Operational Checkout; Preliminary Preparation; Operational Check Of Readout Characters - Tektronix 7L5 Instruction Manual

Operating Instructions-7L5 Operators
4. Connect the CALIBRATOR signal to the INPUT
connector on the plug-in module with a short length of
coaxial cable. Adjust the SWP CAL and the HORIZ
POSITION controls to align the second and tenth vertical
signals with the second and tenth vertical graticule lines
counting from the left edge.
5. Set the FREQUENCY SPAN/DIV to 2 kHz, Display
Mode 2 dB/div, and DISPLAY Aand Bon. Adjustthe VERT
POSITION control to place the display baseline on the
bottom horizontal graticule line.
6. Set RESOLUTION control to 3 kHz and DOT FRE-
QUENCY to 500.00 kHz.
7. Select the LOG 10 dB/DIV pushbutton and adjust
the LOG CAL control for a full screen (8 division) display.
8. Select the LOG 2 dB/D IV pushbutton and adjust the
AMPL CAL (on plug-in module) for a full screen display.
9. Repeat steps 7 and 8 until the displayed waveforms
are 8 vertical divisions in both log amplifier settings. (Refer
to Fig. 3-3, Log Amplifier Calibration Composite
Waveform.) If desired, check linearity of the 10 dB/div
display by increasing the REFERENCE LEVEL in 10 dB
steps. Adjust LOG CAL slightly to correct any non-
linearity.
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Fig. 3-3. Log amplifier calibration composite waveform.
3-8
OPERATIONAL CHECKOUT
Introduction
This is an operational checkout procedure intended to
satisfy most customer's recelvmg inspection re-
quirements and to provide instrument familiarization for
the new user. We recommend using this checkout as part
of the users routine maintenance program and a
preliminary check before performing the Performance
Check portion of the Service Instruction manual.
The front panel CALIBRATOR output is an accurate
signal source and is used in the following procedures to
verify operational status of the instrument. Calibnitor
frequency accuracy may be verified by applying it to an
accurate digital counter.
Some procedures require a step attenuator and two
short lengths of coaxial cable. To verify the absolute
reference level specifications, the attenuator accuracy
must be calibrated or verified at some specific frequency,
to within 0.03 dB/dB with a cumulative error not to exceed
0.1 dB for any change up to 10 dB. Incremental accuracy
can be verified and a good indication of the absolute
reference level accuracy can be obtained by using two
Tektronix Step Attenuators, such as the 2701 (see Op-
tional Accessories, Section 1). These attenuators provide
a good indication of operation even though their accuracy
specifications are not within the limits described.
1_ Preliminary Preparation
Preset the front panel controls and selectors as
described under Calibrating the 7L5 to the Oscilloscope
Mainframe and perform the calibration procedure as
previously described.
2_ Operational Check of Readout Characters
With the 7L5 installed and operating in a 7000-Series
mainframe, perform the following steps to check the
readout operation.
Dot Frequency Readout
a. Verify that the dot frequency readout is 0.00 kHz
after initial tu rn-on. (Readout characters for the dot
frequency are located near the top edge of the crt and can
be identified by the suffix characters kHz) .
b. With the FINE TUNING pushbutton not illuminated
(inactive), verify that the DOT FREQUENCY control
changes the value of the readout characters in 10kHz
increments.
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