Control Selection; 6.2 Selecting Gate Time - Keithley 775A Instruction Manual

deration
2,6
CONTROL
SELECTiON
Selecting the various
front panel operating
modes
Is
simply
a
mailer
ot
depressing,
once
or twice, the appropriate
but"
ton
as
described
in
the following paragraphs,
2.6.1
Function
The Model
775
must be
set
up
for
the proper
measuring
function with one
of
the four function buttons.
1.
To measure
frequency through the
channel
A
input
ter-
minal,
depre.ss
the
FREQ
button.
2.
To
measure
frequency through
the
channel B input
ter-
minal,
depress the
FREQ
button
a
second
time,
3.
To measure
the period
of
a
signal
through
the
channel
A
input
tenTiina!,
depress
the
PERIOD
button.
4.
lb
nteasure the period averaged of a signal through the
ijiannei
,A
input
terrninai,
depress the
PERIOD
button
a
second
time.
5.
lb measure
time
inten,'als
from events
in
channel
A
to
events
in
channel
B,
depress the
TIME
button,
6.
lb
measure
the pulse
width
of a
pulse
at
channel
.A
in-
put
ternvinal,
depress
the
TIME
button
a
second
time,
Use
the slope button(s)
to select
the desired portion
of
the input
signal.
7.
To
measure frequency through the channel
C
input
ter-
minal',
depress
the
1%EQ
C
button.
2
.
6,2
Selecting
Gate
Time
rr,e
N.'lodei
775
may
be operfhed
in the present gate time
of
one second
or
m
one
of
46 gate times
which
are factorv
selected.
When
selecting the gate time, the
instrument
will
niove
up
or
down
one
gate
time each time
the
^
or
W
button
is
pressed.
The
present gate time
may
be noted on
the display by pressing the
GATE/DELAY
button.
Select the gate time as follows:
1.
Press the
GATE/DELAY
button.
The GATE/DEIAY
light
will
turn
on and
the instrument
will
display the
follow-
ing
message:
GAtE
DDD±D
SEC
2.
To
change
the gate time press the
GATE/DELAY TIME
A
or
T
button
,
Pressing the
A
button
will
increase the
gate time,
Conversely, pressing the
f
button
will
decrease the gate
time.
Holding
in
the
A
or
6u.tton
for
more
than
one
second, causes the instrument
to
in-
crement
or
decrement continuously.
3.
Pressing the
A
and
W
buttons simultaneously
v^'lll
change
the gate
tirns to
a preset value
of Isec,
4.
To
resume normal
display operation, depress
the
GaJE/DELAY
button.
The
GATE/DELAY
light will turn
off
and
instrument
will
be ready
to perforrr!
measurements with
the
newly
selected gate time, Table
2-1 lists the gate/delay times
which
are available.
It is
also possible to
change
the gate
time without
observ-
ing the actual gate
time
on
the display.
To do
so,
simply
press the
GATE/DELAV TIME
4
or
T
button.
Each
time
the
A
button
is
pressed, the
instrument
will
increment
one gate time. Each time the
W
button
is
pressed, the
in-
strument
will
decrement one
gate time.
Holding
in
the
4
or 'f
button
for
more
than one
-Secorid,
causes the
instru-
ment
to
increment
(or
decrement)
after each
measuring
cycle.
Table 2-1.
Gate/Delay Determination
100/4sec
1msec lOmscc 100msec
Isec
lOsec
200fisec
2msec 20msec
200m.sec 2sec User Gate/
300/iSec
3msec 30msec
vTOOmsec 3sec
User Delay
400/isec
4msec
40msec 400msec
4sec
500/iSQC
5msec 150msec 500msec
5sec
fc-OOMsec
6msec
60msec
600msec
6sec
/OCwsec
7msec 70msec 700msec
7sec
fiOOgsec
Smsec 80msec 800msec
Bsec
900iisec
9msec 90msec 900msec
9sec