Ratio; Totalize - Racal Instruments 9901 Maintenance Manual

RATIO
ny
2.9
In this
mode, two unknown
signals
are fed
to inputs 'A'
and
'B'.
Generally
the
higher frequency
is
fed via input socket
'A' to
the counter
decades and
the lower frequency
is
fed through input socket
'B'
to the
time-base decades, but
this
input
arrangement
may
be
reversed,
as for
example,
when
the
lower frequency has a smaller
amplitude
(e.g. 10
mV) and
the
higher frequency a considerably
larger
amplitude. The
display indicates the ratio n
A
and
the reading must be
divided
by
the factor
'n'
to
obtain
the ratio
A
.
B
B
Ratio
Operation
2.10
(
1
)
(2)
(3)
(4)
(5)
(6)
TOTALIZE
-
II
Theoretical Considerations
2.11
In
Totalize
mode,
signals
on
the 'A'
input socket are prescaled
and
taken
to
the counter decades. The count can be
controlled
manually by
the
START/
STOP
button or
electrically
by
timing
signals
connected
to the
' B'
input socket.
This
mode
permits a
number
of events occurring with random
timing
to
be counted
over
a
chosen period.
A
counter time base
in
Totalize
mode
is
generally designed
to reset to either
0
or
9; in
either
case a rounding
off
of the
count occurs
to
an accuracy
of
±
1
count,
as
shown
in
the
following
table.
It
may
be noted
that the Racal counters (9901
,
9903
,qnd
9^5)
reset to 9.
No.
of
i/p pulses
(n
=
10^
selected)
Counter Display
t/b
tfeset
9
t/b
teset
0
Error
Reset
9
Reset
0
1 1
0 0.999
0.001
999
1
0
0.001
0.999
1000
1
1
0 0
*
See
NOTE
on page
2-5.
Set the
POWER
switch
to
ON.
Set the following
controls:
-
(a)
The
FUNCTION
switch
to
RATIO
n
^
D
(b)
The
AC/DC
switch, the Pulse/Contact
switch
and
HOLD/
NORMAL
switch
set
as required.
Connect
the
input
signals to
sockets
'A'
and
'B'
.
(See para 2.9).
Press
the
Range
button
which
gives a
full
display without
overspill.
If
operating
on
HOLD
press
and
release the
RESET
button
for
a
new
reading.
If
on
'AC
adjust the
SENSITIVITY
control as necessary.
To obtain the
true ratio the displayed reading must
be
divided by
the
factor
'n'
indicated
above
the selected Range
button.
9901 Vol.
2.
2-4