Tektronix 1L10, Instruction Manual

Page: 21 / 72

Maintenance and Calibration— Type 1 LI 0
Fig. 4 -6 . Equipment setup for Dispersion Check/adjustment at .01 , .02 , .05 K C /C M settings of DISPERSION-KC/CM switch.
{6 0 me) o f the 5-m c signal from the Type 180A .
This signal w ill n o rm a lly a p p e a r to the rig h t o f
th e g ra tic u le centerline.
16. Reduce the output amplitude of the audio generator
so that it is not modulating the Type 180A signal.
17. Set the output frequency of the Type 105 Square-
W ave Generator to about 3 kc and adjust its output am pli­
tude so that the modulation markers are clearly visible.
18. Set the output frequency o f the Type 105 Square-
W ave Generator so that the first modulation marker on the
left-hand side of the center frequency is at the graticule
centerline (see Fig. 4-7).
19. Set the DISPERSION-KC/CM and COUPLED RESOLU­
TION switches to 1, .5, .2, .1 and .05 while keeping the
Type 105 Square-Wave Generator signal positioned to the
graticule centerline by varying the output frequency.
20. Set the sweep rate of the oscilloscope to .2 SEC.
21. Set the output frequency of the audio generator to
50 cps and increase the output amplitude of the audio gen­
erator until the 50 cps modulation is clearly visible. Check
for 1 marker/cm, + 1 3 % , —7%.
22. Using Table 4-2, check the .2 and .1 settings of the
DISPERSION-KC/CM switch. The markers should be 1 cm
apart + 1 3 % , —7% at all settings. If not, calibrate the dis­
persion of the instrument per the Calibration Procedure in
this section. In each case, set the COUPLED RESOLUTION
switch to the same setting as the DISPERSION-KC/CM switch.
Keep the display centered by slight adjustment of the Type
105 Square-Wave Generator frequency.
Fig. 4 -7 . Initial display (step 18 ) in checking the narrow disper­
sion settings of the Type 1L10.
TABLE 4-2
DISPERSION-KC/CM A u d io
COUPLED
G e n e ra to r
O scilloscope
RESOLUTION Setting Frequency
Sweep Rate
.02
20 cps .5 SEC
.01 10 cps
1 SEC
4 -5