Fixed Single Element RF Wattmeter (Includes 4304A-1 Element)
The Bird 4304A Wattmeter is an in-line sensor that measures RF power and load match in 50-ohm coaxial transmission lines. It can be used with CW, AM, FM, and TV modulation, but not pulse modulation. It is supplied with a special broadband element with a frequency range of 25 to 1000 MHz. It can measure up to 500 W, depending on the frequency, and has a maximum VSWR of 1.07 with the standard “N” connectors. A range switch allows the full-scale power to be reduced for greater accuracy.
The wattmeter is portable, with an included carrying strap. It has an aluminum housing and an easily removed back cover, with bumpers on the base and back that allow the meter to stand or lie flat. For additional protection, the microammeter is specially shock mounted. A screw on the lower front face of the meter is used to zero the pointer. Below the meter face, the RF line section protrudes slightly from the wattmeter housing with the element socket in the center.
The RF line section is precision machined to provide the best possible impedance match to the transmission line under test. A formed phosphor bronze spring finger protrudes into the element socket to make contact with the element. At each end of the line section are Bird Quick-Change RF connectors that may be interchanged with any other Bird “QC” connector. The wattmeter housing does not interfere with connector changes.
Combining the Thruline Wattmeter with a Bird Termaline Load Resistor creates an accurate absorption wattmeter. With this combination, readings only need to be taken in the forward direction because the reflected power will be negligible.