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NOTE: The input
circuit
oI the
5228
is direct
coupled
-
to the amplitude
discriminator.
Any dc
volt-
age
present at the input
will
a{Iect the
sensitivity
oI
the
amplitude
discriminator circuit
when rlreasuring
FREQUENCY
or PERIOD.
U dc
voltage
is
present,
an
erternal 2pI blockirg capacitor
connected
in
series
with the
INPI-IT
jack
wi}l.
allow measurements to
be
made down
to
I
cps
at rated
sensitivity.
A larger
capacitor
is
required
for
lower frequencies,
Frequency Measurement
a.
Set
the
FUNCTION SELECTOR
switch
to FRE-
QUENCY
and
the
FREQUENCY
UNrI
slvitch to
the
STD.
GATE
TIME position that provides
the
de-
sired measuring unlt. MANUAL GATE switch in
t}te
closed position.
b.
Connect
the
unknown
irequency to the hiPUT
connector of the
instrument.
The input voltage
must not exceed
100
volts.
As
this instrument
is
iilgg-ded
wEen
ev
erlft-ilput
voltage passes through
zero,
any
direct current
coinponent
in
tle
input
volt-
age
will
change
the
triggering
point.
For example, ar
input voltage
of
5
volts which
has
a
direct currerlt
component
of
10
volts
will
not
trigger
the
instrument, However, an input voltage
oI
15
volts
with
a
10
volt direct current
component
wiIl trigger
t}Ie
instrument at the
10
volt
level.
c.
The
MANUAL
GATE
switch
mal, be
used
to
extend
the
time that the gate is
open so
that multiples oI
the selected gate
time
mal, be
obtained.
/y'hen
the
MANUAL
GATE
srxitch
is
in the
OPEN
position ttle
gate
camot close.
When
the
switch
is
returned to
Ure
closed
position,
t}le
gate
wiU close at the next
timing
pulse.
To
extend
tie
gate
time,
the
MANUAL GATE switch
is
placed
in
the OPEN
position.
Just
prior
to
the
desired count time the MANUAL CATE switch should
be returned
to
normal,
and
the next
timing
pulse
will
accurately close
tie
gate.
Example:
It
is desired to
measure
a
5000
cycle/sec.
wave
for
a
time oi
4
aecords. The
time unit selected
on
the
FRE-
QITENCY
UNTI
switch vDuld be
1
secord.
The
MAN-
UAI
GATE
switch
may be open
eitler
before
or after
the
count has begun
but must
be open
before
1
second
oI counting
time
has eLapsed.
It
must be closed be-
tween
the
3rd
and
4th second
of
counting
time.
d.
Adjust the DISPLAY TIME control
so
that
the
count
is
displayed long
enough
to
be read con-
veniently. The
count
display
wiu
be
cycles
or kilo-
cycles
per
second as
indicated by the position of the
FREQUENCY
UNIT switch.
Sect.
II
Page
3
10
Period Average Measurement
a.
Set
the
FUNCTION SELECTOR
switch
to the
10
PERIOD
AVERAGE
position
and
the
TIME
UNIT
switch
for
the
desired unit
time.
Connect the wave-
Iorm to
be measured
to the INPUT terminal.
The
direct current
component
of
the input waveform must
be
considered as
it will
produce
t-he
elfects described
in the
Frequency
Measurement
procedure. The MAN-
UAL GATE switch should
be
in the closed position.
b.
Adjust
the
DEPLAY TIME control
for
convenient
reading of the
count. The displayed count
will
be
the average period of
one
cycle although
10
cycles
were measured.
The MANUAL GATE
switch
will
function on period
meassrements
similar to
Irequency measurement,
However,
on
period measurenents the time is
a
multipLe
of the input wave,
Ior
example:
It is
desired to measure the period of a
20
cycles,/
sec.
wave
for
100
periods.On
10
period average the
count
displayed
wiU be 50.0
milliseconds.
Then
for
100
periods which
is
10
times
10
period average, the
count should be
500.0
n)illiseconds.
Thus
the MAN-
UAL GATE switch should be closed
between
the
gt}l
and
10th
ten
periods which
would be between
450.0
and 500.0
count. The period of the
20
cycles,/sec.
wave
will
now
be 500.0
divided
by
10
or
50.00
milli-
seconds. The accuracy has
been
increased
by
ten
times over the
accuracy
oi the ten period
average.
Period
Measurement
fire
pToc.eaure
ior
nreasuring
the
period of
one
cycle
is the same
as
for
the
10
Period Average except that
the FUNCTiON SELECTOR
switch
is
set
at
PERIOD.
Time Interval Measurement
t--5eatha-FlNa-IoFsmEcroR
switch at
rIME
INTERVAL
and
the TIME UNIT switch at the
desired
time unit.
The MANUAL
GATE
control
must
be
in the closed position.
b.
If
the
internl
of
time to be measured
is
a
pulse-
width, repetition rate, rise time oI
a sloping
wave,
or
some
other function in which
both
start
and
stop lnformation
is
on a
single
wire,
set
tJle
SEP.
-COM. switch to COM.
and connect
t]Ie
input
voltage
to
eitler
the START or
STOP
terminai.
In
t}le
COM. posiiion the two inputs are tied togetler.
II
the
interval to
be
measured
is from
two separate
sources
-
such as
two phototubes
or
two sine
waves
of di-flerent phase
-
place
the
SEP.
-COM. switch in
SEP. Connect the
starting signal to tlle
START
ter-
minal
and
the stop signal
to the
STOP
term
inal
c.
The TRIGGER SLOPE
switches
and TRIGGER
LEVEL VOLTS controls are the
same
for
bot}l
the
start
and
stop
channels. The loUowing consider-
ations
therelore apply to
both channels.
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