Tektronix 442, Инструкция по эксплуатации

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Operating Instructions—442 Service
6. Measure the vertical deflection in divisions, and
calculate the amplitude of the unknown signal using the
following formula:
VOLTS/DIV vertical vertical
Signal _ switch X conversion X deflection
Amplitude setting factor (divisions)
5. To measure the period of a signal, disconnect the
reference signal and connect the questioned signal to the
selected channel input connector. SettheSEC/DIVswitch
to a setting that provides a sufficient horizontal display to
make an accurate measurement (at least one full cycle).
Do not readjust the VAR control.
EXAMPLE: Assume a reference signal amplitude of
30 V, a VOLTS/DIV switch setting of 5, and the VAR
control is adjusted to provide a vertical deflection of 4
divisions.
Substituting these values in the vertical conversion
factor formula (step 4):
Vertical 3Q y
Conversion = ~4~x~sV = 15
Factor
Then with a VOLTS/DIV switch setting of 1, the peak-
to-peak amplitudeof an unknown signal which producesa
vertical deflection of 5 divisions can be determined by
using the signal amplitude formula (step 6):
Signal = 1 V X 1.5 X 5 = 7.5 volts
Amplitude
Sweep Rates. To establish an arbitrary horizontal
sweep rate based upon a specific reference frequency,
proceed as follows:
1. Set the VERT MODE switches to display the
selected channel and connect a reference signal to the
selected channel input connector. Set the VOLTS/DIV
switch for 4 or 5 divisions of vertical deflection.
6. Measure one full cycle of the horizontal display in
divisions and calculate the period of the unknown signal
using the following formula:
SEC/DIV horizontal horizontal
Period = switch X conversion X display
setting factor (divisions)
EXAMPLE: Assume a reference signal frequency of
455 Hz (period 2.19 milliseconds), and a SEC/DIV switch
setting of .2 m, with the VAR control adjusted to provide a
horizontal deflection of eight divisions. Substitutingthese
values in the horizontal conversion fact or formula (step 4):
Horizontal
Conversion =
Factor
2.19 milliseconds
. 2X8
1.37
Then, with a SEC/DIV switch setting of 50 fj the
unknown period of a signal, which completes one cyclein
7 horizontal divisions, can be determined by using the
period formula (step 6):
Period = 50 /us X 1.37 X 7 = 480 //s
This answer can be converted to frequency (repetition
rate) by calculating the reciprocal of the period.
2. Set the SEC/DIV switch and VAR control so one
cycle of signal covers an exact number of horizontal
divisions. Do not change the VAR control setting after
obtaining the desired deflection. This display can be used
as a reference for frequency comparison measurements.
Time-Duration measurements
To measure time between two points on a waveform,
use the following procedure:
1. Connect a signal to either the Channel 1 or the
Channel 2 input connector.
3. Toestablish an arbitrary sweep rate sothe unknown
period of a signal can be measured accurately at any
setting of the SEC/DIV switch, the period of the reference
signal must be known. If it is not known, it can be
measured before the VAR control is set in step 2.
2. Set the VERT MODE switches to display the
selected channel.
3. Set the VOLTS/DIV switch to display about 5
divisions of waveform.
4. Divide the period of the reference signal (seconds)
by the product of the horizontal deflection established in
step 2 (divisions) and the setting of the SEC/DIV switch.
This is the horizontal conversion factor:
Horizontal
Conversion =
Factor
reference signal period (seconds)
horizontal deflection (divisions)
X SEC/DIV switch setting
4. Set the Triggering controls to obtain a stable
display.
5. For best accuracy use a SEC/DIV setting that gives
the greatest number of on-screen divisions between time
REV A MAY 1980
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