3.Check maximum power available from the TG. Connect the RF OUT 50R to the INPUT 50R. Press (??%??I, IAMPLITUDE), 0, @, (z), LOG dB/DIV ,a, (dB), (mj, TRACKING GENRATOR , SRC PWR ON , MORE 1 OF 3 , ALC EXT. No connection should be made to the ALC EXT INPUT connector on the rear panel. The available power should always be greater than +l dBm. If the output is unleveled only at specific frequencies, a power hole will usually be visible at those frequencies.

4.Perform the 1ST LO OUTPUT Amplitude performance test. If the test fails, note the Center Frequency setting at which the power level was out-of-tolerance. Repeat the test with the power sensor connected to A7J3 (a right-angle SMA adapter will be necessary) and note the Center Frequency of any out-of-tolerance power levels. The power level should be +16.5 dBm f2 dB.

If the power level is correct at W43 but out-of-tolerance at the 1ST LO OUTPUT (front panel) and the Center Frequency setting of the out-of-tolerance power levels is close to the frequencies at which the output is unleveled, suspect either A10 or W46.

If the power level at W43 is also out-of-tolerance, suspect either the A7 LODA or the All YTO. Refer to Synthesizer Section Troubleshooting.

5.If the output is unleveled only at certain power level settings or certain frequencies, monitor A17J16 pin 1 with a DVM. Connect the negative DVM lead to A17J16 pin 6. Vary the TRK GEN RF POWER or Center Frequency settings, as appropriate, and plot the voltage variation versus power level or frequency. A discontinuity in the plot near the frequency or power level at which the output is unleveled indicates a problem on the Al4 Frequency Control Assembly.

Excessive Residual FM

Either the tracking oscillator or the ALC circuitry could be responsible for excessive residual FM. The residual FM should be measured on another spectrum analyzer, such as an HP 8566A/B or HP 8568A/B, using slope detection with the HP 8560A set to zero span.

Proceed as follows to troubleshoot residual FM problems:

1.Perform the Residual FM performance test for the spectrum analyzer in the Installation and Verification Manual. If this test passes, the 1st LO input and 600 MHz drive signals should be correct. If the test fails, troubleshoot the Synthesizer Section.

2.Monitor A14J17 pin 15 (TUNE +) with an oscilloscope. Connect the oscilloscope probe ground lead to A14J17 pin 6. The voltage at this point should be greater than 500 mV. If the voltage is less than 500 mV, perform the Tracking Oscillator Range performance test in the Installation and Verification Manual. If this test fails, perform the Tracking Oscillator Range Adjustment. If the noise on this tune line is greater than 10 mV, troubleshoot the BITG Drive circuitry on A14.

3.Monitor the output of the tracking generator with another spectrum analyzer. Check for high-amplitude spurious responses from 100 kHz to at least 3 GHz. If the spurious responses are too high in amplitude, the (broadband) ALC detector may cause the ALC loop to oscillate, generating FM sidebands.. If any spurious responses are excessively high, refer to Harmonic/Spurious Outputs Too High below.

4.If no spurious responses are present or are sufficiently low enough in amplitude to not cause a problem, suspect the tracking oscillator in AlO.

11-20 RF Section