I am using an E4419B power meter with an 8481A sensor.
I am measuring the output power of a simple FET and all goes well as I raise the input power from -25 to 0 dBm. The gain is 19 dB.
Pin = 0, Pout = 19 dBm all is fine. Pin = 1 dBm, Pout reads 999.
This is very repeatable. The sensor is good up to 24 dBm so it can't be overload (error -231).
Has anyone seen this before? Any ideas what's going on?
I am measuring the output power of a simple FET and all goes well as I raise the input power from -25 to 0 dBm. The gain is 19 dB.
Pin = 0, Pout = 19 dBm all is fine. Pin = 1 dBm, Pout reads 999.
This is very repeatable. The sensor is good up to 24 dBm so it can't be overload (error -231).
Has anyone seen this before? Any ideas what's going on?
The 8481A is specified to +20 dBm to make accurate measurements. It will measure levels higher (up to +23 dBm) but it is not specified at those poser levels.
The sensor is actually rated for power levels of 300 mW aveage or 15 W peak without damage, but it can't measure the actual power levels at that high a power. You need high power sensors that are designed to measure RF power levels that high.
Since the 8481A is specified for RF power measurements to only +20 dBm (with an overhead of +23 dBm) and power level higher than that are not specified, the power meter is designed to go into overload if the power sensor power level excheeds its maximum capability, in this case with this sensor +23 dBm. That is why you see the '999', that is the overload announcement from the power meter.
This can be dealt with by using a higher power sensors, say a 8481D or 8481B. If the average RF power from the FET is only +19 or +20 dBm, but there is modulation on the RF that is 3 dB higher, the sensor will see the peak modulation signal and cause the power meter to go into overload.
By the way the 8481A/B/D sensors are discontinued and are replaced by the N8481A/B/D.
I hope this answers your questions.