PacComm TINY-2 - Page 143

TROUBLESHOOTING
Other
symptoms
Uncopyable
received
packets
If
some
but
not
ail
packets
are
copied,
set
the
command
MCOM
ON.
Many
packet
transmissions
are
control
frames
and
contain
no
printable
information.
MCOM
will
cause
these
frames
to
be
displayed.
Confirm
proper
wiring
of
the
radio
cable
by
opening
the
radio
squelch
and
taising
the
volume
level
with
some
type
of
signal
tuned
in.
If
the
DCD
LED
flickers
or
solidly
illuminates
then
receiver
audio
is
reaching
the
packet
controller
modem.
Test
the
modem
by
performing
an
audio
loopback.
If
the
test
fails,
perform
a
digital
loopback
to
be
sure
the
problem
is
really
in
the
modem
section.
Listen
to
the
audio
signal
from
the
radio
applied
to
the
packet
controller
or
examine
the
signal
with
a
scope
for
hum
or
other
noise
which
might
make
the
packet
signals
uncopyable.
Confirm
the
proper
level
of
the
audio
signal
is
applied
to
the
packet
controller
with
a
digital
meter
or
scope.
DCD
LED
flickers
excessively
or
stays
on
If
the
DCD
LED
flickers
on
and
off
excessively
or
remains
constantly
on
only
with
the
signal
cable
connected,
be
sure
the
radio
is
operating
with
squelch
closed,
that
shielded
signal
cable
is
being
used,
and
that
the
audio
drive
level
from
the
radio
is
not
excessive.
If
audio
is
being
obtained
from
a
speaker
output
or
other
low
impedance
output,
place
a
jumper
on
JPR
located
near
R12.
If
high
impedance
audio
is
being
used,
JPR
should
be
off.
If
these
areas
all
check
out,
consider
changing
the
value
of
resistor
R10
to
a
lower
value
between
10
and
100
chms.
Transmitter
locks
in
transmit
condition
99
The
TINY-2/MICRO-2
is
protected
against
PTT
matfunction
by
a
watchdog
timer
on
the
keying
line.
However,
if
unshielded,
improperly
grounded
cabling
is
used
to
feed
the
transmitter
key
line,
and
other
signal
cables,
RF
energy
can
get
back
into
the
packet
controller
and
lock
up
the
keying
transistor.
Precautions
are
especially
necessary
if
a
high
power
amplifier
is
being
used
and
there
is
a
strong
RF
field
in
the
area
of
the
packet
controlfer.
TINY-2/MICRO-2
Technical
Ref.,
2
Ed
©
1989,
PacComm,
Inc.