Special Messages

As a convenience to the operator and as an aid in servicing, eleven messages can appear in the upper right corner of the CRT display. (Ten of these messages are shown in Figure 1.) Five of the messages inform the operator of possible erroneous data from improper instrument operation. The other six provide warnings of instrument malfunctions that must be repaired for proper instrument operation.

A brief description of each message follows. The troubleshooting information listed is not meant to be exhaustive. Refer to the appropriate Troubleshooting Block Diagram and Troubleshooting Hints for more detailed information.

EXT REF

Indication to operator that the external frequency reference is selected.

MEAS UNCAL

A warning to the operator that the amplitude/frequency data on the CRT is invalid because the analyzer’s sweep speed is too fast for the selected bandwidth.

A warning to the operator that the analyzer settings displayed on the CRT have been changed but the trace data has not been updated. This would occur, for example, when Trace A view is selected and then Center Frequency is changed.

OVEN COLD

Indication that the frequency reference oven temperature is too low. There will be an oven cold indication normally for about 10 minutes after the line power is initially applied to the instrument. (The oven is powered and should stay warm as long as the instrument

is in STANDBY.) The time base HOVC (High = Oven Cold) signal is routed to the Al2 Front-Panel Interface for generation of this message.

BATTERY

A warning to the operator that the CMOS memory on the Al5 Controller has probably lost the stored instrument states. The warning can only appear at instrument turn on. If it appears, the instrument automatically reinitializes all the instrument states to the instrument preset condition. The battery warning can be caused by a problem with the Al5 CMOS memory power supply circuit. Performing the “long POP” instrument check (see RF Section Digital Troubleshooting) erases the stored instrument states and causes a battery warning to appear at instrument turn on. The HP-IB address is also lost. The battery warning can be removed by pressing [GHz’ and the HP-IB address restored by keying in (jZiK) (ZZKj [desired address] [jGiZi?Z).

4 Overall Troubleshooting