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(12)
Operate
the
distortion
analyzer
so that the
scope
displays the input to the distortion
analyzer.
Reduce
analyzer
sensitivity
until
no overload
occurs.
With
scope
in
NORMAL
TRIGGER
mode,
adjust
TRIGGER
LEVEL
until
sweep
barely
shuts
off.
(13)
As you
did with the
broadband
limiter
test
in
step
8,
alternately
connect and
remove
the hot
lead
from
the oscillator,
while observing
the
scope
as
it
triggers
on
the
overshoot from the
high-frequency
limiter.
Adjust
P209
(high-frequency FET
bias)
until
the
scope
displays a single-shot pattern
like
FIG.
3
with the scope time base adjusted
for
1
ms/cm.
HIGH
FREQUENCY
LIMITER
ATTACK
(5
kHz
—
no
signal to 10
dB
gain reduction)
(5V/cm;
1
mS/cm)
FIGURE
3
(14)
Connect
the distortion
analyzer
to fork terminal
^5
(and
readjust
the oscilloscope
triggering so that the
distortion signal
can
be
viewed).
Measure
the har-
monic
distortion.
Reduce
the
level
of the oscillator
until
the
distortion
is
maximum.
Adjust
P208
(right
h.
f.
distortion null) to
minimize
THD.
(15)
Connect
the oscillator to
the
LEFT
AUDIO
INPUT
and
repeat
step 14,
connecting
the
distortion
ana-
lyzer
to
the
left
channel
h.
f.
limiter
output (termi-
nal 2),
and
adjusting
P207
(left
h.
f.
distortion null)
for
minimum
distortion.
This
concludes the alignment procedure.
APPENDIX
B:
SPECIFICATIONS
INPUT:
Impedance: 150
k
ohms
balanced;
active
differential input.
Level:
-10
dBm
produces 10
dB
gain reduction with
jnpjut
attenuator
fully
clockwise.
Absolute
input
overload occurs
at
+
21
dBm.
OUTPUT:
Impedance:
less
than
400 ohms,
unbalanced.
Level:
+ 4
dBm
nominal
with output attenuator
full
clockwise.
Peak
level
approximately
+
12
dBm.
y
FREQUENCY
RESPONSE:
±
0.5
dB, 20-20,000
Hz
below
high-frequency
limiter
threshold.
HIGH-FREQUENCY
LIMITER:
Controls high-frequency
peaks attempting
to
exceed a
threshold defined
by a
single-time-
constant
rolloff
of 75, 50, 37.5, or
25
microseconds,
±3%.
Rolloffs
are switch
selectable
from
front
panel,
and
high-frequency
limiter
is
defeated
in "flat"
position.
Attack Time: approximately 3
milliseconds.
Release Time:
varies
around 15
milliseconds
according
to
program
history.
Control Element: junction
field-effect
transistor
BROADBAND
LIMITER:
Attack Time:
1
to
2
milliseconds.
Release Time: Program-controlled by
means
of
quadruple time-constant
release
time
analog
processor.
Release time
may
be
scaled
fast
or
slow by
means
of
continuously
variable
Release
Time
control available
to user.
Range
of
Gain
Reduction: greater
than 15 dB.
Compression
Ratio:
in
excess
of
200:1
Interchannel Tracking:
±
1.5
dB
max.; 1
1
dB
typ.
Control Element:
junction
field-effect
transistor
SEPARATION:
50
dB
or
better,
20-20,000
Hz.
NOISE
(dB below
limiting
threshold
at
100
Hz;
20-20,000
Hz
bandwidth):
-80
dB
typ.;
-75
dB
max.
TOTAL
HARMONIC
DISTORTION:
(See graph)
Ibtai
Harmonic Dmortion
(<M>)
OPERATING CONTROLS:
OUTPUT ATTENUATOR
(left
and
right
ganged)
INPUT
ATTENUATOR
(left
and
right
ganged)
RELEASE
TIME
H-F
LIMITER
TIME
CONSTANT
75
uS;
50
uS; 37.5 uS;
25
uS;
flat
METER SELECTOR
left
input; right input;
left
output; right output;
gain
reduction;
-f
15
volt
power
supply;
-15
volt
power
supply
AC
UNE
OFF/ON
INDICATORS:
AC
POWER
PILOT
LAMP
OVERLOAD
(tights
if
attempt
is
made
to
exceed
possible
broadband
AGC
range)
METER
[3.5" (8.9
cm)
with
VU
"A"
scale
and
characteristics]
POWER
REQUIREMENT:
115/230
VAC ±
10
%;
50-60
Hz,
approximately 6
watts.
U-ground power
cord
attached.
DIMENSIONS:
19" (48.3
cm)
wide
x
3.5"
(8.9
cm)
high
x
10"
(25.4
cm)
deep.
OPERATING TEMPERATURE
RANGE:
0-50°
C.
WARRANTY:
1
year, parts
and
labor.
Subject
to limitations
set
forth
in
our standard
warranty agreement.
9
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