Bird Technologies 4314C - Manual (Page 13)

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Chapter 1 4341C Introduction
Purpose and Function
The Model 4314C Thruline Wattmeter is an insertion-type RF wattmeter designed
to measure power flow and load match in 50 ohm coaxial transmission lines. It is
intended for use on CW, AM, FM, SSB, TV, and pulse signals only.
Description
The Model 4314C Thruline Wattmeter is a portable unit contained in a die cast alu-
minum housing. The unit is equipped with a plastic strap for carrying, four rubber
shock feet on the base, and four rubber bumpers on the back which allow the unit to
stand vertical or lie flat in a horizontal position when used. For additional protection,
the meter is specially shock mounted. A slotted screw is provided on the lower front
face of the meter for zeroing the pointer.
The RF line section face below the meter protrudes slightly from the wattmeter
housing with the Plug-In Element socket in the center. The circuit module is mounted
on the line section inside the housing. It has an attached phosphor bronze spring
contact finger, which protrudes through a lateral hole and into the Plug-In Element
socket on the RF line section. The finger has a button on its end which makes con-
nection with the contacts of the Plug-in Element. The silver-plated brass RF line sec-
tion is precision-made to provide the best possible impedance match to the coaxial
RF transmission line in which the wattmeter is inserted. At each end of the line sec-
tion are Bird Quick-Change type RF connectors, which may be quickly interchanged
with any other Bird “QC” connectors.
Performance Characteristics and Capabilities
To make measurements, insert a Plug-In Element into the line section socket and
rotate it to either stop. Point the element arrow in the source to load direction of
power flow and the meter will display a reading of forward power. Rotate the ele-
ment so that the arrow is pointed in the opposite direction to obtain a reflected
power reading. With known values of forward and reflected power the load match
can now be determined by calculating the VSWR or by using the graphs supplied in
this manual (Figure 4 on page 12 and Figure 5 on page 13).
Setting the front panel toggle switch to PEAK mode gives the wattmeter the
capability of indicating peak pulse or envelope power.