Bird Technologies 4331 - Manual (Page 38)

General
Measurements are made by the insertion and operation of the Plug-In
Elements. The elements determine the power range to be read on the meter
scale, and the major marking (e.g. 50 W, 100 W, etc.) are the full scale power
value for the element. Elements are also marked for frequency range. The
transmitter frequency must be within the band of the element used. Refer
to the Bird Catalog for a large selection of elements.
Refer to the Frequency Response paragraph for frequency band flatness and
performance of the elements outside of their stated frequencies. Elements for
additional ranges (power or frequency) may be ordered without returning the
Model 43 for calibration, since the RF bodies and meters are standardized,
and are designed for a wide range of coaxial transmission power value and
frequencies.
The “arrow” on Plug-In Elements indicate sensitive direction; i.e., the direc-
tion of power flow which the meter will read. “Arrow” and “Reverse” are
directional terms used in reference to the Thruline Wattmeter Element, and
mean respectively the sensitive and insensitive directions of the element.
Rotate the element to reverse the sensitive direction. “Forward” and “Re-
flected” are directional terms used in reference to the source-load circuit. The
transmitter may attach to either connector of the wattmeter. It makes no
difference which external RF connection is selected, since the elements are
reversible and the RF circuit is symmetrical end for end. Refer to figure 10.
The Thruline Wattmeter used with a Termaline Load Resistor of proper
power rating forms a highly useful absorption wattmeter. With the “arrow”
set toward the load, it is unnecessary to reverse the element, because the
reflected power should be negligible.
Bird Model 43 Wattmeter
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