Bird Technologies 4527 - Manual (Page 43)

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Bird 4431 Thruline Wattmeter
The Bird 4431 RF Sampling Wattmeter is the same as the Bird 43 Thruline Watt-
meter except for an RF signal sampler probe.
The RF sampler provides a low power sample of the signal being transmitted
through the wattmeter’s linesection. This signal is available at the female BNC
connector labeled “RF SAMPLE”, on the right side of the housing. The signal level
can be set with the control knob on the front of the meter. The table below lists
approximate attenuation levels, and notes maximum suggested adjustment. The
sampler output may be fed to any suitable RF signal monitoring device; e.g. a
frequency counter, spectrum analyzer, or oscilloscope. All other operation
instructions are the same as for the Bird 43.
Maintenance
Do not make repairs to the probe assembly. If the sampler malfunctions, we rec-
ommend returning the unit to the Bird Service Center for repair. To replace the
probe assembly, follow these instructions:
1. Access the probe by unscrewing the four 8-32 flat head screws that secure
the back cover.
2. Grasp the back cover by the side tabs behind the line connectors and pull
straight backward to remove it.
3. Remove the small coupling control knob on the front of the wattmeter with
a 1/16 hex socket wrench.
Sampler at max
(Fully clockwise)
Turned counter-
clockwise 4 full
turns from max*
Turned counter-
clockwise 7 full
turns from max*
Freq.
(MHz)
Atten.
(dB)
Freq.
(MHz)
Atten.
(dB)
Freq.
(MHz)
Atten.
(dB)
2 69 300 38 800 36
10 57 400 34 900 35.5
25 46 500 30 1000 35
50 42 600 29.5
75 39 700 29 * Approximate
attenuation
100 36 800 28.5
200 31 900 28