TFT 730A User manual
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SECTION
1
SECTION
2
SECTION
3
TABLE
OF
CONTENTS
GENERAL
INFORMATI
ON
Page
1.
1
Gene
ra1
De
sc
ri
pt
i
on
. . . ••. •. . ••. . . . . . . •. • 1-1
1.2
Specifications
..••
•.
.....
..••
. •
......•..
1-1
1.3 Accessory
Equipment
..
••..•
•.
•••
•••••••
•• 1-4
1.3.1
Model
704B
Remote
Meter
and
Peak
Flasher••.
•••.
..•..
.•.•
•.•
.
...
1-4
1. 4
Warranty
...
....
..
. .
.....
.
..
.
..
.
..
.
....
..
1-5
1.5
Claims
for
Damage
in Shipment•• .
•..•....
1-5
INSTALLATION
2.1
Unpacking
and
Inspection
••.
.•
.
..
••
•.••..
2-1
2.2
Power
Requirements
•••
...•...•.•..••
••••
• 2-1
2.3
Installation
With
the
Model
763
.••
.
•...
• 2-1
2.4
Model
704B
Remote
Readout Panel
Connection (Optional)
...•.•..•
•••
..
2-1
2.5 Subcarrier-Off
Alann
Connection
...
•.
.•
.•
2-2
OPERATION
3.1
3.2
3.2.1
3.2.2
3.3
3.4
3. 5
3.6
3.7
3.7.1
3.7.2
3.8
3.9
3.10
3.11
3.12
General
.
..
...
.
.......
....
.
...
.......
.
..
. 3-1
Controls, Connectors,
and
Indicators
.
.•.•
•. •••
...•..••
.
.••
•
..
3-1
Front
Panel
•.
. .
.•
••
••
••.
•
...•
. ••. ••••
•.
.
3-1
Rear Panel.
..
. . . . .
...........
...
......
..
3-4
Turn-On
and
Wann-Up
.•
••.••.•..••.••.
••
.•
3-6
Main
Channel
Calibration
•••
•.•
. ••• •
••••
• 3-7
SCA
Injection
Calibration••
•••
•
•••
•••• •• 3-7
SCA
Modulation C
alibration
...•..••.••
. •. 3-7
Measurement
of
SCAModulation
and
Main
Channel
Modulation
Using
the
Modulation Meter
•••
•
•.•••
3-8
SCA
Modulation•• .
..•
•••.•••..
•
.••••
•
••..
3-8
Main
Channel
Modulation•• . •••••••
•••••
. . 3-8
Measurement
of
SCA
Modulation
Using
the
Peak
Flashers
.••..•
•
••..•
3-8
Measurement
of
S
CA
Injection
Using
the Modulation Meter
•••.•
•. •• 3-9
Audio
Output. .
..
.
..•..
. •
..••••.
..
.
.....
• 3-9
Subcarrier-Off
Alann
.
...
.••
.•
...•.••.••
• 3-9
Model
704B
Remote
Readout Panel
(Optional)
..
•
.•.
••
.••.•.•
•
..
•
.•.•
••. .•
•.
3-10
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SECTION
3
SECTION
4
SECTION
5
SECTION
6
TABLE
OF
CONTENTS
(Continued)
OPERATION
(Continued)
Page
3.13
Using
the
Wideband
Input
for
SCA
3.13.1
3.13.2
3.13.3
Measurements
.....•.•••••....•..••.•
3-10
Calibration
of
Wideband
Input
Level
.•..•.•...•..•••••••••••.•..••
3-10
Reading
SCA
Injection
with the
Broadband
Input
...••.••..•..•••••.•
3-10
Reading
SCA
Modulation with the
Wideband
Input
••.••••.••.•••••.••.•
3-10
THEORY
OF
OPERATION
4.1 General
Block
Diagram
4.1.1
4.1.2
4.1.3
4.1.4
Discussion
.•..•..•.••.•..•••••••.••
4-1
Main
Channel
Monitoring
•.•.•••••.•.•••••
4-1
SCA
Injection
Monitoring
•.••••••.•.••.••
4-2
SCA
Modulation Monitoring
•.•.•..•••••...
4-2
Calibration
Circuits
•.•...••.••..•.•...•
4-3
MAINTENANCE
5.1
5.2
5.3
5.4
5.5
5.6
5.7
5.7.
1
5.7.2
5.7.3
5.7.4
General
••••.•...•.••••.•.•...•••••.••.••
5-1
Access. . •••. . . •. •. •. •. ••••••. . . . ••. •. •.•
5-1
Periodic Maintenance
••.•..•..•..•..••.••
5-1
Main
Channel
Modulation Accuracy
Check
•• 5-1
SCA
Injection
Accuracy
Check
.•••••.•••••
5-2
SCA
Modulation
Accuracy
Check
•..•••••...
5-3
Troubleshooting Guides.
••••••
•..•••.•..•
5-4
Instrument does not
work
in
any
mode
Main
Channel
(L&R)
does
not work, but
SCA
Injection
and
modulation
do
work
SCA
Injection
does not work, but
main
channel
(L&R)
does
work
SCA
Modulation does not
work
but
SCA
Injection
does
SCHEMATIC
DIAGRAMS
6.1
Block
Diagram
6.2 Front Panel
and
Chassis
Wiring
6.3 Rear Panel
Wiring
6.4
Meter
Amp
Board
(Al)
6.5 Discriminator
Board
(A2)
6.6
Mixer
I.F.
Board
(A3)
6.7
Power
Supply &
Main
Channel
Amplifier
(A4)
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SECTION
1
GENERAL
INFORMATION
General Description.
The
Model
730A
SCA
Monitor
nonna
l
ly
is
used in
conjunction with the
Model
763
FM
Modulation Monitor to monitor the
characteristics
of
the
SCA
transmission in
FM
broadcasting.
It
can also
be used for recovering the
SCA
information in the composite signal used
in
FM
broadcasting.
The
Model
730A
measures
SCA
injection
level,
SCA
modulation percentage,
SCA
FM
signal
-to-noise
ratio
,
and
crosstalk
. T
he
desired function
is
selected
by
front-panel pushbutton
sw
itches. A
six-
position,
pushbutton-selectable precision
attenuator
is
also
provided
for
use in
making
these measurements.
SCA
injection
and
SCA
modulation
are
indicated
by
a front-panel meter.
SCA
subcarrier
frequency can
be
measured
by
the
six-digit
counter
on
the
Model
764
or
an
external
counter.
The
Model
730A
can monitor
either
of
two
SCA
carrier
frequencies
--
41
kHz
or
67
kHz
--
selectable
by
front-panel pushbutton
switches. Other
SCA
frequencies
are
available
on
special orders. Also,
either
+ 4
kHz
or
+ 6
kHz
can
be
selected
by
front
-panel pushbutton
switches-as the deviation
that
represents
100%
modulation.
1.2
Other
features
of
the
Model
730A
include:
0
0
0
Digital ly
settable
peak
modulation
flashers
that
display
positive
and
negative peaks simultaneously.
Built-in
calibration
circuits
for meter
and
peak
flashers.
Outputs
for
Model
7048
Remote
Meter
and
Peak
Flasher
panel
and
SCA
subcarrier
alarm.
Specifications.
SCA
Subcarr
ier
Frequency
41
kHz
and/or
67
kHz,
pushbutton
selectable
SCA
Fregu·
ency
Measurement
The
selected
SCA
signal
is
filtered
and
returned
to
the
frequency counter input
of
the
Model
764
FM
Presel
ector
and
displayed
on
the
6-digit
digital
readout.
Signal Input Requirement
Accepts composite signal
from
Model
763
, 0.5 V
RMS
for
100%
modulation reading.
1-1
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1.2
(Continued).
Main
Channel Modulation measurement
Deviation
for
100%
......•.....••••.••.•..
Modulation Accuracy,
50
Hz
to
15
kHz
•
•...
Out
of
Band
Rejection,
20
kHz
to
75
kHz
••
+75
kHz
+4%
56
dB
SCA
Injection
Accuracy
(30%
to
1%)
....
•
.•..•.•....
.•
•
•.
+0.si
SCA
Subchannel Modulation
Measurement
Meter
Deviation
for
100%
.••.••.•.•••..•..••.•.•
Carrier
Frequencies
#1
.••••...•.•.•••..•.•••••••.••••••••••••
#2
•••••••••••••••••••••••••••••••••••••••
+4
kHz
or
+6
kHz
67
kHz
(standard)
41
kHz
(optional)
Modulation Accuracy
(OdB
Meter Attenuator Switch Position)
@1
kHz,
100%. •
••••
•••
•••••
••
••
•••••••
•
•••
+2
%
Frequency Response
Composite
Inp
ut
20
Hz
to
6
kHz
..•
••
•..•••
•••••••
••••
20
Hz
to
7.5
kHz
•
•••
.
••••••
.•••
•••
••
Wide
band
Input
20
Hz
to
7.5
kHz
.•.•••••.•....•.•••.
Selectivity
(Composite Input)
Narrow
+ldB
+2dB
+0
.5
dB
BW,
3
dB
••••••••••••••••••••••••••••
BW,
60
dB
••••.•••••••••••••••..••.••
3
kzH
(typical)
20
kHz
(maximum)
Wide
BW,
3
dB
•••
•..•
••••••.
•
•.
••••..•••••
BW,
60
dB
••••.••••••••••.•..••••.•••
20
kHz
(typical)
60
kHz
(maximum)
Scal e
Range
.•
.•
•.•••..•
.•••
•
•••••••••••
••
Attenuator
Range
••
•..••
••..•••
•
•••••
•
•••
•
1-2
o
to
40%,
O
to
133
% (-2
dB
to+
2
dB)
0
to
-50
dB
in
10
dB
steps
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1.2
(Continued).
Crosstalk Rejection (Composite Input)
Main
Channel
(50
Hz
to
15
kHz)
into
SCA
Subchannel
{Narrow)................
66
dB
Stereo
(23
kHz
to
53
kHz,
excluding subhannonics
of
SCA
Subchannel)
into
SCA
Subchannel
(
#1
,
Narrow)
......................
.
SCA
Subchannel
into
Main
Channel
•....•..
66
dB
66
dB
SCA
Peak
Modulation
Indicator
Range
•
..•.••.••.•••.•
.
••
.•
..•.....•.•.••
50
%
to
129
%
Resolution
.••.••
•
...•.•.....•••.•.•..••
.
Accuracy.
.•.....•........•.....•..•..
•..
+10
%
Response
Time
••••.
.••
••
.•.
•••
••••••
••••• 1 cycle
of
2
kHz
SCA
Modulation
and
Injection
Level
Calibrator
Outputs
Built-in
modulation
and
injection
level
calibrator
for
calibrating
the modulation meter
and
the
positive
and
negative
peak
flashers
from
the
front
panel.
SCA
Subcarrier
Level,
at
10
%
SCA
Injection
•••.••.•
SCA
Subcarrier
Alarm
.•.••••....••••...••
500
mV,
nomi
na
1
into
5K
ohms
Contact closure
when
subcarrier
is
below
muting
1
evel
Audio
(with
or
without de-emphasis, 75/150 u sec)
Level
(600
ohms),
100%
modulation,
400
Hz
nominal...
....
................
2 V
RMS
(8.2
dBm)
Distortion
Composite input
+6
kHz
at
400
Hz.
.......
.
1.5%
+4
kHz
at
400
Hz.........
1%
Wideband
input
+6
kHz
at
400
Hz.........
0.5%
1-
3
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1.2
(Continued).
Power
Noise Level,
relative
to 6
kHz
deviation (with de-emphasis)
Composite Input,
or
Wideband
Input.
R.F. Input
at
10
mv
••••.•••••••••••
115/230 _
~10%
VAC,
50
to
400
Hz,
25
watts
maximum
Physical
and
Environmental
Operating Temperature
••••••••.•.•••••••
•
.•.••
Size
.
...............................
.
.......
.
Wei
g
ht
•
••.•.•..•..••••••••.•..•.•.•.•••••.•..
Accessory Equipment
-66
dB
-55
dB
7"
high x
19"
wide
x 16"
deep
Approx.
15
lbs.
1.3
1.3.
1
Model
704B
Remote
Meter
and
Peak
Flasher
Panel.
Duplicates meter
and
peak
flasher
readings
of
the
Model
730A.
Fifty
feet
of
cable
and
plug provided.
1-4
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1.4 Warranty.
TIME
&
FREQUENCY
TECHNOLOGY
,
INC.,
warrants each
of
the
instruments
of
its
manufacture to
be
produced
to
meet the
specifications
delivered
to
the
BUYER;
and
to
be
free
from
defects in material
and
workmanship
and
will
repair
or
replace,
at
its
expense,
for
a period of
one
year
from
the date
of
delivery
of
equipment,
any
parts
which
are
defective
from
faulty
material or poor
workmanship
.
Instruments
found
to
be
defective during the warranty
period shall
be
returned to the factory with
transportation
charges
prepaid
by
BUYER.
It
is
expressly agreed
that
replacement
and
repair
shall
be
the
sole
remedy
of
BUYER
with respect
to
any
nonconforming
equipment
and
parts
thereof
and
shall
be
in
lieu
of
any
other
remedy
available
by
applicable
law.
All
returns
to
the factory
must
be
authorized
by
the
SELLER,
prior
to
such
returns.
Upon
examination
by
the
factory,
if
the insturment
is
found
to
be
defective,
the
unit
will
be
repaired
and
returned
to
the
BUYER,
with
transportation
charges
prepaid
by
SELL
ER
.
Transportation charges
for
instruments
found
to
be
defective within the
first
thrity
(30)
days
of
the warranty period will
be
paid both
ways
by
the
SELLER.
Transportation charges
for
warranty
returns,
wherein
failure
is
found not
to
be
the
fault
of
the
SELLER,
shall
be
paid both
ways
by
the
BUYER.
This warranty does not apply
to
instruments which, in the
opinion
of
the
SELLER,
have
been
altered
or
misused.
NO
OTHER
WARRANTY
IS
EXPRESSED
OR
IMPLIED.
TFT
IS
NOT
LIABLE
FOR
CONSEQUENTIAL
DAMAGES.
1.5
Claim
for
Damage
in Shipment.
Your
instrument should
be
inspe
cte
d
and
tested
as
soon
as
it
is
received.
The
instrument
is
insured
for
safe
delivery.
If
the
instrument
is
damaged
in
any
way
or
fails
to
operate properly,
file
a
claim with the
carrier,
or
if
insured
separately,
with the insurance
company
.
WE
SINCERELY
PLEDGE
OUR
IMMEDIATE
AND
FULLEST
COOPERATION
TO
ALL
USERS
OF
OUR
PRECISION
ELECTRONICS
INSTRUMENTS.
PLEASE
ADVISE
US
IF
WE
CAN
ASSIST
YOU
IN
ANY
MANNER.
Time
&Frequency Technology, Inc.
3000
Ol
cott
Street
Santa C
lara
,
CA
95051
408-246-6365
1-5
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2.1
SECTION
2
INSTALLATION
Unpacking
and
Inspection.
Upon
receiving the instrument,
inspect
the packing
box
and
instrument
for
signs
of
possible shipping
damage.
Operate
the
instrument
in
accordance with the procedures
of
Section 3
of
this
manual.
If
the
instrument
is
damaged
or
fails
to operate properly,
file
a claim with
the
transportation
company,
or with the insurance
company
if
insured
separately.
2.2
source;
The
line
required
2.3
2.4
Power
Requirements.
The
Model
730A
normally operates
from
a
115
volt
AC
if
it
is
wired
for
230
volts,
the
line
cord will
be
so
marked.
frequency
must
be
between
50
and
400
Hz
.
Maximum
power
is
25
watts.
Installation
With
the
Model
763.
a.
Mount
the
Mode
l
730A
in the equipment rack.
NOTE
If
the
Model
730
is
not
mounted
in a
common
rack
with the
Mode
l 763, a ground wire of
18
AWG
or
larger
must
be
connected between the
two
chassis.
b.
Connect one
of
the
furnished coaxial cables between
COMPOSITE
INPUT
connector
Jl
on
the
rear
panel
of
the
Model
730A
and
SCA
MONITOR
OUTPUT
connector J6
on
the
rear
panel of the
Mode
l 763.
c.
Connect
the
other
coaxial cable between
SUB-CARRIER
FREQUENCY
connector J4
on
the
rear
pane
l of the
Model
730A
and
SCA
CARR
connector J13
on
the
rear
panel
of
the
FM
Preselector.
Model
7048
Remote
Readout Panel
Co
nn
ection
(Optional).
When
a
Model
704B
is
to
be
used
with
the
Model
730A,
connect the five-wire cable
of
the
Model
704B
to
terminals
a,
C,
D,
E,
and
G
of
terminal
strip
J7
on
the
rear
panel of the
Model
730.
The
wire
color
code
is
given in Section
3.2.2
of
this
manual
under Reference
No.
10.
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2. 5 Subcarrier-Off
Alarm
Connection.
Connect the external alarm device to
SCA
SUBCARRIER
ALARM
banana
jacks
J2
and
J3
on
the
Model
730A
rear
panel. These
jacks
are
shorted together
when
the
SCA
subcarrier
level drops below
the
threshold
set
by
the
SCA
MUTE
LEVEL
control
R39
on
Board
A2
(see Section
3.11).
Neither
one
of
the
jacks
is
grounded
in
the
Model
730.
Maximum
power-
handling
capability
is
1.0
ampere
at
115
V
AC.
2-2
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3.1 General
SECTION
3
OP
ERATION
The
Model
73OA
SCA
Monitor
is
used in conjunction with
the
Model
763
FM
Modulation Monitor to monitor the
SCA
subcarrier
from
an
FM
broadcast
transmitter.
SCA
injection
level,
SCA
modulation
percentage,
SCA
FM
signal-to-noise
ratio,
and
crosstalk
can
be
measured
on
the
front-panel meter.
No
external equipment except the
Model
763
is
needed
for
calibrating
the
meter.
3.2
3.2.1
Fig.
3-1
Ref.
No.
1
2
3.
4
5
6
7
Contro
ls
, Connectors,
and
Indicators.
Front Panel.
Name
FLASHER
CAL
control
PWR
switch
MAIN
CHAN
switch
SCA
INJ
switch
SCA
MOD
switch
SCA
SUBCHANNEL
#1
switch
SCA
SUBCHANNEL
#2
switch
3-1
Used
peak
3
.6)
mode.
Function
in
calibrating
the
flasher
(see Section
in
SCA
Modulation
When
depressed, energizes
the
instrument.
When
depressed, meter
indicates
main-channel modulation.
10
%
represents
+
75
kHz
FM
deviation. -
When
depressed, meter
indicates
SCA
injection
level.
100%
=
+75
kHz
deviation.
When
depressed, meter
indicates
modulation of the
SCA
subcarrier.
This switch
is
depressed
for
monitoring a
67
kHz
subcarrier.
Th
i s switch
is
depressed
for
monitoring a
41
kHz
subcarrier
(Optional).
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3.2.1
Fig. 3
-1
Ref.
NO.
8
9
10
11
12
13
14
15
16
17
(Continued).
Name
NARROW
SELECTIVITY
switch
WIDE
SELECTIVITY
switch
+4
kHz
switch
+6
kHz
switch
METER
CAL
sw
itc
h
METER
"+"
switch
METER
II II
switch
SCA
INJ
CAL
control
SCA
MOD
CAL
control
Modulati
on
meter
3-2
Function
When
depressed, provides a
3-
dB
bandwidth
of
3
kHz
and
a
60-dB
bandwidth
of
20
kHz.
When
depressed, provides a
3-dB
bandwidth
of
20
kHz.
When
depressed, meter
indicates
100
%for
an
FM
deviation
of
+4
kHz
on
SCA
subcarrier.
When
depressed, meter
indicates
100
%
for
an
FM
deviation
of
+6
kHz
on
SCA
subcarrier.
When
depressed, allows
calibration
of
all
three
modes
of
operation:
Main
Channel,
SCA
Injection,
and
SCA
Modulation.
When
calibrating
the
main
channel (composite
level adjustment),
the
Calibrate
switch
on
the
763
must
also
be
depressed (see Sections
3.4
, 3.5,
and
3.6).
When
depressed, meter reads
positive
SCA
or
Main
Channel
modulation peaks.
When
depressed, meter reads
negative
SCA
or
Main
Channel
modulation peaks.
Used
in
SCA
injection
calibration
(see Section 3
.6
).
Used
in
calibration
3.
6).
SCA
modulation
(see Section
Reads
modulation
and
injection
1evel , both
in
percent
and
in
dB
above
and
below
100%.
Either
positive
or
negative
modulation peaks will
be
indicated, depending
on
whether
the
METER
11
+
11
or
METER
11
-
11
switch
is
depressed.
When
the
100
%
METER
ATTENUATOR
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3.2.1
Fig.
3-1
Ref.
No.
18
(Continued).
Name
METE
R
ATTENUATOR
switches
3-3
Function
switch
is
depressed,
the
meter reads
directly;
when
any
other
attenuator
switch
is
depressed,
the
scale
factor
of
the
selected
switch
must
be
applied.
Depressing
one
of
these
switches changes the gain
marked
thereon in the modulation
meter
circuit.
The
resulting
measurement
is
the algebraic
sum
of
the meter reading
and
the
inserted
attenuation.
For example, a meter
indication
of
-2
dB
with the -30
dB
switch depressed
would
indicate
a measurement
of
-
32
dB
below
100
%modulation. Three
of
the switches are
marked
1%,
10%
,
and
100
%. These
indi
cate
the actual modulation
percentage
when
the meter
needle
is
at
the
100
%
mark.
For example, a meter reading
of
70
% with the 1%switch
depressed
would
indicate
a
measurement
of
0.7%
modulation.
When
in the 0
-dB
position,
the
switch
selects
the
output
of
the
peak
detector
on
the Meter
Amp
Board
Al
to
drive the
MODULATION
METER.
When
in
any
other
position,
the
switch
selects
the
output
of
the average
detector
on
the Meter
Amp
Board
to drive a
MODULATION
METER.
When
the
730
is
operating
in the
SCA
MODULATION
mode,
any
setting
of the
METER
ATTENUATOR
setting
except
"OdB"
wi
11
switch a
75
u
sec
or
150
u sec,
(selectable
by
means
of
an
internal
jumper),
int
o the audio
www.SteamPoweredRadio.Com
3.2.1
Fig.
3-1
Ref.
No.
19
20
3.2.2
Fig. 3-2
Ref.
No.
1
2
(Continued)
Name
SCA
SUBCARRIER
indicator
PEAK
MODULATION
Rear Panel.
Name
COMPOSITE
INPUT
Connector J1
COMPOSITE
LEVEL
SET
Control
R2
3-4
Function
output
circuitry
of
the
Discriminator
Board
A2
so
that
the
SCA
modulation delivered to
the Meter
Amp
Board
Al
is
de-emphasized.
When
the switch
is
in the
OdB
position
the de-
emphasis network
is
switched
out
of
the
circuit.
Lights
when
the
SCA
subcarrier
is
present
(i.e
.,
when
the
SCA
subcarrier
level
is
above the threshold
set
by
the
SCA
MUTE
LEVEL
control)
.
The
switches
set
the
peak
modulation percentage
at
which
the
indicators
will
flash.
The
indicators
flash
when
the modulation
peaks exceed the
setting
of
the switches: the
+
indicator
for
positive
modulation pe~ks
and
the - i
ndi
ca
tor
for
negative peaks.
Function
Provides
means
for introducing
a composite signal
from
the
Model
763.
Used
to
adjust
level
of
incoming composite
signal
from
the
Model
763
. (See Section 3.4,
3.5
,
and
3.
6)
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3.2.2
Fig. 3-2
Ref
.
No
.
3
4
5
6
7
8
9
(Continued).
Name
SCA
SUBCARRIER
AL
ARM
Connectors
J2
and
J 3
WIDEBAND
INPUT
LEVEL
R6
WIDEBAND
INPUT
J9
SCA
SUBCARRIER
connector
J4
AUDIO
OUTPUT
connector
JS
AUDIO
OUTPUT
connector
J6
lA
SLO
BLO
fuse
3-5
Function
When
the
SCA
subcarrier
level drops
below
the
level
set
by
the
SCA
MUTE
LEVEL
control,
these
two
connectors
are
shorted together
by
an
internal relay
to
operate
an
external
alarm.
Adjusts level
of
incoming
SCA
signal for the
WIDEBAND
INPUT
.
Provides
an
input
which
bypasses the
I.F.
filtering,
thus providing
desireable
modulation
characteristics
such as
flatter
frequency
response
and
lower
distortion.
Can
be
used
when
the
SCA
signal alone
is
injected
onto the
main
carrier.
Provides
SCA
subcarrier
frequency output.
Delivers the recovered
SCA
audio signal without
de-emphasis. Output
is
2
volts
RMS
for
100%
modulation.
Delivers a recovered
SCA
audio output
from
the
de
-emphasis network.
Level
is
2
volts
RMS
for
100%
SCA
modulation
at
400
Hz
.
Fuses the
AC
power
circuit.
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3.2.2
Fig. 3-2
Ref.
No.
10
11
3.3
(Continued).
Name
115
VAC
line
cord
Tenninal
strip
J8
Tu
rn-On
and
Warm-Up
.
Function
For connecting the Monitor
to
a
power
source.
If
the Monitor
is
wired
for
230V
input, the
line
cord will
be
so
marked.
Provides the following
outputs:
A:
The
same
voltage
that
operates the modulation
meter,
to
operate the
Model
7048
Remote
Readout
Panel. Connect
7048
red wire.
C:
The
same
voltage
that
operates the
front
-
panel
+
PEAK
MODULATION
indicator,
for
operating
the corresponding
indicator
on
the
Model
7048
brown
wire.
D:
Ground.
Connect
7048
black wire.
E:
The
same
voltage
that
operates the
front-
panel-PEAK
MODULATION
indicator,
for
operating
the corresponding
indicator
on
the
Model
704B
Remote
Readout Panel.
Connect
704B
white wire.
G:
+5
V
DC.
Connect
the
7048
green wire.
Make
sure the
Model
730A
is
cabled
to
other equipment
as
described in Section 2.
Check
the
line
cord
to
make
sure the
Model
730A
3-6
www.SteamPoweredRadio.Com
3.3
(Continued).
is
wired
for
the
line
voltage to
be
used (115
or
230
volts).
Plug
the
line
cord
into
the
power
source
and
press the
PWR
switch. Since the
Model
730A
is
a completely
solid-state
instrument,
warm-up
time
is
very
minimal.
One
or
two
minutes should
be
more
than adequate
to
provide
consistent
readings.
3.4
3.5
3.6
Main
Channel
Calibration.
a. Depress the
MAIN
CHAN
switch.
b. Depress the
METER
CAL
switch.
c. Depress
the
OdB
METER
ATTENUATOR
switch.
d.
On
the
Model
763,
press
the
CAL
switch.
e.
Adjust the rear-panel
COMPOSITE
LEVEL
SET
control
for
a
100%
reading
on
the meter.
SCA
Injection
Calibration.
a.
Depress
the
METER
CAL
switch.
b.
Depress
either
the
WIDE
or
NARROW
SELECTIVITY
switch.
c.
Depress the
SCA
!NJ
MEASURE/CAL
switch.
d. Depress the
-20
dB
METER
ATTENUATOR
switch.
e.
Adjust the
SCA
!NJ
CAL
control
for
a meter reading
of
100%
(10%
injection
).
SCA
Modulation
Calibration
.
a.
Depress
the
OdB
METER
ATTENUATOR
switch.
b. Depress
the
SCA
MOD
MEASURE/CAL
switch.
c.
Depress
the
+6
kHz switch.
-
d. Adjust
the
SCA
MOD
CAL
control
for
a meter reading
of
100%.
e.
Set
Peak
Modulation
Thumbwheel
switches
for
100%
and
adjust
FLASHER
CAL
POT
so
that
flashers
just
come
on.
3-7
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PAGE
3-7
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