Ramsey Electronics COM 3 User Manual

43 FREQUENCY COUNTER DIRECT
CONNECTION
The
Com
3
can
be
used
as
an
RF
frequency
counter
by
connecting
a
50
Q
probe
or
sniffer
loop
to
the
RF
input.
This
is
useful
for
the
alignment
of
crystal
oscillators.
1)
Connect
a
50Q
probe
or
sniffer
loop
to
the
RF
INPUT.
2)
Bring
the
loop
close
to
the
oscillator,
or
connect
the
probe
to
an
appropriate
test
point.
The
Com
3
will
display
the
frequency
in
MHz.
4.4 FREQUENCY/DEVIATION
MEASUREMENTS
The
following
series
of
tests
will
allow
the
measurement
of
the
frequency
and
deviation,
of
the
transmitter,
and
the
PL
tone.
NOTE:
We
will
assume
that
the
transmitter
is
300
Hz
low
in
frequency,
has
deviation
of
7.4KHz,
the
PL
tone
deviation
is
1KHz,
and
the
frequency
of
the
tone
is
high
by
5.0
Hz.
4.4.1 TRANSMITTER FREQUENCY
MEASUREMENT
1)
Connect
the
whip
antenna
to
the
RF
INPUT
jack.
2)
Enter
in
464.15,
then
touch
the
MONITOR
FM
key.
3)
Connect
the
tranceiver
to
be
tested
to
an
antenna
or
dummy
load.((DO
NOT
under
any
circumstances
connect
a
transmitter
to
the
RF
INPUT
of
the
Com3,
serious
damage
will
result.)
4) Touch the. FREQUENCY key, and two red
lights
will
light,
one
on
each
side
of
the
(1.5KHz)bargraph
display.
Touch
the
FREQUENCY
key
again
and
the
(7.0
KHz)
range
is
selected.
Key
the
transmitter,
note
that
only
the
center
LED
is
lit.
5)
Touch
the
FREQUENCY
key
to
select
the
(1.5
KHz
range).
The
first
two
LEDs
from
center
on
the
minus
side
of
the
scale
should
be
lit,
indicating
that
the
transmitter
frequency
is
300
Hz
low.
Adjust
the
transmitter
until
only
the
center
LED
is
lit.
The
transmitter
is
now
exactly
on
464.150
MHz.
42
4.4.2 CTS TONE FREQUENCY
MEASUREMENT
1)
Connect
the
whip
antenna
to
the
RF
INPUT
jack.
2)
Enter
in
-
464.15,
then
touch
the
MONITOR
FM
key
and
the
deviation
key.
`
3)
Connect
the
tranceiver
to
be
tested
to
an
antenna
or
dummy
load.
(DO
NOT
under
any
circumstances
connect
a
transmitter
to
the
RF
INPUT
ofthe
Com
3,
serious
damage
will
result.)
4)
Key
the
transmitter,
(mute
the
microphone
50
no
voice
or
background
noise
will
disturb
the
measurement).
If
too
much
background
noise
or
voice
is
present,
the
frequency
display
will
say
(Error).The
amount
of
background
noise
can
be
observed
on
the
deviation
bargraph
display
(1.5KHZ.range).
Touch
the
AF
COUNT
key,
the
display
should
indicate
the
CTS
tone
frequency
immediatly.
For
our
example
our
tone
should
be
82.5
Hz,
since
it
is
high
by
5.0
Hz
the
display
will
read
87.5
Hz.
Adjust
the
CTS
tone
frequency
until
82.5
Hz
is
displayed.
|
NOTE
If
the
transmitter
is
turned
on
after
entering
the
AF
COUNT
mode,
you
may
notice
an
8
to
10
second
wait
before
the
frequency
display
can
stabilize.
De-
select
and
re-select
the
AF
COUNT
mode
by
touching
the
AF
COUNT
key
twice.The
display
should
stabilize,unless
the
signal
is
too
weak
or
. noisy.
4.4.3 CTS TONE DEVIATION -
" MEASUREMENT
1) Connect the whip antenna to the RF
INPUT jack.
2) Enter in 464.15, then touch the MONITOR
FM key.
| 3) Connectthe tranceiverto be testedto an
antenna or dummy load. (DO NOT under any
circumstances connect a transmitter to the RF
INPUT
of
the
Com-
3,
serious
damage
will
result.)
4)
Touch
the
AF
COUNT
key
to
select
the
AF
COUNT
mode.

Ramsey Electronics COM 3 Specifications

General

Brand	Ramsey Electronics
Model	COM 3
Category	Monitor
Language	English