122 E8257D/67D, E8663D PSG Signal Generators Service Guide
Troubleshooting
Troubleshooting the RF Path
Troubleshooting the RF Path
Troubleshooting RF Path procedure:
— preset the signal generator
— set a frequency
— open ALC loop (ALC Off)
— set signal generator to maximum power
— check power levels in the RF path using “Troubleshooting RF Power
Levels”, below.
Troubleshooting RF Power Levels
The following information has been provided to aid in troubleshooting power
levels in the RF path:
—RF Block Diagrams (see Figure 1-9 on page 167 and Figure 1-10 on
page 169 for the E8257D, and Figure 1-13 on page 175 and Figure 1-14 on
page 177 for the E8267D). The block diagrams show signal flow, path
frequency ranges, and minimum power levels ts a few key points in the RF
path.
— A Gain/Loss table (Table 1-28 on page 165). The table provides the
minimum gain or maximum loss level between the input and output for
each part
When troubleshooting the instrument, the troubleshooting procedure may
refer you to the RF Block Diagram, the Gain/Loss table, or both.
Examples:
Verifying the gain or loss of a part – Locate the part in the Gain/Loss table.
Measure the output and input power levels. Subtract the input from the output
to determine the gain or loss. If the part is not meeting the gains or losses
specified (the gain is less than specified or the loss is more than specified), the
part most likely needs to be replaced. In cases where the part fails to meet its
specification but comes very close, calculate and measure the minimum input
power level into the part before replacing the part.
Verifying the minimum power into a part – Locate a point on the RF path
where output power is specified, then use the Gain/Loss table to calculate the
minimum power level at the specific location. If the minimum power level is not
present, measure the output of the first device showing a power level on the RF
Block Diagram, then measure the input and output power level for each device
in the path until the defective part is located.
ALC and RF problems
1. Run a full self–test and troubleshoot any reported failures before
proceeding.
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