VXR-SOOO
17.
TONE
OFF
Logic
Input (Active
Low)
This
input
is internally
pulled
up
to 5-V
DC.
When
pulled
low
by
an
external de-
vice,
it
disables the internal CTCSS de-
coder
(if enabled). The internal CTCSS
encoder section is
not
affected
by
this in-
put.
Use this
input
when
channel monitor-
ing
with
squelch action is required (e.g.
tone
monitor
function). Voltage
in
excess
of 5
V
on
this
pin
may
damage
the CPU
on
the repeater CNTL-1 Unit.
18.
TX
Logic
Ouput (Active
Low)
This open-collector logic
output
is pulled
low
when
the
transmitter is activated.
It
can
sink approx. 100
mAo
The signal on
this
pin
is always true
when
the transmit-
ter is on.
It
is
intended
to
be
used
where
an
"ON-AIR" indication is required.
19.
AUDIO
MUTE
Logic
Input (Active
Low)
This
input
is internally
pulled
up
to
5-V
DC.
When
pulled
low
by
an
external de-
vice, it disables receiver
output
to pins 5 &
6 of the
modular
LINE jack.
In
the
RE-
PEATER mode, the repeat
audio
is
not
af-
fected
by
signals
on
this pin. Avoid voltage
in
excess of 5 V
on
this
pin
or
internal
damage to
the
CPU
on
the
repeater CNTL-
1
Unit
may
result.
20.
SQ
LOW
Logic
Input (Active
Low)
This
input
is internally
pulled
up
to
5-
V
DC.
When
pulled
low
by
an
external de-
vice it selects
the
low squelch mode.
In
low
squelch
mode,
the
hysteresis
between
squelch
open
and
closed is only 3
dB
(in-
stead
of
the
normal 6 dB). The squelch
closing level is unchanged.
The absolute squelch closing level is set
by
VR4001
on
the
RX
Unit. For example,
if
the
squelch
on
the
RX
Unit
has
been set to
open
at
-110 dBm
in
normal
mode, then
1-14
with
the
sa
LOW
pin
grounded,
the
squelch will
now
open
at
about
-113 dBm.
In
either case, the squelch will close
at
-116
dBm. Avoid voltage
in
excess
of
5 V
on
this
pin, which could
damage
the
CPU
on
the
repeater CNTL-1
Unit.
21,22 & 23.
REMOTE
DO,
DI
&
D2
Logic
Inputs
(Active
Low)
These inputs
are
internally
pulled
up
to
5-
V DC.
When
pulled
low
by
an
external
device, they select
one
of
the
eight
pre-pro-
grammed
repeater
operating
channels.
The logic
truth
table below
shows
the
com-
binations for selecting all 8 channels.
In the
truth
table,
"I"
represents
no
con-
nection,
and
"0" represents a
ground
con-
nection
on
the pin.
The channel selection logic is
not
inhibited
while
the
transmitter is keyed:
the
repeater
will change frequency
when
instructed,
even while transmitting.
Avoid voltage
in
excess of 5 V
on
these
pins or internal
damage
to
the
CPU
on
the
repeater CNTL-1
Unit
may
result.
VXR-5000 Channel Access
(DO-D2, pins
21,22
& 23)
CH
02
01
DO
1 1 1
1
2 1 1 0
3 1 0 1
4 1 0
0
5 0 1
1
6
0
1
0
7
0 0
1
8 0
0 0
24
&
25.
RST
+ &
RST-
Logic
Inputs
An
opto-isolated RESET
input
is
pro-
vided between
pins
24
and
25. A voltage of
between 3
and
15
V resets
the
repeater
microprocessor.
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