4. Measuring Device
Measuring The Effect. Set the QA-ES in test mode by holding
F2 while switching the power on. Connect the signal generator
to the RF input on the sampling unit. The signal applied is a
pure sine of 500 kHz. URE 3 is connected in parallel with the
sampling unit to measure the applied signal. Press START (F3)
and read the measured effect in dB. Vary the level of the ap-
plied signal from -16 dBm to +10 dBm and find the average
value for the difference between the value read on the QA-ES
and the applied value measured with URE 3. Use the term be-
low to calculate a linear percentage value from the difference
value in dB.
KdB: Average value for the difference between the value read
on QA-ES and the applied value measured with URE 3.
Clin: Linear value of kdB.
The following term will lead to a new value for Q_gain.
Turn the wheel and press ENTER to specify a new value for
Q_gain. Repeat the test until the average value between the
QA-ES and URE 3 is smaller than 0.1 dB. This corresponds to
an error of 2.3%.
Peak Detector. Once the measuring device used in measuring
the effect has been calibrated, you can calibrate the peak detec-
tor. Use the same test setup as for calibrating the effect. Mea-
sure with a signal level of 200 mVp and 1 VP applied from the
generator. The applied amplitude is measured with URE 3. The
difference between the value read on the QA-ES and URE 3
should not exceed 10% otherwise the P_offset and N_offset in
the calibration menu must be changed until this requirement is
met. If the positive peak value read is too small P_offset should
be reduced. N_offset should be reduced if the negative peak
value is too low. Press QUIT (F5) to save calibrated values.
5. Measuring Accuracy of the total system. Connect the coaxial
cable from the Load Board to the RF-input (J4) on the Sampling
Unit. Put the ground plate of the isolating box back into place.
Connect a high voltage probe in the port for variable load resis-
tance on the QA-ES. The probe's coaxial cable should be con-
nected to URE 3. The banana adapters of the probe are connect-
ed with the high voltage generator. The following mathematical
formula presents the applied effect in dBm as a curve of the ef-
fect on URE 3.
3
To Next Page
Loading...
Need help?
General
