Akai VS-2EGN

8-1 DISTRIBUTING/COMBINING
The distributor/combiner circuit is as shown in Fig. 7-
115.
When a 75 © load is applied to outputs 1 and 2, the im-
pedance viewed from the input side becomes 752, and
the signal can be distributed without any matching loss.
Combining is just the reverse, and impedance viewed
from each of the output terminals 1 and 2 is designed to
be 75Q, without any transmission between them.
8-2 LPF AND HPF
U/V ANT
OUTPUT 1
INPUT R
OUTPUT 2
Fig. 7-115 Distributor/Combiner Circuit
LPF
VHF
DIVIDER
UHF
DIVIDER
FROM
RF CONVERTE!
The distributor/combiner circuit is shown in Fig. 7-
Tuner) terminals are provided with a LPF (VHF) and a
HPF (UHF) respectively to prevent VHF output and
9. RF CONVERTER FUNCTIONS AND CIRCUITS
The RF converter is for modulating video and audio sig-
nals to obtain an RF signal within the TV UHF Band
between channels 30 and 39, in the case of PAL
SECAM.
iv.
VIDEO INO
RF OUT
© (To TV SET)
© TUNER OUT
TO BUILTIN
TV TUNER
Z
Fig. 7-116 Filters
UHF output from being affected by presence of the
UHF amp and VHF amp respectively. Refer to Fig. 7-
116.
The circuit will be described with reference to Fig. 7-113
(B). The actual RF converter circuit is an IC except for
the carrier oscillator and the balanced modulator. The
operation in the IC is described in the section dealing
with the discrete circuit.
> TO VIDEO
MODULATOR
FROM AUDIO
MODULATOR
Fig. 7-117 Clamp Circuit
9-1 CLAMP CIRCUIT
The clamp circuit is for regulating the leading edge of
the SYNC signal which is the reference level of modu-
lation to be used as a fixed level before the input video
signal is modulated. By applying the voltage split pro-
Service Manual VS-2EGN
vided by R2 and R3 to the base of transistor TRI via
D1, the leading edge of the SYNC signal is clamped to
this voltage. TR1 is the emitter follower. The level of
video/audio signal to be fed to the modulator is adjust-
ed by RS and R6,
81