Receiver Components; Hf/If Unit; Hf/If Components - Loewe Q2500B Serviceanleitung

Technology of Q 2500 colour TV set

3 Receiver components

3.1 HF/IF unit

Four receive components can be used in de-
vices with Q 2500 chassis. One is the terres-
trial tuner, or HF/IF component, which proc-
esses frequencies from 47 MHz to 860 MHz.
This hyperband tuner is located on the basic
board.
Second is the single SAT or dual SAT receiver
for the first IF from 950 MHz to 2150 MHz.
This is partly a standard feature or can be
retrofitted for certain sets.
In addition, for full IP sets a PIP-HF/IF unit for
the reception of terrestrial signals is incorpo-
rated into the hyperband range. In this case,
however, the audio band is dispensed with, as
picture for picture only video signals are re-
quired. This is also built into the basic board.
With this equipment the set is able to process
all television signals, irrespective of whether
they are received by terrestrial antennae or
via cable units, and even when derived from
parabolic antennae.
Document Q 2500
3.1.1

HF/IF components

A HF/IF combination is also used. All func-
tions for current European television stan-
dards are located in one housing, with two
provisos. The IF consists of only one picture
IF. The audio demodulation takes place in the
audio IC on the signal board. From the IF
component only the sound IF is supplied as
broadband.
This means that the ceramic transducer and
an expensive sound/IF switch are not re-
quired. Secondly, for lower price models not
destined for export HF-IF, designed only for
PAL and SECAM BG, is used. In this case,
the change-over to SECAM L and NTSC and
the components necessary for this are not
required.
This means the two designs are hardware and
software compatible.
The following block circuit diagram shows the
multi-standard design. Some of the compo-
nents are not fitted to the BG version.
As in earlier models, the electronics is housed
in an HF proof folding housing.
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