General Purpose RF Wattmeter
The Bird 43 is an insertion-type RF wattmeter, designed to measure RF power and load match in 50 ohm coaxial transmission lines. It is intended for use with CW, AM, FM, and TV modulation, but not pulse modulation. When used in 50 ohm applications, the 43 has a maximum VSWR of 1.05 for frequencies up to 1000 MHz. The meter provides direct readings in watts with an expanded scale for easy reading. The scale is graduated for 25, 50, and 100 full scale. Elements are available in a variety of power and frequency ranges and are required for operation. Please note, elements are sold separately.
The Bird 43 is portable, with an attached 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 slotted 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.
To make measurements, a Bird Plug-In Element is inserted into the line section socket and rotated against one of the stops. A small catch in the corner of the socket face presses on the shoulder of the element to keep it in proper alignment. This assures good contact between the spring finger and the element contact and between the lower edge of the element and the line section body.