456 Chapter9
IF Section
A5 IF Assembly
CAUTION For troubleshooting, it is recommended that you use an active probe,
such as an 85024A, and another spectrum analyzer. If an 1120A active
probe is being used with a spectrum analyzer having dc-coupled inputs,
such as the 8566A/B, 8569A/B and the 8562A/B, either set the active
probe for an ac-coupled output or use a dc-blocking capacitor between
the active probe and the spectrum analyzer input.
CAUTION Do not short control voltages to ground. These voltages are not
short-circuit protected. DACs damaged by shorting these voltages
might not fail until several weeks after the shorting takes place.
Do not short power supply voltages to ground. The 8564EC or
8565EC spectrum analyzer power supply current limiting cannot
protect the resistors in series with the power supply.
NOTE Some transistors have collectors connected to the case. Electrical
connection of the case to the collector might not be reliable, making
collector voltage measurements on the transistor case unreliable.
IF Signature
1. Disconnect W27 (coax 3) from A5J5.
2. Connect an SMB tee to A5J5, using a short coaxial cable with SMB
connectors.
3. Connect one output of the tee to cable W27 (coax 3).
4. Connect an 85024A active probe, with a 10:1 divider installed, to the
other output of the tee.
5. Connect the output (type N connector) of the active probe to the
input of the 8566A/B spectrum analyzer.
6.Connect the probe power cable to the 8564EC or 8565EC
spectrum analyzer front panel PROBE POWER connector (you may
need to use a probe power extension cable, 10131B).
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