Axcera INNOVATOR, Инструкция по эксплуатации

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UHF Analog Driver/Transmitter/ Chapter 4, Circuit Descriptions
Translator
LX Series, Rev. 3 4-7
for offset and precise frequency 45.74 or
45.76 MHz, connects to the board.
The external IF CW Input connects at
J41A pin 32A and is connected to J19 and
through the external cable assembly W10
back to the board at J20. The external IF
CW input is split on the board. One
branch connects through C157 to a
buffer amplifier Q20 to the K2 relay at
pin 14. The other path is through C152
to the amplifier U23A. The output of
U23A is split with one part connecting to
Q26 that shuts down the 45.75 MHz
oscillator. Another path connects to Q25
the conducts and lights the LED DS7,
Alternate IF, viewed on the front panel.
The final path connects through R268 to
Q22 that is biased on and energizes the
relay, K2. The external IF CW Input at
contact 14 now connects through the
closed contact to the splitter network
consisting of L31 and L32.
Either the internal or external CW IF from
the K2 relay is split with one path
through L31 to the amplifier U28 to the L
input of Z1 the Aural IF Mixer. The other
path is through L32 to the amplifier U29
to the L input of Z2 the Visual IF Mixer.
4.2.1.11 Visual Modulator Circuit
The video signal is heterodyned in mixer
Z2 with the visual IF CW signal (45.75
MHz). The visual IF CW signal from L32
of the splitter connects to U29, where it
is amplified and wired to pin 1, the L
input of mixer Z2. Adjustable capacitor
C168 and resistor R275 are set up to add
a small amount of incidental carrier
phase modulation (ICPM) correction to
the output of the mixer stage to
compensate for any non-linearities
generated by the mixer.
The modulated 45.75 MHz RF output of
mixer Z2, at pin 4 the R output, is
amplified by U30 and is fed to J17
through W8, the external cable
assembly, “WB”, to J13 on the board.
J17 is the visual IF loop-through output
jack that is normally jumpered to J13 on
the board. The modulated visual IF
through J13 connects to J41C pin 17C the
Visual IF Output of the board.
4.2.1.12 Aural Modulator Circuit
The mixer Z1 heterodynes the aural-
modulated 4.5 MHz signal with the 45.75
MHz IF CW signal to produce the
modulated 41.25-MHz aural IF signal. The
audio modulated 4.5 MHz from the 4.5
MHz VCO IC U16 connects, “J”, to the I
input at pin 5 of Z1. The visual IF CW
signal from L31 of the splitter connects to
U28, where it is amplified and wired to pin
1, the L input of mixer Z1. The R output of
the mixer at pin 4 is fed to a bandpass
filter, consisting of L18-L21, L25-L28 and
C136, C137 and C142-144, that is tuned to
pass only the modulated 41.25-MHz aural
IF signal. The filtered 41.25 MHz is fed to
the amplifier U27. The amplified 41.25
MHz signal is connected by a coaxial cable,
W9, from J21, “WC”, to J18 on the board.
The modulated 41.25 MHz aural IF signal
from J18 is connected to J41C pin 6C, the
Aural IF Output of the board.
4.2.1.13 Combining the 45.75 MHz Visual
IF and 41.25 MHz Aural IF Signals
The Visual IF connects back to the board at
J41C pin 3C, through a Visual IF jumper
cable connected to the rear chassis of the
exciter/driver. IF processing equipment
can be connected in place of the jumper if
needed. The visual IF is connected to J12,
through jumper W7, “WA”, to J14. The
visual IF is amplified by U24 and filtered by
FL1 with T1 and T2 providing isolation.
The filtered IF is amplified by U25 and
adjusted in level by R214 before it is
connected to a summing circuit at the
common connection of L16 and L17.
The Aural IF connects back to the board at
J41C pin 23C, through an Aural IF jumper
cable connected to the rear chassis of the
exciter/driver. IF processing equipment
can be connected in place of the jumper if
needed. The aural IF, “F”, is connected
through C132, R234, R235 and adjusted in
level by R243 before it is connected to a