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d.
CAL pushbutton AlS7 provides a
modulation calibrate
.;~
. signal.
The frequency
this signal is 32KHz.
Section 5 for further
information.
NOTE:
lO UNLOCK led must light when
CAL is
depressed.
9.
Display (Vector and Spectrum Analyzer)
NOTE:
To use these features of the 691
res an oscilloscope
wi
X
and
V
DC Coupled inputs.
The bandwidth of
scope need only be a
few hundred kTTohertz but
it
must
DC Coupled on both X and Y inputs.
a.
Connect VERT (AIJ3)
Scope Y input.
Connect HORIZ (AIJ4)
to Scope
X
input. Set both inputs to DC coupled, 0.5 vol
/div.
b.
To
ew Stereo Vector pattern, depress VECTOR
on AlS4B.
Mono modulation will
ve a vertical line.
Any deviation from vertical in-
dicates that the
on mono balance
is
incorrect.
c.
To use Spectrum Analyzer
, depress NARROW pushbutton
on AIS4B.
Adjust
horiz. (X) gain
get full width baseline. Adjust
vert
(V)
gain to O.5/div.
Dis ay will
centered on
de-
termined by CARRIER FREQUENCY swi
and will be approximately
and
10dS/div.
Depressing WIDE pushbutton will change dispersion to approximately
+350KHz.
NOTE:
WIDE position will cause TOTAL MODULATION displ
to pin
-
and peak flasher
if
is OFF.
10.
PILOT PRESENT indicator A1DS3 and 0AOJ AIR! indicate the presence
of the
pilot tone and provide monitor
calibration in conjunction
with
0
posi
on of CHANNEL B DISPLAY SELECT.
lot
0
ADJ AIRl is set
for a null on CHANNEL B meter.
This adjustment is accurate even with modu-
lation appli
11.
SeA PRESENT indicator AIDS4 indicates the presence of SCA.
DEV
switch A1S9 may be set to cause CHANNEL
B
SCA MOD
spl
to indica
100% at ei
4KHz
or
6KHz
dev;
on.
12.
FREQ Jack AIJ5 and switch AIS8 provide a conveni
output for an
external counter to read station frequency, pilot frequency or SeA frequency.
To read station
requires a counter capable
lO.7MHz.
First con-
the counter to
XO jack on the rear panel.
If the
X.D.
;s not exactly
8.000000MHz, adjust
piston trimmer on the monitor A2 as
y until it
See Section 5
details.
Now
the counter to A1J5 and place
to IF position.
counter should
1O.7MHz.
If
it
lower.
station frequency is higher by the same number of hertz.
Conversely.
if
reads hi her, the s
ion frequency is lower.
NOTE: .=.B.=.e--=...::..:....:;:.-::..:..-..,:=
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