Bird Technologies 4331 - Manual (Page 16)

the base, and four rubber bumpers on the back, which allow the Model 43
to stand (vertical) or lie flat (horizontal) when used. For additional protection,
the microammeter is specially shock mounted. A slotted screw is provided
on the lower front face of the meter for zeroing the pointer. Below the meter,
the RF line section face protrudes slightly from the wattmeter housing with
the Plug-In Element socket in the center.
A shielded cable connects the microammeter to the dc jack which is attached
to the side of the RF line section casting. This cable, 32 inches long, permits
removal of the RF line section from the wattmeter housing. Meter connections
may be maintained with any installations outside of the housing.
Inside the dc jack assembly, there is a filter capacitor which shunts the meter
circuit to prevent misreadings caused by stray RF energy existing in the
Plug-In Element. Mounted on the dc jack is a phosphor bronze spring finger,
which protrudes through a lateral hole and into the Plug-In Element socket
of the RF line section.
The spring finger has a button on its end which mates with the contacts of
the Plug-In Element. The silver plated brass RF line section is precision
made to provide the best possible impedance match to the coaxial RF
transmission line in which the Model 43 is inserted. The ends of the line
section are nested in mating slots to provide additional mechanical support.
At each end of the line section are Bird Quick-Change (QC) type RF
connectors, which may be quickly interchanged with any other Bird “QC”
connector by removing the four screws on the mounting flanges. The watt-
meter housing does not interfere with any connector changes.
To make measurements, the cylindrical shaped Plug-In Element is inserted
into the line section socket and rotated against one of the two stops. A small
catch in the upper right hand corner of the casting face presses on the
shoulder of the Plug-In Element to keep it in proper alignment and assure
a good contact with the dc jack and between the lower edge of the element
and line section body, refer to figure 1.
Bird Model 43 Wattmeter
2