Flatness
The output level flatness of the tracking generator is specified at a 0 dBm output power setting. In general, most flatness problems will be a result of a failure in the A10 Tracking Generator microcircuit. However the POWER LVL signal from the Al4 Frequency Control Assembly and the 1ST LO IN signal from the A7 LODA can also contribute to flatness problems.
1.Check the function of the POWER LVL signal from the Al4 Frequency Control Assembly. Set the TRK GEN RF POWER to a level at which the flatness is
2.Check the flatness of the 1ST LO IN signal. Perform the 1ST LO OUTPUT Amplitude performance test. If the test passes, the fault is most likely in the A10 Tracking Generator. If the test fails, note the Center Frequency setting at which the power level was
If the power level is correct at W43 but
If the power level at W43 is also
3.Check all coax cables, especially
Vernier Accuracy
Vernier accuracy is a function of the POWER LVL drive signal from the Al4 Frequency Control Assembly and the ALC circuitry on AlO. The vernier accuracy is specified at
300 MHz. Since vernier accuracy is tested using a broadband power sensor, abnormally high spurious responses could cause the measured vernier accuracy to fail when in fact the accuracy of the 300 MHz signal alone is within specification.
1.Check the POWER LVL drive signal from A14. Monitor A17J16 pin 1 with a DVM. Change the TRK GEN RF POWER in 1 dB steps and note the voltage at each power level setting. The voltage should change by the same amount for each 1 dB step. If the voltage does not change by the same amount for each 1 dB step, the fault lies on the Al4 Frequency Control Assembly.
2.Check for abnormally high spurious outputs. Connect the RF OUT 5OQ to the input of another spectrum analyzer (the “test analyzer”). Set the test analyzer to sweep from
300 kHz to 2.9 GHz, with a sweeptime of 100 msec or less. Set the HP 8560A to sweep from 300 kHz to 2.9 GHz with a 50 second sweeptime. Press (SGLSWP) on the HP 8560A and observe any responses on the test analyzer, ignoring the desired output signal. If any spurious responses are greater than
RF Section