Becker europa TR, Service Manual

Page: 7 / 45

iff a capacitive precipices the collector is of
T 202 at the oscillator circuit. The collector supply voltage wi rd through R 217 (47 ohms) T 202 at the oscillator circuit. The collector supply voltage wi rd through R 217 (47 ohms)
fed. The oscillator vibrates in three-point circuit. The series inductor L 215 is used
for narrowing the variation range, R 218 (33 ohms) to the oscillator variometer L
for narrowing the variation range, R 218 (33 ohms) to the oscillator variometer L
216 linearizes the parallel resonant voltage over the areas. LW to the MW-OS
216 linearizes the parallel resonant voltage over the areas. LW to the MW-OS
zillator inductors (L 215, L 216) is connected the series coil L 218th The parallel
inductor L 217 is required to obtain a smooth running in LW. The oscillator
capacity wi rd in the LW range around 239 C (10/60 pF) + C 240 (440 pF)
increases. In KW-operation wi rd the inductances L 215, L 216, L 214 additionally
switched on as a parallel coil circuit capacitance as the capacitors of the divider
233 C (350 pF), C 234 (600 pF) are Merely effective.
c) IF gain c) IF gain
The following IF amplifier is 2-stage constructed
(T 203 and T 204). It contains the band filters F 202, F 204 and the individual
circuit L 225. The coupling of the low-basis via a respective capacitive divider ven.
The transistor T 203 is regulated. T 204 wi rd not regulated, so that it distort large
signal amplitudes can handle rungsarm.
d) Demodulation and control d) Demodulation and control
Signal and control means are concerned by the diode Di 206, which is inductively
coupled to the arrival last IF circuit. The resistors R 236 (3.3 ohms) + R 235 (6.8
coupled to the arrival last IF circuit. The resistors R 236 (3.3 ohms) + R 235 (6.8
ohms) form the load resistor. The NF is taken at R 235 (6.8 ohms) and supplied to
ohms) form the load resistor. The NF is taken at R 235 (6.8 ohms) and supplied to
the volume control over C3 (0.1 microfarads). Through the resistors R 235 (6.8 ohms),
the volume control over C3 (0.1 microfarads). Through the resistors R 235 (6.8 ohms),
R 236 (3.3 ohms) and R 230 (18 ohms) receives the base of the first transistor T
R 236 (3.3 ohms) and R 230 (18 ohms) receives the base of the first transistor T
203 IF part of the stabilized through the diode Di 207 voltage as voltage
Grundvorspan-. The voltage drop across R 234 (390 Ω) biases diode Di 206 in Flow
Grundvorspan-. The voltage drop across R 234 (390 Ω) biases diode Di 206 in Flow Grundvorspan-. The voltage drop across R 234 (390 Ω) biases diode Di 206 in Flow
direction before, thereby improving demodulators lation and
Demodulationsverzerrungen be Ringert comparable.
The in demodulation on the load resistor R 236 (3.3 ohms), R 235 (6.8 ohms) The in demodulation on the load resistor R 236 (3.3 ohms), R 235 (6.8 ohms)
resulting DC voltage is used for automatic uses gain control and R 230 (18 ohms),
resulting DC voltage is used for automatic uses gain control and R 230 (18 ohms), resulting DC voltage is used for automatic uses gain control and R 230 (18 ohms),
R 225 (2.7 ohms) and R 219 (1 ohms) placed on the base of T 203rd The resulting
voltage diode clamping the basic prestress is opposed coupled ver thus a signal at
the incident Ringert the effective base bias of T 203. By thus verbun dene
lowering of the collector or emitter current will consequently the slope and thus the Gain
lowering of the collector or emitter current will consequently the slope and thus the Gain
reduced. The emitter resistor R 222 (2.2 ohms) ent stationary voltage drop is used
reduced. The emitter resistor R 222 (2.2 ohms) ent stationary voltage drop is used
for regulation of the pre-stage transistor T two hundred and first fal Since
transmission means l, the emitter current of T drops 203, the base bias of T 201
low, which also corresponds to a slope control of this transistor. the out Stabilization
low, which also corresponds to a slope control of this transistor. the out Stabilization
reasons absolutely necessary emitter resistor R 205 (2.2 ohms) now exerts a
reasons absolutely necessary emitter resistor R 205 (2.2 ohms) now exerts a reasons absolutely necessary emitter resistor R 205 (2.2 ohms) now exerts a
disadvantageous gen impact on the regulation since it any type of emitter current
change, so therefore also compensated by the control desired stabilizing effect.
This effect is the diode Di 201 in conjunction with the divider R 206 (680 Ω), R 207
This effect is the diode Di 201 in conjunction with the divider R 206 (680 Ω), R 207
(5.6 opposed ohms). In unge regulated state of the input transistor, the diode is
blocked, ie the measured against "inner Plus" clamping voltage drop at the emitter
branch R 205 (2.2 ohms) is greater than that from the divider 206 R (680 Ω), R 207
branch R 205 (2.2 ohms) is greater than that from the divider 206 R (680 Ω), R 207 branch R 205 (2.2 ohms) is greater than that from the divider 206 R (680 Ω), R 207
(5.6 ohms) Festge withstand voltage. In this operating case undergoes the
(5.6 ohms) Festge withstand voltage. In this operating case undergoes the
transistor T 201 not influenced in its temperature stability through the diode
branch. however, Wi rd T 201 turned down, the emitter potential falls below
soon a value at which the diode Di opens wi 201 rd. This means for further down
rules that the precursor transistor wi tung kept almost constant Emitterschal- rd,
on which it has been switched on by diode Di 201 overall. So that the unwanted
DC negative feedback is canceled. Each additional increase of the RF input
voltage controls the level down further effective because changes in the control
voltage now vol l become effective on the base-emitter junction. In extreme cases,
the base potential of the emitter may up to even slightly positive, because the
emitter voltage of the controlled IF stage 203 to zero T
running. this chip
voltage also represents the control voltage for the transit sistor T two hundred and
first exceeded the down-regulated state
the control voltage, the temperature stabilization.
2. FM area
The FM input signal travels from the antenna via the AM-FM switch to the input of the
transformer Tr. 101. The input circuit formed with the secondary side of this
transformer is strongly attenuated and by the low input impedance of the pre-stage
transistor T 101 tuned to mid-band. In the collector branch of the transistor Lie
precursor gene by variometer (L 101) and a tunable intermediate circuit with the
voltage drop across R 102 (150 Ω) preloaded Damping diode Di 101, which prevents an
voltage drop across R 102 (150 Ω) preloaded Damping diode Di 101, which prevents an voltage drop across R 102 (150 Ω) preloaded Damping diode Di 101, which prevents an
overdriving the mixing stage for large input signals comparable.
via the capacitor C 109 (4 pF), the amplified input signal reaches the emitter of the
self-oscillating mixer stage 102. The T
inductively tunable oscillator circuit loading
protrudes from the variometer L 102 and the circuit capacitance, Ge forms the trimmer
C 114 (3/10 pF) and the series connection of C 115 (18 pF) and C 116 (39 pF). The
feed- back a part of the oscillating voltage is done via C 113 (4 pF) to the emitter.
While the oscillator circuit to a capacitive Abgri the collector of the mixing stage ff is
the first 10.7 MHz IF circuit is performed fully on this transistor. That means:
for the oscillator frequency affects the IF
Coil as a high impedance choke through which the collector receives the operating
voltage. For the IF frequency, however, the relatively low-variometer coil L 102 is
parallel to the capacitors C 115 (18 pF) and C 116 (39 pF) to ground. The input and
output capacities,
in particular the
Oscillator and mixer transistor, are very dependent on the collector emitter voltage tor.
Therefore, the operating voltage by means of zener diode Di 208 was stabilized, the Di
to 208 connected in parallel electrolytic capacitor C 264 (50 uF) may seventh possible
low-frequency disturbances from the UK operating voltage. The IF voltage of the coil L
wi rd taken inductively 103 and the first filter F 101 supplied to the IF amplifier through
a coupling line (link line).
The subsequent amplification of the 10.7 MHz IF via four stages. The stages are
coupled via the bandpass filter F 202, F 203 and F 204 together. Al l IF stages are
neutralized, for reasons of stability. On the primary side of the filter 203 F wi rd
removed via C 225 (10 pF), a part of the ZF-voltage and in a chip
nungsverdopplerschaltung means of the diodes Di 202 and Di 203 used for generating
a control voltage. Via the resistor R 106 (2.2 ohms) reaches the control voltage
a control voltage. Via the resistor R 106 (2.2 ohms) reaches the control voltage
clamping the base of the input transistor. If the demodulation of the IF signal
sym in the
trically constructed Ratio Filter F 205. Mi t means of the regulator R 241
(potentiometer. lin 3 kOhm.) can be possible tolerances in the ratio load resistors and
(potentiometer. lin 3 kOhm.) can be possible tolerances in the ratio load resistors and
diodes compensate. The NF-signal passes through the deemphasis member R 240
(8.2 ohms), C 265 (68 nF), and is then about 3 C (0.1 uF) on Lautstärkereg- ler P. 1
(8.2 ohms), C 265 (68 nF), and is then about 3 C (0.1 uF) on Lautstärkereg- ler P. 1 (8.2 ohms), C 265 (68 nF), and is then about 3 C (0.1 uF) on Lautstärkereg- ler P. 1
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