Bird Technologies 4201 Series - Manual (Page 11)

Chapter 1
Introduction
Wattmeter
Purpose and
Function
The 4201 Series Multi-Channel RF Directional Wattmeter is used in conjunction
with Bird Power Sensors, or rigid line sections and elements. Together these
components build a RF power measurement system capable of displaying RF power
of up to 24 transmitters, depending on the model used. Dual meters simultaneously
display forward and reflected power in a 50 ohm transmission line.
Theory of Operation The Series 4201 Multi-Channel Wattmeter accepts dc inputs from remotely located
Bird Power Sensors, or rigid line sections with elements. Forward and reflected
signals are applied to a manual switching network which selects one of 12 or 24
channels. The output of the switching network is connected to the meters for direct
readout. The meter scaling is in accordance with input requirements and must be
the same for all inputs to the wattmeter. Refer to figure 1.
The Model 4201 wattmeter is a panel mount type. These units are intended for fixed
installation, generally in rack mounts requiring 19 inch panels. A slotted screw is
provided on the lower front face of the meter for zeroing the pointer. The rotary
switch (or switches) on the front of the panel, is for selecting the channel to be
monitored. The Models 4201A501 and 4201A502 have an enable/disable push button
switch. The Models 4201A503 and 4201A504 have an A/B push button switch.
FWD RFL
Rigid
Line
Power
Sensor
Power
Sensor
FWD
RFL
Channel
1
Channel
2
Channel
24
FWD
FWD
RFL
RFL
FWD
RFL
Figure 1
Block Diagram
1