Revox B261 Serviceanleitung Seite 48

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8261 SA
sEcTroN
4/7
4.7.3 Adjusting the f5
kHz low-pass
filter
-
Connect
generator to test point MPl5, level Lv/35.2
kP^z
(moni,tor frequency with counter).
- connect
AF
voltmeter to
ourPUT
FrxED
L (R)
and
adjust L8 (L9)
for
maximum
voltage.
- Set generator to 23.5
kHz and
adjust LIO (L11) for
minimum
voltage.
4.7.4 Adjusting the f14 kHz rejection
- Connect generator through I nF capacitor to test point
MP16,
leveI 1V,/1I4 kHz.
- Short-circuit
R40
and connect base of Q2/R6 with ground.
- Connect AF voltmeter to test point l[Pl7 and adjust L3 for
min j,mum
voltage.
-
Remove
jumpers and disconnect generator.
4.7.5 Adjusting the 38 kHz cj-rcuit
- Feed 98.0 MHz, 40 kIJz deviati"on (modulation 1 kHz, Ieft
only)
without pilot tone signal from the stereo' standard-signal
generator into the antenna input.
- Connect oscilloscope
with probe (ext. trigger
on
OUTPUT
FIXED
R) to test point
MP16
and adjust L4 to welL-defined
envelope curve intersection.
4.7.6 Adjusti-ng the 19 kHz rejection
- Set stereo standard-signal
generator to 98.0 MFlz, 75
k}Jz
deviation,
modulatior: r kHz left
= right
with pilot
tone.
- Level at
OUTPUT
FIXED
L = approx. 2 V eff.
Switch modulation off.
- Adjust L5 to
minimum
voltage and adjust balance on
OUTPUT
FIXED
L and
R.
4.7.7 Adjusting the I kHz cross-taIk rejection
- Set stereo standard-signal
generator to 98.0 MHz, 40
kRz
deviation,
modul-ation f kHz, left = right
with prlot
tone
ci,,h11
- Connect audio voftmeter to
OUTPUT
FIXED
L and calibrate to
0
dB.
- llodulate only right-hand channel of stereo modulator.
- Adjust for
maximum
cross-talk rejection
(> 43 dB) wi.th
R4.