Bird Technologies 4412A - Manual (Page 11)

1
Chapter 1 Introduction
The Series 4410 Thruline Wattmeter is an insertion type RF wattmeter designed to mea-
sure power flow and load match in 50 ohm RF coaxial transmission lines. Its use
is intended for CW unmodulated, or FM signals only. When used in a 50 ohm
application with N type connectors, the Series 4410 has an insertion VSWR of
less than 1.05 for frequencies up to 1000 Mhz. The meter has two scales, a 0 to 1
scale and a 0 to 3 scale. Power is read as a multiple of the value indicated by the
pointer, the decimal point location depending on the range switch setting and
the factor on the Plug-in-Element. Several of these Plug-in-Elements may be
selected to give this instrument a broad band spectrum with various power
ranges, see Specifications.
Description
The Series 4410 Thruline Wattmeter is a portable unit contained in a die cast
aluminum housing, with a formed sheet aluminum back closure. The unit is
equipped with a carrying strap, four rubber shock feet on the base, and four rub-
ber bumpers on the back, which allow the unit to stand in a vertical or horizontal
position. 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.
Mounted on the line section, inside the housing, is the circuit module with an
attached phosphor bronze spring contact finger, which protrudes through a lat-
eral hole and into the plug-in element socket of the RF line section. The finger
has a button on its end which makes connection 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
wattmeter is inserted. At each end of the line section are Bird Quick-Change
type RF connectors, which may be quickly interchanged with any other Bird
“QC” connectors.