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(3)
Connect
the
input(s) for
electronic timing.
For single line
timing
connect
the external signals
to
Input
'B'.
For
double
line
connect
the
'start'
line to
'B'
and
the
'stop'
line
to
'A'.
(4)
Press
the
Timebase
(n)
button
which
provides
the
appropriate
readout.
In
the
9906 an
I.e.d.
will
indicate the
units of
the
display.
(5)
For
manual
timing
press
the
START/STOP
push-button,
as
required.
(6)
If
operating on
HOLD
press
and
release the
RESET
button
to initiate
a
new
(non-manual)
timing process.
RATIO
n
A
B
4.9
In this
mode, two
unknown
signals
are fed
to inputs 'A'
and
'B'.
Generally
the higher
frequency
is
fed vio 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
A
and
the
reading must
be
divided by
the factor
'n'
to
obtain the
ratio n
A
B
B
Ratio
Operation
Set the
POWER
switch
to
ON.
Set the
following
controls:-
(a)
The
FUNCTION
switch
to
RATIO
n-^.
b
(b)
The
AC/ DC
switches
to
AC
or
DC
as
appropriate.
(c)
CHECI^OPERAT^HOLD
switch
to
OPERATE.
(d)
DELAY
switch
to
OUT.
Connect
the input signals
to
sockets
'A'
and
'B'.
(See para.
4.9
above)
.
Press
the
Timebase
(n)
button
which
gives a
full
display
without
overspill
.
If
on
AC
adjust the
SENSITIVITY
control as
necessary.
9902
&
9906
Vol
.
1
4-4
(6)
If
on
HOLD
press
the
RESET
button
for
a
new
reading.
(7)
To
obtain the
true ratio
the displayed reading must
be divided by
the factor
'n'
indicated
above
the selected
Timebase
button.
TOTALIZE
^
n
4.1
1
In
this
mode,
signals
on
input
socket
'A'
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
socket
'B'.
This
mode
permits
a
number
of
events occurring with
random
timing
to
be counted over
a
chosen
period.
(1)
Set the
POWER
switch
to
ON
and
other controls
as
follows:-
(a)
The
Function switch
to
TOTAL
A.
n
(b)
The
'A'
channel
AC/DC
switch
as
required.
(c)
The
CHECK/OPERAT^HOLD
switch
to
OPERATE.
(d)
The
DELAY
switch as required.
(e)
The
START
and
STOP
slope switches
to
select the required
trigger
edge
polarities.
(2)
Connect
the signal
to
be
totalized
to
socket
'A'
and
the electrical
timing
signals
(if
used)
to
socket
'B'
.
(3)
Press
the
Range
push-button
which
will
provide
suitable units
for
the
count.
For
example,
if
the
10^
button
is
depressed the display
will
be
in units
of
1000
(within the
accuracy
of
measurement).
NOTE:
If
the
range
n
=
1
is
used a count
of
1
will
be displayed
when
the
main
gate opens.
(4)
If
operating on
HOLD,
press
and
release the
RESET
button before
taking a reading.
(5)
If
manual
control
is
being used
press the
START/STOP
button
to
commence
counting
and again
to
terminate counting.
The
display
will
be held
for
about
four
seconds before automatically clearing.
(6)
In
order
to
obtain thp
true total
the displayed reading
must
be
multiplied
by
the scaling factor
'n'
Indicated
above
the selected
Range
button.
9902
&
9906 Vol
.
1
4-5
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