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8-15. Output Attenuator Test
This test checks the circuits in the signal path shown in figure 6-7. If the^previous tests have
teen performed, the only major circuits tested are two buffers, and the <WfldB Attenuator.
A d g n a l is derived from-the DAC. It is fed through the Summing Junction, a frequency
s b i i T n e t w o r k . a bufferrthe output attenuator, another buffer and finally, measured at
the VCO CoiSofVoltage Output with an -hp- 3455A voltmeter. The program selects all
four states of the attenuator. checking for the correct voltage readings
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each step. The user is given the option of discontinuing the test after the first reading if the
test appears to be failing. The program prints the results of the test
Initializing the Test
With the High Frequency Menu displayed, press SFK K7 to initialize the test. After in
itialization, follow the instructions displayed on the computer.
What if the Test Fails?
Assuming that the DAC test passed, the only probable causes of failure are: one of tte buf
fers. the frequency shaping network, or the Attenuator. As in the DAC test, SWITCH
T h e usedUo vary the output of the DAC. The signal should then be traced alongthepath
shown in Figure 6-7 using a voltmeter or a scope. Refer to Service Group Three for
schematics, component locators, and circuit descriptions.
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Figure 6-7. Output Attenuator Test
Output Attenuator Test
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