Manual - 8500A Series Peak Power Meter - Giga-tronics

Testing and Calibration
5.2.2 Calibrator Return Loss Test
Set up the scalar analyzer, signal generator, and the Return Loss Bridge to measure 0.95 to 1.05 GHz.
Connect the bridge to the Calibrator output on the front panel of the PPM. The return loss must be
>25 dB over the frequency range.
5.2.3 Calibrator Output Level Test
The following test will check the absolute level of the Calibrator function of the PPM. Note that
verifying the level is not the same as setting the level. When the calibrator was previously adjusted, it
was done using equipment capable of setting it to a level within the specifications of the instrument. The
equipment used to verify the value also has its own uncertainties. Due to the nature of the measurement,
equipment does not exist to make it practical to require a ten times (or even 3 times) accuracy difference
between the specified performance and the specified accuracy of the measuring equipment. Therefore, the
uncertainty allowed for this test reflects both the uncertainty of the calibrator and the uncertainty of the
power meter used to verify it.
1. Place the PPM in the CW Mode by pressing [CW], then press [MENU] and select Calibration.
When the Calibration/Zeroing menu appears, press [F1] and then immediately press [7]. Be sure
that the Thermistor Power Meter is zeroed. Connect it to the Calibrator output connection and set
it to the 1 mW range. The calibrator should read 1 mW. To be sure that the measurement is
correct, the following steps must be performed exactly as given. Under no circumstances should
any key be pressed other than the ones specified.
CAUTION
Do not press any UNITS key when the thermistor detector is connected to the
calibrator. This would cause the calibrator to output 100 mW, and would possibly
destroy the thermistor detector.
2. Press [CLEAR], then zero the Thermistor Power Meter.
3. Press [7] and read the Thermistor Power Meter. Take note of the meter reading.
4. Repeat Steps 1 and 2. Average six readings if successive readings are taken.
5. Disconnect the Thermistor Power Meter from the Calibrator connection.
The average reading in Step 3 should be 1.000 mW ±4.5% after correcting for the calibration factor of
the thermistor mount at 1 GHz. Note that an uncertainty smaller than 4.5% can be supported by this
technique if the calibration factor of the detector has been determined by a primary standards laboratory
such as the NIST (formerly NBS). This value merely reflects standard current commercial practice.
5.2.4 Instrument Plus Power Detector Linearity Test
Connect the test setup as shown in Figure 5-1. The linearity will be tested in a series of 10 dB steps over
the range of the instrument. At low power levels, the linearity measurement will reflect the uncertainty
due to the noise specification. Measurements will be made in both the CW and Peak Modes.
Refer to the CW Linearity Data and the Peak Linearity Data sections of the Test Data recording sheets at
the end of this chapter. These sections will facilitate the collection of data for the CW and Peak power
linearity test. The tolerance is already entered in each section for the various steps, and includes an
allowance for specified noise errors at low power levels.
Manual No. 20790, Rev C, November 1998 5-3
Superceded by Revision D, March 2009