Agilent Technologies 856290216 service manual RF Path Fault Isolation

RF Path Fault Isolation

RF path fault isolation checks high-band RF paths. (Automatic fault isolation checks the low-band RF path.) An external microwave source with a frequency range of 5 GHz to

13.2GHz is required. The source is not controlled over HP-IB. The user is prompted by the TAM to set the source to 5 GHz at -10 dBm. (The TAM expects -10 dBm at the input of the spectrum analyzer; the amplitude at the source output may have to be higher to account for cable loss.)

The source also provides a signal for high band. The TAM checks the operation of the A9 input attenuator. The TAM checks the A10 YIG-tuned filter/mixer at 5 GHz. If no signal is present, the TAM will use the 298 MHz SIG ID oscillator, if present, as is done in AFI.

Calibration Oscillator Troubleshooting Mode

The cal osc troubleshooting mode enables front-panel control of the cal oscillator on the A4 assembly. The cal oscillator can be fixed-tuned to three different frequencies. The cal oscillator may also be set to one of four sweep widths, centered at 10.7 MHz. Fixed-tuned settings:

11.5MHz

10.7MHz

9.9MHz

Sweep-width settings:

20kHz

10kHz

4kHz

2kHz

The cal osc troubleshooting mode sends the cal oscillator output (-35 dBm) to the A5 IF assembly. On the A5 IF assembly all crystal filter poles are shorted, all LC poles are enabled, and the 15 dB attenuator is disabled. Signals from the RF section are attenuated as much as possible.

7-16 General Troubleshooting