7. Set the spectrum analyzer to the following settings:

Center frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..300MH z

Span . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . OHz

Trigger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SINGLE,EXT

a.On the spectrum analyzer, press (SAVE), S.&m STAlZ , STAm 0 .

b.Remove jumper A14J23 and connect a dc voltage source to A14J23 pin 2. Connect the voltage source ground to A14J23 pin 3.

C.Connect a microwave frequency-counter or another spectrum analyzer to the spectrum analyzer first LO OUTPUT (front panel output).

d.Set the dc-voltage source output for 0 Vdc and note the 1st LO frequency.

e.Set the dc-voltage source output for +lO Vdc. The first LO frequency should momentarily increase approximately +15.6 MHz.

f.The voltage at A14U332 pin 2 should be approximately 19% of the voltage at A14J23 pin 2.

g.If the first LO frequency did not change in step e, press ILINE) to turn spectrum analyzer off and disconnect WlO from A14J3.

h.Place a jumper between A14J3 pins 9 and 10. Place a 50 St, 3 watt resistor across A14J3 pins 5 and 6 (resistor, HP part number 0811-1086). Press (LINEI to turn spectrum analyzer on.

i.On the spectrum analyzer, press (E), STAm , STATE 0 .

j. If the voltage at U332 pin 2 is correct with A14J3 pins 9 and 10 shorted, but was

incorrect with WlO connected, the YTO FM coil is probably open; replace the All YTO .

k. Replace jumper A14J23.

Fractional N Span Problems (LO Spans 52 MHz)

If the fractional N spans are inaccurate or non-existent, but the fractional N PLL is locked to the correct frequency and other spans are correct, there may be a problem with the HSCAN signal. Check that HSCAN is present at the fractional divider, U113 pin 41 in function block AS. HSCAN comes from the A3 interface assembly and goes to the sweep generator circuitry in function block A and to fractional N.

Synthesizer Section 1 l-39

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Agilent Technologies 856290216 service manual Fractional N Span Problems LO Spans 52 MHz, Synthesizer l-39