Measurement - Keysight 537A Operating Note

Overview

Measurement

A detector and indicator are required to indicate the dip in coaxial line power at resonance. It is
recommended that 10 dB of attenuation be placed between the signal source and the frequency
meter. If insufficient power is available to use a 10 dB attenuator, an attenuator offering less
attenuation may be used, to a minimum of 3 dB. The attenuator prevents a shift in the frequency of
the signal source due to line impedance changes at resonance.
The detector-indicator combination can be a thermistor mount and power meter such as the
Keysight 478A and 432A, or a crystal detector and SWR meter. If a SWR meter is used as the
indicator, the signal source must be modulated at 1000 Hz (sine or square wave modulation). For
visual display, an oscilloscope can be used as the indicator. When using an oscilloscope for swept
frequency displays, be sure to sweep the oscilloscope at the same rate as the signal source.
Resonance will be noted as a dip in the oscilloscope pattern
Do NOT run dial into stops at either end of dial
CAUTION
If frequency measurement is one part of the measurement procedure, be sure to move meter
off resonance before proceeding with other measurements.
Figure 1
Connectors
The input and output connectors are type-N, female and are compatible with connectors whose
dimensions conform to MIL-C-39012.
N-female Pin Depth: 0.207 to 0.201 in (effective 0 to –0.006)
14
Type-N connector dimensions
Keysight 537A Operating Note