Tektronix 1L10, Instruction Manual

Page: 19 / 72

Maintenance and Calibration— Type 1 LI 0
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RF INPUT
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Calibrated
Amplitude
R.F. Source
10 me
Fig. 4 -2 . Equipment setup for making sensitivity check.
Fig. 4 -3 . Measurement of relative amplitude between an applied
low-level signal and the noise of the system, (a ) Amplitude of
signal and (b) amplitude of noise.
the displayed noise. If the amplitude of the display is not
at least two times noise, set the DISPERSION-KC/CM and
COUPLED RESOLUTION switches to .01, and set the VER­
TICAL DISPLAY switch to LIN X 10. Slow the sweep rate
of the oscilloscope to .5SEC/CM. If the signal amplitude is
still not two times as great as noise, the instrument needs
a complete calibration.
Dispersion Check
1. Connect the equipment as shown in Fig. 4-4.
2. Set the front-panel controls on the Type 1 LI 0 as fo l­
lows:
RF CENTER FREQ 10
VERTICAL POSITION Midrange
R-F ATTEN All OFF
VERTICAL DISPLAY LIN
G AIN Midrange
DISPERSION-KC/CM
2
COUPLED RESOLUTION
2
INT OSC EXT OSC INT OSC
4. Set the Type 180A Time-Mark Generator for an output
frequency o f 5 me.
5. Using the RF CENTER FREQ control o f the Type 1L10,
tune the 2nd harmonic (10 me) of the Type 180A signal to
the center of the screen.
6. Set the G A IN control and R-F ATTEN switches o f the
Type 1 LI0 for about 6 cm o f the displayed signal.
7. Set the output frequency of the audio generator to
2 kc.
8. Set the output amplitude o f the audio generator and
the controls on the Harmonic Modulator Unit for maximum
modulation (maximum number of side-frequency markers).
See Fig. 4-5 for the desired display.
4 -3