Tektronix DC 501 Instruction Manual page 7

Operating Instructions—
DC
501
Fig
1-2.
Two
examples of triggering circuit
output showing
how
proper adjustment of
TRIGGERING LEVEL
control
can avoid an
erroneous count.
The
DISPLAY TIME
control sets
the length
of time
a
measurement can be held
in
the
counter and displayed.
The
HOLD
detent
position allows
a
measurement
to
be
held
indefinitely,
or until
the counter
is
reset
to zero
by the
front-panel
RESET
button.
Count;
Register capacity,
10';
totalizes
events
accumu-
lated
between
start/stop
commands from
front-panel
button.
INPUT
Frequency,
10
Hz
to
100
MHz;
sensitivity,
300
mV
peak
to peak; triggering level,
adjustable
+2V;
attenuator,
XI,
X5, XIO,
or
X50;
maximum
input voltage,
500
V
(DC
-i-
peak
AC,
or
peak
to
peak
AC)
at
1
kHz
or
less;
impedance,
(EXT
input),
approx
1
MO
paralleled
by about
20 pF
(INT
input)
approx 5012
paralleled
by about 20 pF;
coupling,
AC.
INTERNAL TIME BASE
Standard
Option
1
Crystal
Frequency
1
MHz
5
MHz
Stability
(0°C
to
-i-50°C), after 1/2
hour
warm-up
Within
1
part
in
10®
Within
5
parts
in
10'.
Long-term Drift
1
part or less in
10^
per
month
1
part or
less in
10'
per
month
Accuracy
Adjustable to
within
1
part
in
10'
Adjustable
to
within
5
parts
in
109.
INTERNAL
MEASUREMENT
INTERVAL.
Selectable
in
decade
steps.
Optional Features
Option
1-0.5
P/M
5
MHz
Crystal Oscillator.
The
DC
501 can
be ordered
with
a
temperature-compensated
crystal
oscillator to
provide
a
highly stable
and
precise
internal
time
base
TMHz
clock.
This option includes
a
divide-by-five
1C counter
to provide the
proper output.
Option
2-Automatic Gate Control and
Readout Scaling
Circuit.
This circuit
automatically
selects
the 0.1
-,
1-,
or
10-second
measurement
interval to
display the largest
number
of digits
without overflow,
and provides the
appropriate scaling of decimal-point
and
units lights to
produce the correct display.
If
overflow
indication occurs,
the input signal
is
>
100
MHz
and
the
overflow
digit
is
a
"
1
".
Measurement
Interval
Display
Units
Resolution
10
ms
000.0000
MHz
100
Hz
100
ms 00.00000
MHz
10
Hz
1
s
0000.000
kHz
1
Hz
10s 000.0000
kHz
0.1
Hz
Manual
0000000 (adds to displayed
number)
Accuracy, within ±
;
± time-base accuracy.
total
count
DATA PRESENTATION
Visual
numerical readout, seven 7-segment
LED
with
automatically positioned decimal
point; units,
LED
indi-
cates
kHz
or
MHz;
overflow,
LED
indicates that
readout
is
exceeded; gate,
LED
indicates
open
gate.
Electrical
Characteristics
MEASUREMENT RANGES
AND ACCURACY
Frequency:
10
Hz
to
100
MHz;
0.1-s to 10-s
counting
gate time; displays
kHz
or
MHz
units
with positioned
decimal point.
Accuracy, ±1 count
± time-base accuracy.
DATA
INPUTS
and
OUTPUTS
Available
via
plug-in
connector to
50-pin connector
at
rear of
Power Module. Input
lines
are available for signal
input,
and
internal
and
external scan clock control.
Output
lines
are available for
BCD
output
(serial-by-digit),
and
to
indicate status of timing, data
good,
reset, scale,
decimal
point
and
overflow.
1-3