AR 10008569, Operating And Service Manual, Page: 16 / 38

Models PH – Power Heads
Figure 1-1. Error Due to AM Modulation (Diode Head)
NOTE: The error shown is the error above and beyond the normal power increase that results from
modulation.
1.3 CALIBRATION AND TRACEABILITY
AR employs both a linearity calibration as well as frequency response calibration. This maximizes the
performance of diode heads and corrects the non-linearity on all ranges.
Linearity calibration can be used to extend the operating range of a diode head. It can also be used to correct
non-linearity throughout a head’s dynamic range, either thermocouple or diode. A unique traceability benefit
offered is the use of the 30 MHz working standard. This is used to perform the linearization. This standard is
directly traceable to the 30 MHz piston attenuator maintained at the National Institute of Standards
Technology (NIST). See Figure 1-2 Linearity Traceability.
Figure 1-2. Linearity Traceability
2 Rev C