Bird Technologies 8920 Series - Manual (Page 8)

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About This Manual
This manual covers the operating and maintenance instructions for the following models:
Changes to this Manual
We have made every effort to ensure this manual is accurate. If you discover any errors, or if
you have suggestions for improving this manual, please send your comments to our Solon,
Ohio factory. This manual may be periodically updated. When inquiring about updates to this
manual refer to the part number and revision on the title page.
Definitions
Measure Match Mode - The Match Measurement mode shows the resonant frequencies
for an antenna or filter. It also confirms that there are no impedance problems in the nonres-
onant components such as cables, connectors, lightning protectors, and jumpers.
Fault Location Mode - The Fault Location mode shows the location of any problems in the
antenna system. This is shown in either feet or meters from the cable end connected to the
Site Analyzer.
Cable Loss Mode - The Cable Loss mode shows the insertion loss of a coaxial cable. By
comparing this with the manufacturer’s specs, it confirms that there are no problems with the
cable.
VSWR - VSWR units used to be the preferred way to measure an antenna system. A good
antenna has a VSWR of less than 1.5:1 at its operating frequency.
Return Loss - Return Loss measures, in dB, how much of a wave is reflected back to the source. It is
now the preferred method for measuring antenna systems. A good antenna will have a return loss of –14
dB or less at the operating frequency. The more negative the reading, the better the antenna.
Markers - Markers are used to show the exact value at one point on the graph. In Measure
Match and Cable Loss modes, the marker displays the frequency and loss (or VSWR). In Fault
Location mode, the marker displays the distance and loss.
Run / Hold - When HOLD is displayed, the unit makes a new sweep every few seconds, and
displays the latest sweep. When RUN is displayed, the unit will only make a single sweep. The
display will not update if the Site Analyzer is disconnected or if the cable is jiggled. This is usu-
ally preferred.
8921 8922 8926 8927
8928 8922D 8926D 8927D