Revox A76 Service Manual

S3.
I
mage
response
Test
equipment:
Signal
generator,
frequency 87.5
MHz,
2
ptV o.c.v.
modu-
lated with
stereo
modulator,
15
kHz
deviation,
modulating
frequency 1
kHz,
no
pilot
frequency.
Distortion
analyzer
or audio
millivoltmeter.
5.3.1.
Tuner:
Power switch
depressed
Set
dial
pointer to 87.5
MHz
mark (
left hand
stop
),
fine
tune to
obtain zero
indication
on the
CENTRE TUNING
meter
(44).
5.3.2.
Calibrate
distortion
analyzer
or
millivoltmeter to
obtain
a
reference reading.
5
.
3.
3.
Turn
off
modulation,
measure
noise voltage and keep
a
note of the
reading obtained
( ratio
must
exceed
30
dB).
5
. 3. 4.
Adjust
frequency and
signal
generator to 109
MHz ( that
is
the
previous
test frequency
of
87.5
MHz plus
twice
the IF,
which equals 21.4
MHz).
Increase
output level to 100
mV o.c.v.,
fine
adjust fre-
quency
to
obtain zero reading
on the
CENTRE TUNING
meter
( 44
).
5
. 3
. 5
.
Lower output
level
until a
noise
voltage
(
as noted
under
5.3.3.
)
is reached
(
better
than
30
dB).
Image
response
performance
is
within
specifications
when
this noise value
is
reached
with an output
level
of
12
mV
o.c.v.
or higher.
(
I
mage
response 76
dB).
5.4.
Spurious
response
Test
equipment:
Signal
generator, frequency 94
MHz,
2
juV
o.c.v.,
modulated
with
stereo
modulator, 15
kHz
deviation,
modulating
fre-
quency
1 kHz, no pilot
frequency.
Distortion
analyzer (or audio
millivoltmeter).
5.4.1.
Tuner:
Power
switch
depressed.
Adjust
output
frequency
on generator
to obtain zero reading
on
CENTRE
TUNING
meter
(44)
(approx.
94
MHz).
5.4.2.
Calibrate
distortion
analyzer or millivoltmeter
to
obtain a
reference
reading.
5.4.3.
Turn
off modulation, measure
noise
voltage
and
keep
a
note
of the reading
obtained (
ratio
must exceed
30
dB
).
5.4.4.
Adjust
output
frequency on generator
to
88.65
MHz ( that
is the
previous test
frequency of
94
MHz minus 5.35
MHz),
raise output level
to
100
mV o.c.v.
fine
adjust
frequency
to obtain zero
reading
on CENTRE
TUNING
meter
(44).
5.4.5.
Reduce
output level
until
a
noise voltage
as
noted
under 5.4.3.
is
reached
(
better
than
30
dB).
The
tuners
spurious
response
is
within
specifications
when this
noise value
is
reached
with
a
output
level
of
60
mV o.c.v.
or higher
(spurious
response
90
dB).
20

Revox A76 Specifications

General

Brand	Revox
Model	A76
Category	Tuner
Language	English