Tektronix 1L30, Инструкция по эксплуатации

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Calibration— Type 1130
Fig. 6-4. Location of sweeper and discriminator adjustments.
i. Adjust the Sweep Center R204 (Fig. 6-4) to position
the 200 M Hz signal at the graticule center line.
2. Adjust Frequency Dispersion and Linearity O
Dispersion accuracy is a measure of the frequency dis­
persion error within 8 centimeters of a 10 centimeter dis­
play. It is measured by positioning a frequency marker
on the 1st graticule line, then noting the frequency error
as the distance the respective marker is displaced from the
9th graticule line. See Fig. 6-5.
Linearity error is the measured distance that any frequency
marker is displaced from its respective graticule line when
compared over an 8 centimeter display. See Fig. 6-6.
Dispersion accuracy and the display linearity for the Type
1L30 is a function of the RF output amplitude, circuit con­
stants, etc. DISP CAL adjustment R208 primarily affects the
dispersion accuracy and C358 (lO M H z /C M Linearity) the
linearity. If these two adjustment will not calibrate the
dispersion to specifications the following techniques may
be tried.
Shift the sweep oscillator RF output voltage to a new
level. (Output voltage level must remain within — 0.7 to
1.0 volt.) If the level is changed, the Center Freq Range
adjustment (step 1) must be repeated.
Interchange Q310, Q340 and G350. The slight differences
between the transistor parameters will have some effect
on display linearity. Interchanging the discriminator cables
(W 375 and W370) with another length is also a possible
correction. Changing these transistors or cables is only
recommended after new transistors have been installed o.r
components have been changed end linearity cannot be
obtained by other means.
a. Equipment setup is shown in Fig. 6-3.
Fig. 6-5. Typical dispersion accuracy displays (step 21.
b. Apply .1 fxs and 10 ns markers from the Time-Mark
Generator (Type 184) through a 20 dB attenuator to the
RF INPUT connector. Set the VERTICAL DISPLAY switch to
LOG position.
NOTE
M o re than one set o f 1 M H z markers m ay a p p e a r
in the d isplay. To avoid confusion, tune the RF
center frequency w ith the RF CENTER FREQ and
FINE FREQ controls to align the tu n a b le markers
with the fixed (IF fee d th ro u g h ) markers.
c. Adjust the G A IN control for a display amplitude of
approximately 3 to 4 centimeters. See Fig. 6-5. Set the
Oscilloscope Source switch to Line and adjust the Level
control for a triggered display.
d. Adjust the DISP CAL R208 for a 1 marker/centimeter
over the center 8 graticule divisions, then adjust C358 (Fig.
6-4) for optimum display linearity.
e. Repeat the adjustment of R208 and C358 until opti­
mum dispersion accuracy and linearity has been achieved.
If the dispersion linearity is not within tolerance, a slight
re-adjustment of R290 and the Center Freq Range R253
adjustments. may be required. .Monitor the voltage at pin
P of the honeycomb square pin connector with the test
oscilloscope to keep the RF voltage amplitude within 0.7
to 1.0 volt.
6-8