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13. The voltage at A14U332 pin 2 should be approximately 19% of the voltage at A14523
pin 2.
14. If the 1st LO frequency did not change in step 12, set the HP 8560A's (LINE) switch OFF
and disconnect WlO from A14J3.
15. Place a jumper between A14J3 pins 9 and 10 and set the (LINE) switch ON.
On the HP 8560A press
17. Repeat steps 6 through 13.
18. 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.
19. Replace jumper A14J23.
Roller Oscillator Span Problems (LO Spans 51 MHz)
The following procedure troubleshoots problems with the Roller Oscillator PLL's Main
Oscillator (101 kHz to 1 MHz) and Offset Oscillator (5 100 kHz).
1. Set the HP 8560A to the following settings:
C E N T E R F R E Q
SPAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..lMHz
RES BW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10kHz
VIDEO BW
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10kHz
SWEEPTIME . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50ms
2. Set an oscilloscope to the settings listed below and monitor A14J17 pin 1. The waveform
should look similar to Figure 10-6.
Amplitude Scale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250 mV/div
Sweep Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..50ms/div
Graph
X S e l e c t e d
4 8 4 mV
0 . 0 0
C u r s o r 0
4 8 4 mv
0 . 0 0
C u r s o r o - x
0
00
0
00
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...300 MHz
1
1
2 5 0 mV/div
0 . 0 0 v
1 :
v
Figure 10-8. Input to YTO FM Coil Driver
5 0 . 0 0 ms/div
0
000
S K 1 1 0 6
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