Tektronix 1L30 Instruction Manual page 54

j
Performance Check— Type 1L30
d. Adjust the G A IN control for a signal amplitude of
4 cm on the plug-in oscilloscope screen.
e. Check the accuracy of the IF ATTEN dB selectors as
follows:
1. Switch the Type 1130
I
O N and switch out 1 dB of attenuation through the units
j
Step Attenuator.
2. Check the display
± 0 . 5 mm (.1 dB/dB).
j
i
3. Switch the Type 1L30 IF ATTEN switch to OFF posi­
tion, then check the remaining IF ATTEN switch steps
as directed in Table 5-3a.
■ I
TABLE 5 -3 a
•i
3
Spectrum A nalyzer
i
Attenuators
IF ATTEN Switch
1
Units
On
3
■ 5
1 dB 11
I
10
2 dB
4 dB
. 8 dB
16 dB
20 dB
The 1 and 2 dB measurements are very difficult, because
of signal stability and the noise level. For these small sig­
• s
■ 1
nal levels, the square law mode may be used to expand the
screen changes for the same level change by the square
power as listed in Table 5-3b.
|
1
dB
Signal 3.95
Amplitude to
limits 4.05
An alternate method which is not as accurate but is suf­
ficient for most applications is as follows:
1. Apply a 200 MHz signal (at 60 dB below 1 mW, as
shown on the Attenuator dial) from the Signal Generator to
the R.r INPUT connector. Adjust the Spectrum Analyzer G A IN
control for a signal amplitude of 5 cm.
5 6
- -
Fig. 5-5. Equipment setup to check attenuator accuracy.
1 dB attenuator switch to
amplitude. Must equal
Step
Signal Am plitude
Tens Limits (.1 d B /d B )
20 3.95 cm to 4.05 cm
20 3.9 cm to 4.1 cm
3.8 cm to 4.2 cm
8 20
3.6 cm to 4.4 cm
4 . 20
10 3.2 cm to 4.8 cm
6
2.95 cm to 5.05 cm
2 10
TABLE 5 -3 b
2 8 16
4
3.9 3.6 3.2 2.2
to to
to to
4.1 4.4 4.8 5.8
2. Switch the 1 dB IF ATTEN switch on and adjust the
Signal Generator output attenuator control to return the
signal amplitude to 5 cm.
3. Check the new reading of the attenuator dial. Should
read — 59 dBm ± 0 .1 dBm.
4. Turn the 1 dB IF ATTEN switch to OFF. Check the re­
mainder of the IF ATTEN selector steps as directed in
Table 5-3c.
4 cm,
Spectrum A n a ly ze r
IF ATTEN switch on
2 dB
4dB
8 dB
16 dB
20 dB
9. Check Attenuation Range of G AIN Control
a. Requirement— The attenuation range of the G A IN con­
trol should equal or exceed 50 dB.
b. W ith the 200 M Hz IF feedthrough signal applied as
directed in step 7 and the G A IN control turned fully counter­
clockwise, adjust the Signal Generator Variable Attenuator
control for a signal amplitude of 6 cm. Note the Attenuator
reading in dBm.
c. Increase the Signal Generator output attenuation by
50 dB. Turn the G A IN control fully clockwise.
d. Check— Signal amplitude must equal or exceed 6 cm.
(Range > 5 0 dB.) If the range does not meet this requirement,
recheck the adjustment of the Narrow Band IF, as described
20
in the Calibration section.
1.7
to
6.3
10. Check Signal Amplitude at TO RECORDER
Connector
a. Requirement— Signal amplitude at the TO RECORDER
output connector with a full screen display (6 cm) should
measure -between
terminated into a 600 ohm load.
b. Set the front panel controls as follows:
TABLE 5 -3 c
RF G en erato r Attenuatjor
Control Setting
— 58 dBm ± . 2 dBm
— 56 dBm ± . 4 dBm
— 52 dBm ± . 8 dBm
— 44 dBm ± 1 . 6 dBm
— 40 dBm ± 2 .0 dBm
12 mV and 20 mV when the output is
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