Rohde & Schwarz Smart Instruments UP300, Operating Manual

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R&S UP300/350 Warnings Indicating Impermissible Operating States
Operating Manual, 11/2007 8-347 E-1147.2759.00
8.2 Warnings Indicating Impermissible Operating States
Warnings Red labels in the status line tell the user that the measurement results may
be incorrect. This can be caused by excessively high signal levels at the input
or by incorrect settings on the instrument. The warning remains on the screen
until the problem has been eliminated.
There are several types of messages that can be displayed on the screen.
OVL G
The output current of the R&S UP300/350 is too high. This can be caused by
the following:
1. The load impedance is too low at high output levels. Eliminate any short
circuits.
2. A noise voltage is being supplied at the output connector. Remove the
voltage source.
The output concerned switches off if the error lasts for longer than 2
seconds. The output should be switched on again after the error has been
eliminated (
Ê 6-104).
OVL A The input level of the R&S UP300/350 is too high. This can be caused by the
following:
1. The input level changes rapidly by 1 to 2 measurement ranges. The
warning disappears after the measurement range has been reconfigured.
2. The input level exceeds the fixed level range (Fixed Range). Readjust
the level range (
Ê 6-105).
3. The input level exceeds the value V
rms
> 33 V. Reduce the input level.
PLL The control loop, which is used to set the frequency of the internal reference
oscillator with crystal accuracy, is not locked. This causes a frequency error,
and the audio analyzer no longer operates according to
specifications. The cause for this may be an internal instrument error or the
absence of the 10 MHz reference signal at the external input REF IN. The
absence of the reference signal, however, is not indicated unless the
reference has been switched to “external”.
1. If the missing external reference signal is the cause of this error
message, connect a 10 MHz signal to the REF IN [23] input or switch the
reference to “internal” (
Ê 6-331).
2. If the missing external reference signal is not the cause of this error
message, an internal instrument error has occurred. In this case, switch
the instrument off and on again. If the error message is still present, the
instrument must be sent to the service shop to be checked.
OVT An impermissibly high temperature was detected in the instrument. The
internal fans are switched to full power for approx. 2 minutes, and then the
R&S UP300/350 is automatically switched off to prevent further overheating.
The overtemperature could be caused by too high an ambient temperature
and/or a reduced air circulation.
1. Allow the instrument to cool off for a while and remove any
obstructions that could prevent the R&S UP300/350 from air circulation.
2. If this does not eliminate the overtemperature, have the instrument
checked by the service shop.