Chapter 11 573
Synthesizer Section
Frequency Span Accuracy Problems
10.Set the spectrum analyzer to the following settings:
Start frequency ............................................................. 10MHz
Stop frequency ..............................................................2.9GHz
Sweep time ....................................................................... 80ms
11.Monitor A14J15 pin 14 for a 0 V to −7.4 V ramp. Switches U317A,
U317B, and U317D should be open and U317C should be closed.
12.Change the spectrum analyzer SPAN to 365 MHz and check for a
0to−936 mV ramp at A14J15 pin 14. Switches U317A, B, and C
should be open and U317D closed.
13.Change the spectrum analyzer SPAN to 36.5 MHz and check for a
0to−93.6 mV ramp at A14J15 pin 14. Switches U317B, C, and D
should be open and U317A closed.
1st LO Span Problems (Multiband Sweeps)
During multiband sweeps, the sweep ramp at A14J15 pin 15 should go
from 0 V to +10 V for each band or portions of a band covered. See
function block A of A14 frequency control schematic (sheet 1 of 5) in the
8560 E-Series Spectrum Analyzer Component Level Information. However,
the scan ramp at A14U325A pin 1 is scaled according to the percentage
of the total span that the band is covering. See function block B of A14
schematic (sheet 1 of 5). Also, the sum of the individual ramps is 10 V.
For the 8564EC,Figure 11-9 on page 574 illustrates both sweep and
the scan ramp for a 0 GHz to 40 GHz span with instrument preset
conditions. For the 8565EC,Figure 11-10 on page 574 illustrates
both sweep and the scan ramp for a 0 GHz to 50 GHz span with
instrument preset conditions.
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