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VXR-5000
The CTC55 Tone audio level output is ad-
justed by VR2006 then delivered to Q2002-3
and the transmitter line input.
Modulated audio from the Rx unit is deliv-
ered to J2008-1 where it is fed through
inti
ext
audio select switch 52002 to Chebyshev Filter
Q2008-3
(NJM2902M)
and then high-pass fil-
tered by R2118 and R2146. The output is then
delivered to five-section, active HPF Q2008-1
which rejects audio frequencies below 300
Hz. 3-pole active LPF Q2006-3 rejects audio
frequencies above 3000 Hz.
Audio is de-emphasized by Q2006-2
(uPC4741G2)
and R2043
&
C2036, providing
flat audio response from 300 Hz - 3 kHz. The
filtered audio then passes through attenuator
52004 and LINE output level potentiometer
VR2003 to buffer amplifier Q2006-4
(uPC4741G2)
and impedance matching
transformer T2002 to LINE jack J2001 pins 1
&2.
Repeater Operation
Duplex Operation
The demodulated audio is delivered from the
RX unit to Q2008 and is high-pass filtered and
de-emphasized as described above. Repeater
"sensitivity" is adjusted using VR2005 before
delivery to Q2005
(uPC4741G2)
via repeater
switch 52001-3. When the repeater mute
switch Q2001-4 is closed, the gain of Q2005 is
reduced to 0, effectively muting repeater
audio. Repeater audio deviation is controlled
by potentiometer VR2004 before the signal is
delivered to audio amplifier Q2003-4, where
the signal is processed in the same manner as
previously described.
Intercom Function
Inserting a standard speaker
I
mic headset
into the
INTERCOM
jack 02010) provides
closed-loop audio for test! communications
with an installed remote base, for use by serv-
ice technicians. Inserting the headset into the
jack disables speaker audio via J2002, pins 1
&
2. Headset microphone audio is delivered
to buffer amplifiers Q2007-3 and Q2007-4
(both
NJM2902)
before application to line
audio selector Q2004.
2-4
Note!
If
using the optional YH-2 headset,
y~u c~n
connect into either the line or Tx/Rx ClrCUlts
for maintenance or testing.
Insert the
MIC/EAR
plug of the YH-2 into
J2009 on the CNTL-2 unit, then slide the
IN-
TERCOM
switch (S2003) to the desired posi-
tion:
NOR -
normal operation, the line is con-
nected to the Tx/Rx circuits.
TRCV -
the YH-2 is connected to the radio
Tx/Rx circuits, and the base station can be
keyed by pressing the blue PTT button on the
CNTL-l Unit.
LINE -
the YH-2 is connected to the line;
keying is not required.
Headset level is adjusted by
MON-LVL
(VR2007) on the CNTL-2 Unit. The default
setting is minimum (fully counter-clock-
wise). Note! - remember to set the switch at
NOR
for normal operation when the YH-2
is
removed.
Power Supply
The power supply includes the power
transformer and bridge rectifier D0002
(S25VB20)
on the chassis, a filter capacitor
bank on the CAPA Unit, and various regula-
tion and switching circuitry on the REG Unit.
AC power is applied to the primary of
TOOOI through fuse FHOOOI and relay
RLOOOI. The 16.5 VAC at the secondary is
then dual-fused by FH0002 and FH0003 be-
fore delivery to full-wave bridge rectifier
D0002 and the CAP A Unit.
The output of D0002 is then filtered by
capacitor bank C8501 and C8502 and the re-
sulting DC is applied to the collectors of
Q7002 and Q7004 (both
28018420)
on the
REG Unit, and regulator
Ie
Q70l3
(FMW1).
The control output of Q7103 is applied to the
base of Q7007
(2SB1134R),
the emitter of
which then controls the bases of Q7002 and
Q7004, thus highly regulating the voltages at
the emitters. This output voltage is then de-
livered through relay RL7001
(FBR631 0012)
and fuse FH7001 to supply the 13.5 VDC bus
for the rest of the repeater. A sample of the
13.5 VDC from the pass transistors is also
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