Settings Of Sweep Switches; Yto Fm Coil Span Problems (Lo Spans 1.01 Mhz To 20 Mhz - HP 8560A Service Manual

YTO FM Coil Span Problems (LO Spans 1.01 MHz to 20 MHz)

In YTO FM Coil spans, the YTO loop is locked and then opened while the sweep ramp is
summed into the FM coil. FM spans are adjusted by changing the sensitivity of the FM coil
driver.
1. Perform the YTO Adjustment procedure in Chapter 2. If the YTO adjustments cannot be
performed, continue with this procedure.
2. Set the HP 8560A to the following settings:
C E N T E R F R E Q . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SPAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SWEEPTIME . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3. Check for the presence of a 0 V to -10 V sweep ramp at A14J15 pin 14 (input to the
Schematic (sheet 2 of 5).
4. Check for the presence of a 0 V to +5 V sweep ramp at A14U405 pin 6 (YTO FM Coil
Driver). Refer to function block N of Al4 Frequency Control Schematic (sheet 2 of 5).
5. Check the state of the Main/FM/VCO S weep Switches as indicated in Table 10-8.
6. The rest of the procedure troubleshoots the YTO FM Coil Driver. Refer to function block
N of Al4 Frequency Control Schematic (sheet 2 of 5).
Switch
7. Set the HP 8560A to the following settings:
C E N T E R F R E Q
SPAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TRIG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8.
On the HP 8560A press
9. Remove jumper A14J23 and connect a dc voltage source to A14J23 pin 2.
10. Connect a microwave frequency-counter or spectrum analyzer to the HP 8560A's 1ST LO
OUTPUT.
11. Set the dc-voltage source's output for 0 Vdc and note the 1st LO frequency.
12. Set the dc-voltage source's output for +lO Vdc. The 1st LO frequency should increase
approximately +15.6 MHz.
Table 10-8. Settings of Sweep Switches
Switch State
Open
Open
Closed
Closed
Closed
Open
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Switch Control Line
1
9
16
1
8
Synthesizer Section lo-17
.. 300 MHz
..20 MHz
5 0 m s
Control Line State
High
High
Low
High
High
Low
.. 300 MHz
.. SINGLE