Description Of Controls - Racal Instruments 9901 Maintenance Manual

DESCRIPTION
OF CONTROLS
Function Push-Button Switch Bonk:
This
bonk
of
seven push button switches,
located near the centre of the
front
panel,
select the following
measurement modes:-
(i)
TJ,
Provides
time interval
measurement between
two
successive events.
The
events
may
be on
one
line
(B-B) or separate
lines
(B-A), with
start
and stop slopes of the
same
or
opposite
polarity.
(ii)
T.
I
.
Avg.
This
mode
is
suitable
for
the
measurement
of
short repetitive
events, with start/stop controls
as
in
T.l.
By
averaging over a
number
of
events the resolution
is
increased.
(iii)
FREQ.
'A'
Provides
frequency
measurement
of the 'A'
channel input with readout
in
kHz.
AUTO
and
MANUAL
Modes
With the
MAN
(manual) switch depressed, the
required
gate time can be selected from the
Range
('n')
buttons.
With
the
AUTO
switch
depressed, the instrument
will
automatically
select the
gate time (.01, 0.1
or
1
second)
which
gives
optimum
resolution
on the display.
(iv)
PERIOD
'A'
Provides period
measurement on
'A'
channel
signal
with readout
in
microseconds.
(v)
RATIO
n-^
Refer
to
para. 2.
9.
(vi)
TOTAL
^
n_
Provides
accumulated
total
of events applied
to
Channel
'A',
with prescaling
by the
factor
'n'
according
to
the
switch selected
in
the
Range
switch
bank.
2-6
9901
Vol.2