Tektronix DC 502 User Manual

Operating Instructions — DC 502
OPERATIONAL CHECK
Display Check
Press the RESET button to check the 7 character
segments of each digit; the numerical display should be a
row of eights. To check the decimal point position and the
units indicators, set the MEASUREMENT INTERVAL
switch as follows:
Switch
Position
.01 SEC I
.1 SEC 1
_ ( DIRECT
1 SEC / .
I INPUT
10 SEC I
MANUAL /
MANUAL 1
1 M0
10 SEC I
. I PRE-
1 SEC >
.1 SEC SCALE
1 INPUT
.01 SEC 1
Numerical
Display
Units
.0000
MHz
.00000
MHz
.000
kHz ’
.0000
kHz
000
000
.000
kHz
.00000
MHz
.0000
MHz
.000
MHz
In the MANUAL position, no decimal point will be
displayed. Press the START button and check that the
GATE indicator lights, then release the button (STOP) and
check that the GATE light goes out. To check the
OVERFLOW indicator, set the MEASUREMENT
INTERVAL switch to 10 s and apply 15- or 20-MHz to the
INPUT connector. The length of time a display can be held
is determined by the DISPLAY TIME control, and will be
discussed in the next few paragraphs.
Then turn the MEASUREMENT INTERVAL switch to the
position that gives the desired reading. Generally, use the
shorter measurement intervals for high-frequency, low-
resolution measurements and the longer intervals for
measurements requiring a high resolution.
NOTE
The OVERFLOW indicator can be lit for high-
resolution measurements, allowing the frequency to
be indicated to 0.1 Hz. Refer to the Specifications at
the end of this section for resolution and accuracy at
each position of the MEASUREMENT INTERVAL
switch.
The display is updated at a rate determined by the
DISPLAY TIME control. Each time a sample of the input
signal is taken, the GATE light will flash and the new
reading will be displayed. To change the display time,
which is continuously variable from about 0.1 second to 10
seconds, or to hold a display indefinitely, turn the
DISPLAY TIME control.
÷10 Pre-Scale Input. The DC 502 also provides a pre 
scaled, AC-coupled input to measure the average frequency
of signals from 50 MHz to 550 MHz. This input has a
sensitivity of 500 mV, peak-to-peak, and a maximum input
voltage limit of 10 V, peak-to-peak. Signals greater than
10 V may damage the diodes of the input circuit. The
ATTEN controls do not apply to this input.
Frequency Measurements
Direct Input. The DC 502 provides direct measurement
of the average frequency of signals from about 10 Hz to
110 MHz. The input sensitivity is 300 mV peak-to-peak, so
select the proper attenuation (X 1 , X5, X10, or X50) for the
given signal.
The input signa! must not exceed 500 volts.
Apply a 50 MHz to 550 MHz signal of at least 500 mV
amplitude to the ÷10 PRE-SCALE INPUT. Set the
MEASUREMENT INTERVAL switch to .01 SEC and
observe the readout. Leading zeros should be blanked.
Select a MEASUREMENT INTERVAL which gives the best
accuracy and resolution. As with the DIRECT INPUT,
shorter measurement intervals give higher frequency, lower
resolution measurements; longer intervals offer greater
resolution, especially when overflow is employed.
Apply a signal to the INPUT connector. Set the
MEASUREMENT INTERVAL switch to the .01 SEC posi 
tion and the DISPLAY TIME control fully CCW. Observe
the numerical readout display. Adjust the TRIGGER
LEVEL control for a stable reading. The zeroes leading the
most significant digit in the display should be blanked.
Totalizing
DIRECT INPUT. The DC 502 will count and display the
accumulated number of signals (events) applied to the
DIRECT INPUT connector up to the register capacity of
9,999,999 during the time interval between START/STOP
commands from the front-panel pushbutton. Input signal
rate should not exceed 110 MHz.
®ï 1-2
REV. MAY 1974

Tektronix DC 502 Specifications

General

Brand	Tektronix
Model	DC 502
Category	Cash Counter
Language	English