SECTION
I
DESCRIPTION
AND
INSTALLATION
1-1
DESCRIPTION
The
t$jJ
Model
335E
Television
Monitor
is
a
com-
plete
transmitter
frequency
and
aural
modulation
percentage
monitor
tor
any
commercial
TV
channel
from
2
through
83.
Type
approval
number
3-110
has
been
issued
by
the
Federal
Communications
Commission
for
all
l$p
Model 335E
Type
2
TV
Monitors.
Continuous
indication
of
any
deviation
from
as-
signed
frequency
is
indicated
by
panel
meters.
In
addition,
any
deviation
from
the
standard
4.5
me
intercarrier
separation
may
be
read
directly.
A
meter
is
provided
to
monitor
aural
transmitter
modulation;
a
peak
modulation
indicator
lamp
flashes
a
warning
when
instantaneous
aural
modu-
lation
exceeds
any
preset
value
between
50%
and
120%. An
audio
output
is
also
provided
for
moni-
toring
and
measurement
purposes.
This
output
is
equipped
with
the
standard
75-microsecond
de-
emphasis
circuit.
The
Model
335E
can
also
be
used
for
performing
other
tests
required
for
proper
operation
of
a
television
station
such
as
the
measurement
of
in-
cidental
AM
of
the
FM
aural
carrier,
frequency
response
and
distortion
checks
on the
aural
trans-
mitter,
residual
noise
on
th
e
aural
carrier,
and
carrier
shift
with
modulation.
The
335E
utilizes
pivoted-drawer
mounting
within
the
rack
so
that
it
can
be
pulled
out
and
tilted
up
for
convenient
insp
ec
tion.
The
cabinet
for
the
335E
contains
the
drawer
mechanism
which
mounts
on
the
rack
frame.
The
instrument
chassis
is
easily
remov
ed
from
the
drawer
mounting
if
desired.
In
addition
to
this
manual,
the
following
items
are
included
with
your
instrument:
1)
Two
type
-N
connectors
(UG-21B/U).
2)
One
set
of
rack-mounting
hardware.
1-2
INSTALLATION
The
instrument
is
supplied
with
all
ne
cessary
hard-
ware
for
mounting
in
a
standard
19-inch
rack
that
has
been
drilled
and
tapped
for
12-24
mounting
screws.
The
vertical
height
requir
ed
is
approxi-
mately
12-1/4
inches.
The
rack
should
be
fastened
to
the
floor
for
stability.
For
easy
access
to
the
unit
when
it
is
out
of
the
rack,
it
is
suggested
that
the
instrument
be
mounted
so
the
bottom
of
the
panel
is
approximately
50
inches
off
the
floor.
The
unit
should
be
installed
in
a
well-ventilated
location
where
the
ambient
temperature
does
not
exceed
45oc
(113°F).
It
is
also
important
to
allow
sufficient
clearance
behind
the
unit
for
free
passage
of
air
out
of
the
dust
cover.
To
mount
the
335E
in
a
relay
rack
proceed
as
follows:
(D
Disconn
ec
t fan
power
cord
at
rear
of
the
instrum
e
nt.
Slide
instrument
from
cabinet
after
pushing
catches
on
chassis
rails.
www.SteamPoweredRadio.Com
Sect.
I
Page
2
Q)
Mount two
angle-brackets
in
rack
using
four
12-24
screws
supplied.
Make
sure
brackets
are
parallel
and
far
enough
apart
to
clear
cabinet.
0
Extend
chassis
slides
from
dust
cover
until
they
lock
in
position.
Engage
in-
strument
in
chassis
slides.
Depress
catches
to
lock
it
in
place.
1-3
INPUT
CONNECTORS
,
All
connections
are
made
at
the
back
of
the
335E
along
the
lower
edge
(see
Figure
1-1).
Allow
enough
slack
in
all
wires
and
cables
so
that
the
335E
will
slide
from
the
rack
without
disconnecting
cables.
A. POWER
LINE
The
three-conductor
power
cable
supplied
with
this
instrument
is
terminated
in
a
polarized
three-
prong
male
connector
recommended
by
the
National
Model
335E
(D
Fasten
cabinet
to
angle
brackets
with
six
8-32
screws
and
lockwashers
pro-
vided.
Adjust
angle
brackets
for
snug
fit.
(D
Connect
fan
cord
at
rear
of
in
str
ument.
Slide
335E
into
rack.
The
12-24
screws
should
come
through
holes
in
panel.
Attach
four
cap
nuts
provided.
Electrical
Manufacturers'
Association.
The
third
contact
is
an
offset
,
round
pin
added
to
a
standard
two-blade
connector
which
grounds
the
335E
chassis
when
used
with
the
appropriate
receptacle.
Touse
this
connector
in
a
standard
two-contact
receptacle,
an
adapter
should be
used
to
connect
the
NEMA
con-
nector
to
the
two-contact
system.
When
th
e
adapter
is
used
th
e
ground
connection
becom
es
a
short
l
ea
d
which
should
be
connected
to
a
secure
ground.
Th
e
instrum
e
nt
should
be
connect
ed
to
a
115-volt
power
source
that
is
never
de-energized.
This
is
~
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I
Model
335E
to
allow
the
crystal
oven
heater
circuit
to
operate
continuously
for
maximum
oscillator
stability.
Th
e
POWER
switch
on
the
panel
controls
all
the
power
applied
to
the
instrument
except
th
e
crystal
oven
heater
circuits.
B.
RF
INPUTS
Conn
ec
t
the
VISUAL
and
AURAL
RF
INPUT
conectors,
located
on
the
rear
of
the
instrument
with
the
appropriate
monitoring
outputs
provided
on
the
tran
smitte
r.
Table
1-1
lists
types
of
cable
and
connectors
which
can
be
u
sed
at
the
monitor.
Assembly
instructions
for
coaxial
connectors
are
given
in
Figure
1-2
and
1-3.
REMOTE
METER
JACKS
THERMAL
CUTOUT
RESET
0
I
~ I
<,
•·
•
4,
.,.,
u ,
w,
,nt
Q
0
~ -
CONNECT
TO
TRANSMITTERS
FAN
CONNECTOR
7-8
TO
REMOTE
PEAK
MOD
INDICATOR
4
-5
PROVIDE
HI-Z
AUDIO OUTPUT
SHORT
3-4
FOR
soon
OUTPUT
1-2 PROVIDE
600
.
fi
AUDIO OUTPUT
MP.S-5708
Fi~ure
1-1.
Rear
View Showing
Connectors
The
amount
of
rf
pow
er
required
from
the
trans-
mitters
for
prop
er
operation
of
the
335E
Monitor
is
very
small,
and
should
be
maintained
within
reasonably
close
limits
.
The
input
voltage
to
the
monitor
should
fall
in
the
range
of
0.05
volt
to
l.S
vo
lt
s.
The
value
incr
ea
ses
with
frequency
of
operation.
Adjustment
of
tran
smi
tter
coupling
is
de
scribed
in
paragraph
2-1.
Sect.
I
Page
3
TABLE
1-1.
INPUT
CABLE
AND
CONNECTOR
Cable
Connectors
RG-8
/U
UG-218/U
(furnished)
RG-
9/U
or
RG-9A/U
RG
-1
0/U
UG-21O/U
RG-55/U
UG-536/U
RG/58/U
Since
the
voltage
required
is
small,
care
must
be
taken
to
insure
that
excessive
rf
pow
er
is
not
coupled
into
the
monitor
which
can
result
in
severe
damage
to
the
input
circuits.
The
diodes
CR7
and
CR8
will
burn
out
if
overloaded.
If
the
monitor
seems
to
require
excessive
rf
input
for
proper
monitoring
l
eve
l,
check
th
ese
diodes
.
1-4
OUTPUT
CONNECTORS
All
connec
tions
ar
e
made
at
the
rear
of
the
335E
chassis.
Allow enough s
lack
in
all
wires
and
cables
to
permit
the
instrument
to
be
slid
from
the
ra
ck without
disconnecting
cables.
A. AUDIO
OUTPUT
Two
audio
output
voltages
are
available
on
the
terminal
strip
at
the
rearoftheinstrument:
A
bal-
anced
low-impedan
ce
output
for
monitoring
pur-
po
ses,
and
an
unbalanced
high-imp
e
dance
output
for
nois
e
and
distortion
measurement
purposes
.
Both
of
these
outputs
contain
the
standard
75-micro-
second
de-emphasis
circuit.
Only
one
of
these
out-
put
circuits
should
be
u
sed
at
a
time.
The
unba
l-
anc
ed
output
should
be
us
ed
for
distort
ion m
eas
ure-
ment
s
to
e
liminate
the
small
amount
of
distortion
introduc
ed
by the
output
tra
ns
form
er
in
the
bal-
anced
output.
A
balanced
low-impedance
output
(600
ohms)
is
availab
le
at
terminals
l
and
2
at
the
back
of
th
e
inst
r
ument
(see
Figure
1-1).
The
output
level
of
this
circuit
is
approximately
1
milliwatt
(0
VU)
into
a
600-ohm
circuit,
with 100%
modulation
at
low
frequencies
. A
connection
must
be
made
be-
tween
terminals
3
and
4
as
indicat
ed
on
the
sche-
matic
diagram,
before
the
low-impedanc
e
output
will
operat
e.
Double-conductor
shielded
cable
s
hould
be
used
for
this
circuit.
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Sect.
l
Page
4
An
unbalanced
high-impedance
audio
output
is
available
between
terminals
4
and
5
at
the
rear
of
the
instrument.
When
the
unbalanced
output
is
in
use
there
should
be no
connection
between
ter-
minals
3
and
4.
The
output
level
of
this
circuit
is
approximately
10
volts
into
a
100,000-ohm
load
with
100%
modulation
at
low
frequencies.
Shielded
cable
should
be
used
for
this
circuit.
B.
REMOTE
INDICATORS
External
meters
may
be
used
with
the
instru-
ment
to
duplicate
all
three
panel
meters
at
some
remote
location.
Meters
for
remote
indication
may
be
ordered
from
the
Hewlett-Packard
Com-
pany.
Refer
to
Section
V,
Table
of
Replaceable
Parts,
for
procurement
instructions
and
stock
numbers.
Meters
should
be
mounted
in
a
non-magnetic
(e.g.
a
luminum)
panel
for
maximum
accuracy.
The
meters
may
be
illuminated
from
an
external
6.3-
volt
power
source.
Model
335E
1)
Aural
DeviatiQg:
The
remote
aural
deviation
meter
is
connected
to
J6
with
double
conductor
shielded
cable
and
a
three-circuit
phone plug.
The
positive
meter
terminal
should
be
connnected
to
the
tip
of
the
plug
and
the
remote
meter
mul-
tiplier
to
the
ring.
The
plug
sleeve
should
be
connected
to
the
cable
shield
at
the
instrument.
2)
Modulation
Aural
Carrier:
The
remote
mod-
ulation
meter
is
connected
to
J7
with
single
con-
ductor
shielded
cable
and
a
standard
two
conduc-
tor
phone plug.
The
positive
meter
terminal
should
be
connected
to
the
shield
(grou
n
d).
3)
Visual
Carrier
Deviation:
The
remote
visual
carrier
deviation
meter
is
connected
to
J4
with
single
conductor
shielded
cab
le
and
a
standard
two
conductor
phone
plug.
The
positive
meter
terminal
should
be
connected
to
the
s
hi
eld
(ground).
4)
Peak
Modulation
Indicator:
A
remote
peak
modulation
indicator
may
be
connected
to
termi-
nals
7
and
8
at
the
rear
of
the
instrument
.
This
indicator
should
be
a 3
or
6
watt,
type
S6, 120
volt,
incandescent
lamp,
mounted
in
a
suitable
socket.
www.SteamPoweredRadio.Com
Model
335E
Sect
. I
Page
5
ASSEMBLY
OF
UG-21B/U
CONNECTOR
AND
RG-9
/U
CABLE
Cut
the
RG-9/Ucabletothedesiredlength
.
Remove
3/4
inch
of
the
outer
protective
covering
from
the
end
of
the
cable.
Do
not
injure
the
shield
braid
when
cutting
the
outer
coveri
ng
.
Slide
the
shield
braid
back
and
remove
1/4
inch
of
the
die-
lectric
material.
Do
not
nick
the
center
conductor
wh
en
cutting
the
dielectric
.
Slide
shield
braid
back
over
the
end
of
the
center
conductor
and
taper
to
allow
connector
parts
to
slide
over
cable.
Assemble
the
parts
of
the
connector
on
the
cable
as
shown.
Slide
end
fitting
D down
until
it
fits
tightly
over
the
outer
plastic
covering
of
the
RG-9/U.
Unbraid
and
fan
the
shield
braid
over
the
tapered
end
fitting.
Trim
the
shield
braid
around
the
edge
of
the
end
fitting
as
indicated.
Cut
the
dielec
tric
1/8
inch
from
t
he
shield
braid.
Do
not
nick
the
center
conductor
when
cutting
the
dielectric.
Cut
off
the
center
conductor
1/4
inch
from
the
dielectric.
Slide
tip
E
over
the
center
conductor
and
solder
in
place.
Do
not
apply
excessive
heat
when
soldering
the
tip
in
place
as
it
will
melt
the
dielectric
.
If
the
dielectric
is
slightly
bulged
after
soldering
the
tip
in
place,
it
will
be
necessary
to
trim
it
to
conform
to
the
large
diameter
of
the
tip
so
that
it
will
fit
properly
into
the
outer
shell
.
Pl
ace
outer
shell
F
over
the
cable
end.
Tip
E
should
slide
into
shell
F
until
it
is
flush
with
the
end
of
the
shell.
Now
tighten
the
assembly
by
turning
nutA
while
holding
the
outer
shell.
Figure
1-2
~
-"
.!."
4
www.SteamPoweredRadio.Com
Sect.
I
Page
6
ASSEMBLY
OF
UG-536/U
CONNECTOR
AND
RG-55/U
CABLE
Cut
RG-55/U
cable
to
the
desired
length.
Remove
3/4
inch
of
the
outer
protective
covering
from
the
end
of
the
cable.
Do
not
injure
the
shield
braid
when
cutting
the
outer
covering.
Slide
back
the
shield
braid
and
remove
1/4
inch
of
the
die-
lectric
material.
Do
not
nick
the
center
conduct
or
when
cutting
th
e
dielectric.
Slide
shi
e
ld
braid
back
over
the
end
of
the
center
conductor
and
taper
to
allow
connector
parts
to
slide
over
cable.
Ass
e
mbl
e
the
parts
of
the
connector
on
the
cable.
Slide
end
fitting
D down
until
it
fits
tightly
over
the
outer
plastic
covering
of
the
RG-55/U
cable.
Unbraid
and
fan
the
shield
braid
over
the
tapered
end
fitting.
Cut
the
dielectric
1/8
inch
from
the
shield
braid.
Do
not
nick
the
center
conductor
when
cutting
the
dielectric.
Cut
off
the
center
conductor
1/4
inch
from
the
dielectric.
Tin
the
exposed
inner
conductor.
Do
not
apply
e
xcessive
heat
to
the
center
conductor
as
this
will
melt
the
dielectric.
Slide
tip
E
over
th
e
center
conductor
and
solder
in
place.
Do
not
apply
excessive
heat
when
soldering
the
tip
in
place
as
it
will me
lt
the
dielectric.
If
the
dielectric
is
slightly
bulged
after
soldering
the
tip
in
place,
it
will
be
necessary
to
trim
it
to
conform
to
the
large
diameter
of
the
tip
so
that
it
will
fit
properly
into
the
outer
shell.
Place
the
outer
shell
F
over
the
cable
end.
Tip
E
should
slide
into
shell
F
until
it
is
flush
with
th
e e
nd
of
the
shell.
Now
tighten
the
assembly
by
turning
nut
A
while
holding
the
out
er
sh
e
ll.
Figure
1-3
r:::,
....
Model
335E
www.SteamPoweredRadio.Com
Model
335E
2-1
INITIAL
OPERATION
AND
TRANSMITTER
COUPLING
ADJUSTMENT
Proceed
as
follows
after
the
monitor
is
installed
and
rf
cables
to
the
transmitters
are
connected:
1)
Connect
the
335E
to
the
115-volt,
60-cycle
power
line.
Observe
CRYSTAL
TEMPERATURE
thermometer
during
warm-up;
it
should
not
ex-
ceed
70oC
(green
area
of
scale)
.
2)
Adjust
monitor
rf
coupling
at
transmitters
as
follows:
a.
Adjust
monitoring
output
from
each
trans-
mitter
to
minimum.
b.
Energize
transmitters.
c.
Set
function
selector
switch
to
CARRIER
LEVEL
position.
d.
Adjust
coupling
at
visual
transmitter
for
a
reading
of
+ 1
to
+ 3
kc
on
the
VISUAL
CARRIER DEVIATION
meter
with
trans-
mitter
operating
at
normal
power
with
black
level
and
sync
pulse
modulation
only.
e.
Adjust
coupling
at
aural
transmitter
for
a
reading
of+
1
to+
3
kc
on
the
AURAL DEVI-
ATION
meter
with
transmitter
operating
at
normal
power.
3)
Proceed
with
calibration
procedure
given
in
paragraph
2-2.
2-2
PERIODIC
CALIBRATION
Use
the
following
calibration
procedure
after
initial
transmitter
coupling
adjustment
and
at
weekly
in-
tervals
thereafter
to
assure
accurate
monitor
operation.
Sect.
II
Page
I
SECTION
II
OPERATING
INSTRUCTIONS
1)
Turn
on
monitor
and
allow
to
warm
up
for
30
minutes.
2)
Calibrate
aural
circuits.
Refer
to
Figure
2-1,
number
15.
3)
Calib
r
ate
visual
circuits.
Refer
to
Figure
2-l,
number
9.
4)
Calibrate
intercarrier
circuits.
Proceed
as
follows:
a.
Set
function
selector
to
CALIBRATE.
b.
Connect
3500-cycle
audio
oscillator
to
Jl
.
Both
deviation
meters
should
now
indicate
zero
if
steps
2
and
3
have
been
completed
properly.
c.
Set
the
DEVIATION
switch
to
INTERCAR-
RIER.
Any
shift
in
audio
oscillator
fre-
quency
should
now
produuce
equal
and
oppo-
site
indications
on
the
two
deviation
meters.
For
example:
if
the
oscillator
frequency
is
shifted
to
6500
cycles
the
VISUAL
CAR-
RIER
DEVIATION
meter
indication
should
shift
to+
3
KC
and
the
AURAL DEVIATION
meter
(now
indicating
intercarrier
devi-
ation)
should
indicate
-3
KC.
If
it
does
not,
adjust
R294
(inside
the
instrument
near
Vl5)
until
the
AURAL DEVIATION'
meter
indication
is
equal
and
of
opposite
polarity
to
the
VISUAL CARRIER
DEVI-
ATION
meter
indication.
5)
Check
"l"
position
of
function
selector
switch
as
follows:
a.
Set
the
function
selector
to
"l".
b.
The
VISUAL CARRIER DEVIATION
meter
monitors
grid
current
in
the
visual
mixer
(V3)
and
should
indicate
between
+ 1
kc
and
+3
kc.
www.SteamPoweredRadio.Com
Sect.
II
Page
2 Mcxlel
335E
FRONT PANEL
CONTROLS
AND
INDICATORS
.
,,
•· ·•
3l
~11~:--
'& ~©<,
L
i'•ri-i
1.
VISUAL CARRIER DEVIATION
meter
indi-
cates
deviation
from
assigned
visual
carrier
frequency
when
function
switch
is
in
USE
position.
2. MODULATION AURAL CARRIER
meter
in-
dicates
percent
mcxlulation
of
aural
carrier.
Since
meter
damping
averages
complex
mcxl-
ulation
wave
forms,
it
will
notindicatepeaks
during
normal
mcxlulation with
speech
or
music.
3.
AURAL DEVIATION
meter
indicates
devi-
ation
from
assigned
aural
carrier
frequency
when function
switch
is
in
USE
position
and
DEVIATION
switch
is
in
AURAL CARRIER
position.
Indicates
deviation
from
required
4.5-mc
carrier
separation when
DEVIATION
switch
is
in
INTER-CARRIER
position.
4. CRYSTAL
TEMPERATURE
thermometer
gives
temperature
inside
mast
er
oscillator
crystal
oven.
Pointer
should
lie
inside
gr
ee
n
area
(approximately
65oC).
5.
PEAK
MODULATION INDICATOR
flashes
if
instantaneous
mcxlulation
peaks
exceed
value
selected
on 50%-120%
control.
6. 50%-120%
control
selects
modulation
per-
centag
e
at
which
the
PEAK
MODULATION
INDICATOR
flashes,
7,
FUNCTION
switch
is
normally
set
to
USE
position
.
See
Table
2-1
for
other
settings
.
8. DEVIATION
switch:
AURAL CARRIER
position
permit
s AURAL
DEVIATION
meter
to
indicate
aural
fre-
quency deviation.
INTER-CARRIER
position
permits
AURAL
DEVIATION
meter
to
indicate
de
viation
of
carriers
from
norma
l
4.5
me
separation.
Fi
gure
2-1
www.SteamPoweredRadio.Com
Model
335£
Sect
. II
Page
3
FRONT PANEL CONTROLS
AND
INDICATORS {CONT'D)
9.
Calibration
of
visual
circuits:
a)
Set
function
switch
to
USE.
b)
Connect
accurate
3500-cps
(±
10
cps)
oscillator
with
at
least
one
volt
output
to
Ji.
c)
Adjust
"A"
to
center
VISUAL
CARRIER
DEVIATION
meter
(o
kc).
d)
Change
frequency
to
5000
cps.
e)
Adjust
"B"
for+
1.5
kc
on
meter.
10.CRYSTAL TUNING
control
adjusts
frequency
of
master
oscillator.
Adjust
so
that
AURAL
CARRIER DEVIATION
meter
agrees
with
simultaneous
report
from
monitoring
serv-
ice.
11.
TEST
button
lowers
oscillator
frequency
slightly
when
pressed.
Both
deviation
meters
should
deflect
to
the
right
when button
is
pressed.
Shift
is
0.3
kc
on
channels
2
thru
4.
Shift
is
0.5
kc
on
channels
5
thru
13.
Shift
is
1.0
kc
on
channels
14
thru
83.
12.
POWER
switch
controls
all
power
to
instru-
ment
except
for
crystal
ovens.
13.
FUSE
protects
all
circuits
except
for
crystal
ovens.
Oven
fuse
is
located
on
re
ar
of
chassis.
A
thermal
switch
turns
Q.OWer
off
if
internal
temperature
exceeds
130°F;
refer
to
Section
IV,
Maintenance,
to
reset.
14.MODULATION
POLARITY
switch
permits
check
of
modulation
symmetry.
MODULA-
TION AURAL CARRIER
meter
should
have
same
reading
in
either
switch
position.
15.Calibration of aural circuits:
a)
Set
function
switch
to
CALIBRATE.
b)
Set
DEVIATION
switch
to
AURAL
CAR-
RIER.
c)
Adjust
"D"
for
100% on MODULATION
AURAL
CARRIER
meter
. .
d)
Adjust
"C"
to
center
AURAL DEVIATION
meter
(0 kc).
Figure
2-1
(Cont'd.)
www.SteamPoweredRadio.Com
Sect.
II
Page
4
c.
The
MODULATION AURAL
CARRIER
me-
ter
monitors
grid
current
in
the
first
mul-
tiplier
(V2),
and
should
indicate
at
least
10%
(arbitrary
reading
).
This
meter
in-
dication
checks
the
op
e
ration
of
the
master
oscillator
(Vl)
and
the
first
multiplier
(Y2).
d.
The
AURAL DEVIATION
meter
monitors
grid
current
in
the
aural
mixer
(VS)
and
should
indicate
between
+ 1
kc
and
+
3
kc.
6)
Check
"2"
position
of
function
selector
switch
as
follows:
a,
Set
the
function
selector
to
"2".
b.
The
VISUAL
CARRIER
DEVIATION
meter
monitors
grid
current
in
the
4.3535-mc
crystal
oscillator
(V4)
and
should
indicate
between
+ l kc
and
+
3
kc.
c.
The
MODULATION AURAL CARRIER
me-
ter
is
not
connected
and
its
reading
has
no
significance.
d.
Th
e AURAL DEVIATION
meter
monitors
ma
s
ter
oscillator
AGC
voltage
and
should
indicate
about
+
0.5
kc.
7)
Energize
transmitter
and
check
tuning
as
fol-
lows:
a.
Set
function
selector
switch
to
USE.
b.
Set
DEVIATION
switch
to
AURAL
CAR-
RIER.
c.
Press
TEST
button.
Both
deviation
meters
should
deflect
0.3
to
1
kc
to
the
right.
8)
Adjust
master
oscillator
frequency
after
335E
has
been
connected
to
power
line
for
at
least
24
hours.
Refer
to
paragraph
2-3.
2-3
MASTER
OSCILLATOR
ADJUSTMENT
The
CRYSTAL TUNING
control
should
not
be
ad-
justed
without
consulting
an
approved
monitoring
service:
No
adjustments
should
be
attempted
until
the
unit
has
been
connected
to
the
power
line
(
crys-
tal
oven
operating)
for
a
continuous
pe
riod
of
24
hours
and
the
complete
instrument
has
been
turn-
ed
on
for
at
least
one
hour.
Mcxiel
335E
The
best
methcxi
of
adjusting
the
CRYSTAL
TUN-
ING
control
requires
telephone
co
ntact
with
a
monitoring
service.
Adjust
th
e CRYSTALTUNING
control
until
the
AURAL DEVIATION
meter
(with
DEVIATION
switch
in
AURAL
position)
correspo
nds
exactly
with
the
report
given
by
the
monitoring
service.
The
VISUAL CARRIER DEVIATION
meter
should
now
agree
very
closely
with
the
re-
port
of
the
monitoring
service.
If
it
does
not,
refer
to
paragraph
4-14,
4.3535-mc
Oscillator
Adjustment.
Another
method
of
adjusting
the
master
oscillator
may
be
used
when
direct
contact
with
the
moni-
toring
service
is
impractical.
When
the
monitor-
ing
service
report
is
received,
check
the
trans-
mitter
log
for
the
day
and
time
the
measurement
was
made.
If,
for
example,
the
monitoring
service
report
indicat
es
the
aural
transmitter
was
500
cycles
high
and
the
log
indicates
the
aural
trans-
mitter
was
300
cycles
high
at
the
same
time,
the
indication
is
that
the
Mcxiel
335E
was
in
error
by
200
cycles.
To
correct
this,
adjust
the
CRYSTAL
TUNING
control
to
raise
the
present
AURAL
DEVI-
ATION
indication
by
200
cycles.
2-4
DAILY
OPERATING
PROCEDURE
1)
Operate
function
selector
switch
to
CALIBRATE.
Turn
the
POWER
switch
on.
Allow
at
least
30
minutes
warm-up
before
making
any
adjustments.
2)
Check
CRYSTAL
TEMPERATURE.
It
should
be
stable
at
6SoC
±
s0
(within
th
e
green
sector).
3)
Check
aural
circuit
calibration.
See
Figure
2-1.
number
15.
4)
Set
the
function
selector
switch
to
"2".
The
VISUAL CARRIER DEVIATION
meter
should
in-
dicate
between
+
1
kc
and
+
3
kc.
5)
Set
function
selector
to
the
"l"
position.
The
CARRIER
DEVIATION
meters
should
indicate
between
+ 1
kc
and+
3
kc.
6)
After
both
transmitters
are
on
the
air
set
the
function
selector
to
CARRIER
LEVEL.
Both
DEVIATION
meters
should
indicate
between
+ 1
kc
and
+
3
kc
with
black
le
vel
and
sync
pulse
mcxiu-
lation
only.
7)
Set
the
function
selector
switch
to
USE
and
the
DEVIATION
switch
to
AURALCARRIER
for
normal
op
erat
ion
of
the
monitor.
It
is
gocxi
practice
to
check
aural
circuit
calibration
(Figure
2-1,
num-
ber 15)
before
recording
AURAL
DEVIAT
·-·~
meter
readings.
www.SteamPoweredRadio.Com
Model
335E
If
monitor
is
operated
with
function
selector
switch
in
USE
position
without
a
signal
input,
it
may
give
false
readings.
Correct
readings
will
return
when
proper
input
is
restored.
8)
Frequency
deviation
from
standard
4.5-mc
carrier
separation
is
shown
on
the
AURAL DEVI-
ATION
meter
when
the
DEVIATION
switch
is
oper-
ated
~o
INTER-CARRIER.
Sect.
II
Page
5
plug
inserted
into
JS
.
This
voltage
will
be
between
about
0.1
volt
and
3
volts.
Record
this
reading.
2)
Replace
the
de
yoltmeter
with a
sensitive
ac
voltmeter.
Read
and
record
the
ac
voltage.
3)
The
percentage
of
amplitude
modulation
may
then
be
obtained
with
the
following
formula:
w
pl
od
= 141.4 x
ac
voltage
to
am
.m
. d 1
C
VO
tage
2-5
AURAL
AMPLITUDE
MODULATION
CHECK
A
jack
is
provided
at
the
back
of
the
monitor
to
allow
measurement
of
incidental
amplitude
modu-
lation
on
the
aural
carrier.
The
measurement
can
be
made
at
JS
with a
sensitive
ac
voltmeter
such
as
an
~
Model
400D
or
the
voltmeter
section
of
an
1$
Model
330B/C/D
and
a
de
electronic
voltmeter
such
as
an
~
Model
410B.
Example: The
de
voltagemeasured1.78 volts.
The
ac
voltage
measured
0.0028
volts.
% 1
od
_ 141.4 X
0.0028
= O
22
%
0
amp
.m
. -
1.
78
. o
In
some
cases,
the
input
voltage
requirement
of
the
monitor
may
be
so
low
that
difficult
y
will
be
found
in
measuring
these
voltages.
In
this
case
it
is
permissible
to
readjust
the
coupling
probe
that
samples
the
aural
transmitter
output
so
that
a
de
level
of
up
to,
but
not
more
than,
three
volts
is
obtained.
Return
transmitter-to-monitor
cou-
pling
to
normal
setting
when me
asurement
is
csm-
pleted
.
Proceed
as
follows:
1)
With
the
function
selector
in
CARRIER
LEVEL
position,
measure
the
de
voltage
across
a
phone
TABLE
2-1.
METER
SWITCHING CHART
FUNCTION VISUAL CARRIER MODULATION AURAL
DEVIATION
METER
CARRIER
METER
SWITCH
Normal
Normal
POSITION
Indicates
Reading
Indicates
Reading
CA
RRIER
LEVEL
Visual
trans-
+ 1
to
+3
kc
. Not
----
mitter
in-
(No
visual
conn
e
cted
put
level
modulation;
"BLACK"
level).
1
Visual
mixer
+1
to
+3
kc.
First
multi-
Over
10%
grid
current
(No
rf
input)
plier
grid
current
USE
Visual
car-
KC
deviation
Aural
per-
Percent
rier
devia-
cent
modu-
Modulation
tion
lation
2
4.3535
me
+ 1
to
+3
kc
No
----
oscillator
significance
CALIBRATE
No
----
Aural
disc
r
i-
100%
significance
minator
con-
stant
current
AURAL DEVIATION
METER
Normal
Indicates
Reading
Aural
trans-
+l
to
+3
kc
.
mitter
input
level
Aural
mixer
+ 1
to
+3
kc
grid
current
(No
rf
input)
Aural
car-
KC
deviation
rier
or
inter-
carrier
de
-
viation
AGC
in
About + 0.
Skc
master
oscillator
Aura
l
IF
0
kc
www.SteamPoweredRadio.Com
Sect.
lII
Page
0
N
OTE
!
FRE
QU
EN
CIES
SH
O
WN
IN PARENTHESES
A
RE
F
OR
33
5E
TUN
ED
TO
M
ON,ITO
R
CHANN
El. 5 (
76
- 82 MC),
AURAL
~
~ ~
L
x~
i~f~r
)---------
NIXER
1
50K
C
(8
1.7
5 MC)
V5B
MASTER
(8
1.6
M
C)
OSCILLATOR
VI
(
20
..
IOM
C)
AURA
L
MULTIPLIER
VSA
MU
LTI
PLIER
(
40.8M
C)
V2
VI
SUAL
MULTIPLIER
V3A
(
81
.
6M
C)
VISUAL
VI
SUAL
RF
INPUT
>-------
NIXER
4
.35
MC
FROM XMITTER
-
(
77
.25
MC)
V38
SOU
AR
INC
-
USE
~
-
AM
PU
FIERS
9CA~
8R
A
TE
VT-
V9,
Vl
2
150
KC
OSCILLATOR
V4A
4.3535
NC
OSCILLATOR
V4A
l
SQUARING
NIXER
3.5
KC
AMPLIF
I
ER
S
3.5KC
V48
V13-Vl6
F
igu
re
3-1.
Block
Diagram
PEAK MODULATION
INDICATOR
@
I----+
AMPLIFIERS
VIO,
VII,
Vl
7
AUDIO
1
~010
-'-
OU
TP
UT
DISCRIMINATOR
DC
LEVEL,
CR3
-
Model
335E
MOOULATIO
N
AUR
AL CARR
IER
~
AURAL
DEVIA
TI
ON
ffi
I
INTER-CARRIER
')
'"""
VISU
AL C
ARRI
ER
DEVI
ATION
OCLEVEL,i
CTI
DISC
RIMIN
ATOR
CR6
www.SteamPoweredRadio.Com
Model
335E
3-1
GENERAL
OPERATION
Figure
3-1
shows
general
circuit
operation
for
all
instruments.
Master
oscillator
and
multiplier
frequencies
for
channel
5
only
are
given.
Specific
M.
0.
and
multiplier
frequencies
for
the
channel
to
which
a
particular
monitor
is
tuned
is
shown
on
a
label
attached
to
the
instrument.
The
output
of
th
e
master
oscillator
is
multiplied
to
a
frequency
150
kc below
the
assigned
center
frequency
of
the
aural
transmitter.
This
frequency
is
combined
with
the
aural
transmitter
frequency
to
produce
a
150-kc
intermediate
frequency.
The
output
of
the
discriminator
is
shown
on a
meter
which
indicates
deviation
from
assigned
frequency
.
Th
e
audio
discriminator
output
is
used
to
operate
a m
ete
r which
indicates
modulation
percentage
.
The
multiplied
master
oscillator
frequency
also
falls
4.35
me
above
assigned
visual
carrier
fre-
quency.
This
frequency
is
combined
with
the
visual
transmitter
frequency
to
produce
a
4.35-mc
int
e
rm
e
diate
frequency.
T
he
intermediate
fre-
quency
is
mixed
with
a
crystal-controlled
4.
3535-
mc
signal
to
produce
a
second
intermediate
fre-
quency
of
3.5
kc.
The
output
of
the
visual
dis-
criminator
is
used
to
operate
a
meter
which
in-
dicates
deviation
from
assigned
carrier
frequency
.
The
remaining
paragraphs
in
this
section
cover
detailed
circuit
operation;
consult
the
schematic
diagrams
at
the
rear
of
Section
IV,
Maintenance,
for
complete
circuit
diagrams.
3-2
MASTER
OSCILLATOR
The
master
oscillator
(VI)
is
the
standard
towhich
both
carriers
are
compared.
Crystal
frequency
is
in
the
19-
to
28-mc
range.
The
e
xact
frequency
is
shown
on a
label
attached
to
the
instrument.
Master
oscillator
frequency
is
always
chosen
so
that
one
of
its
harmonics
falls
150
kc
below
the
assigned
aural
carrier
frequency
and
4.35
me
above
Sect.
lII
Page
1
SECTION
Ill
THEORY
OF
OPERATION
th
e
assigned
v
isual
carrier
frequency
.
The
crystal
is
enclosed
in
a
temperature-controlled
oven
for
maximum
stability.
The
AURAL DEVIATION
meter
monitors
oscil-
lator
AGC
vol
tage
when
the
func
ti
on
selector
switch
is
in
the
"2"
position
.
3-3
MULTIPLIERS
The
first
multiplier
(V2)
is
common
to
both
aural
and
visual
channels.
It
is
usually
op
e
rat
ed
as
a
doubler;
however,
on
some
channels
it
is
used
as
a
tr
ip
ler.
The
MODULATION AURAL
CARRIER
meter
indicates
grid
current
in
this
stage
when
the
function
selector
switch
is
in
the
"l"
position.
Both
the
visual
multiplie
r
(half
of
V3)
and
the
aural
multiplie
r
(half
of
VS)
ar.e
driven
by
the
first
multi-
plier.
In
general
these
circuits
operate
as
doublers
::
although
they
may
be
operated
as
straight
ampli-
fiers
on
channels
2,3,
and
4.
With
the
function
selector
switch
in
the
"
l"
position,
the
VISUAL
CARRIER
DEVIA
TlON
m
eter
checks
visual
multi-
'·•1
plier
output
and
the
AURAL DEVIATION
meter
checks
aural
multiplier
output.
The
exact
multiplier
output
frequencies
for
a
par-
ticular
unit
are
given
on
a
label
attached
to
th
e
·
instrument
.
3-4
AURAL
MIXER
The
aural
mixer
(half
of
VS)
combines
the
aural
multiplie
r
output
and
the
AURAL
RF
INPUT
to
produ
ce
a
150-kc
difference
frequen
cy
if
the
trans-
mitter
is
on
frequency.
If
the
transmitter
is
above
its
assigned
frequency,
the
mixer
output
will
be
higher
than
1S0
kc.
If
the
transmitter
is
below
its
assign
ed
frequency
,
th
e
mixer
output
will
be
less
than
150
kc.
The
AURAL DEVIATION
meter
checks
the
AURAL
RF
INPUT
when
the
function
selector
switch
is
in
the
CARRIER
LEVEL
position
.
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Sect.
Ill
Page
2
3-5
AURAL
AMPLIFIER,
DISCRIMINATOR,
AND
DEVIATION
METER
Squaring
amplifiers
V6
through
V9
supply
a
push-
pull
square
wave
of
constant
amplitude
co
the
dis-
cnm
mator.
Current
regulator
Vl2
assures
con-
stant
output
amplitude
from
V9. .
The
pulse-counting
typ
e
discriminator
detects
audio
modulation
and
supplies
a
de
current
repre-
senting
average
transmitter
frequency
to
the
AURAL DEVIATION
meter.
Figure
3-2
is
a
si
mplifi
ed
diagram
of
the
discrimi-
nator
circuit.
With
the
transmitt
er
on
frequency,
the
150-kc
square
wave
is
differentiated,
rectified,
and
combined
with
the
bucking
current
from
R244
to
produce
a
zero
reading
on
the
AURAL DEVI-
ATION
meter.
If
the
transmitter
carrier
frequency
is
high, the
average
voltage
at
the
discriminator
output
is
more
negative
and
defl
ec
ts
the
AURAL
DEVIATION
meter
to
the
right.
If
transmitter
carrier
frequency
is
low,
the
average
voltage
at
the
discriminator
output
is
less
negative
and
de-
flects
the AURAL DEVIATION
meter
to
the
left.
The
audio
variations
at
the
dis
c
iminator
output
are
coupled
through
Tl
to
the
audio
amplifier
and
modulation
indicator
circuits.
JlJ7
r-1-r-½
Model
335E
3-6
AUDIO
CIRCUITS
AND
MODULATION
INDICATORS
Audio
amplifier
Vl0
is
a
stable,
low
distortion
audio
amplifier
with
negative
feedback
through
transformer
Tl.
The
input
to
cathode
follower
VllB
c
ontains
a
standard
75-microsecond
de-emphasis
netwoi;k.
A
high-impedance,
low-distortion,
unbalanc
ed
audio
output
can
be
obtained
between
terminals
4
and
5
of
TB201
if
the
link
b
etwee
n
terminals
3
and
4
is
removed.
A
balanc
ed
600-ohm
output
is
provided
at
terminals
1
and
2
of
TB201
with
the
short
ing
link
install
ed
betw
een
terminals
3
and
4.
Amplifier
and
ca
thode
follower
VllA
provides
isolation
between
the
peak
mod
u
lation
indicator
circuit
and
the
modulation
met
er
circuit.
The
metering
circ
uit
cons
ist
s
of
a
half-wave
rectifier
followed by a
network
which
damps
th
e
meter
in
accordance
with
FCC
requirements.
The
mec
\
ring
circuit
does
not
contain
a
de-emphasis
network.
\
The
MODULATION AURAL CARRIER
m
eter
th
erefo
re r
es
ponds
to
true
transmitter
modu-
lation,
regardless
of
modulation
frequency.
For
XFMR
Tl
AUDIO
TTm
AURAL
DEVIATION
METER
\
(
LOW-PASS
FILTER
AVERA
GE
DC:
-175MV
AT
153KC
-
9o
·
Mv
AT
150KC
OMV
AT
14
?KC
I
AVERAGE
DC:
-?GMV
AT
153KC
OMV
AT
ISOKC
+76MV
AT
147KC
+Dc
FROM---J\Arv
Vl2
R244
"c"
ADJUSTMENT S
ELECTS
BUCKING
CURRENT
TO
CENTER
METER
WITH
ISOKC INPUT.
Figur
e
3-2.
Simplified
Diagram
of
the
Discriminator
Circuit
..
e,
f\
www.SteamPoweredRadio.Com
Model
335E
the
same
reason,
the
modulation
meter
does
not
follow
VU
meters
in
the
audio
system
ahead
of
the
transmitter
pre-emphasis
network.
Audio
peaks
are
rectified
by
CR14
and
coupled
to
the
grid
of
thyratron
Vl
7.
When
the
input
voltage
to
Vl
7 eKceeds
the
triggering
level
selected
by
the
50%-120%
control
(R312),
the
thyratron
fires,
lighting
the
PEAKMODULATION INDICATOR
lamp.
Since
the
triggering
circuit
operates
quickly,
mod-
ulation
peaks
of
short
duration
may
cause
the
lamp
to
flash
when
the
modulation
shown
on
the
MODU-
LATION AURAL CARRIER
meter
is
onlya
fraction
of
that
selected
on
the
50%-120%
control.
3-7
VISUAL
MIXER
AND
4.3535-MC
OSCILLATOR/MIXER
The
visual
mixer
(half
of
V3)
combines
the
visual
multiplier
output
and
the
VISUAL
RF
INPUT
to
produce
a
difference
frequency
of
4.35
me.
The
VISUAL CARRIER DEVIATION
meter
checks
VIS-
UAL
RF
INPUT when th~ function
selector
switch
is
.
in
the
CARRIER
LEVEL
position.
Th.e
4.35-mc
output
of
the
visual
mixer
is
combined
in
the
mixer
portion
of
V4
with 4.3535
me
from
the
os~illator
portion
of
V4
to
produce
a
3.5-kc
dif-
ference
frequency.
The
VISUAL CARRIER DEVI-'
ATION
meter
checks
the
operationofthe4.3535-mc
oscillator
when
the
function
selector
switch
is
in
the
"2"
position,
Sect.
lII
Page
3
3-8
VISUAL AMPLIFIERS, DISCRIMINATORS,
AND
DEVIATION
MOER
The
3.5-kc
output
of
the
final
visual
mixer
is
passed
through
a
filter
(Zl-Z2)
which
eliminates
15,
750-cps
horizontal
sync
pulses.
Squaring
amplifiers
Vl3
through
VIS
supply
a
push-pull
square
wave
of
constant
amplitude
to
the
discrimi-
nator.
Current
regulator
VI6
assures
constant
output
amplitude
from
VIS.
The
pulse-counting
type
discriminator
supplies
a
de
current
representing
transmitter
frequency
of
the
VISUAL CARRIER DEVIATION
meter.
The
oper-
ation
of
this
discriminator
is
the
same
as
that
of
the
aural
discriminator
discussed
in
paragraph
3-5,
except
that
the
nominal
input
frequency
is
3.5
kc.
3-9
POWER
SUPPLY
A conventional
regulator
(Vl
9, V20, V21)
supplies
+ 300
volts
to
all
circuits.
Any
ac
component
(ripple)
on
the+
300-volt
line
is
minimized
by
feed-
back
through V22
to
control
tube
V20.
Constant-voltage
transformer
T3
supplies
filament
power
to
frequency-determining
circuits
and
V22
in
the
power
supply.
Crystal
oven
power
(TS)
is
not
controlled
by
POWER
switch
S4
.
The
crystal
ovens
operate
continuously
whenever
the
instrument
is
connected
to
a
power
line
.
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Sect.
IV
Page
0
TABLE
4-1.
RECOMMENDED
TEST
EQUIPMENT
FOR
COMPLETE
MAINTENANCE
Description
Example
Electronic
Voltmeter
1jfe
Mcxlel 410B
Sensitive
AC
Voltmeter
~
Model 400D
or
403A
Oscilloscope
~
Mcxlel
150
A
or
160B
Low-Distortion
Audio
Oscillator
1/jJ
Mcxlel 206A
Distortion
Analyzer
~
Mcxlel 330C
High-Frequency
Electronic
Counter
$
Mcxlel
524B/C/D
with 525A
(optional)
(if
M.O.
is
below 25
me)
or
Mcxlel
335E
525B
(if
M.O.
is
above
25
me)
.;
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