Bird - The RF Experts
4431, Variable RF Tap, Wattmeter

4431, Variable RF Tap, Wattmeter is the same as the model 43 General Purpose Wattmeter with the addition of an RF signal sampler probe. This RF probe provides a low power sample of the signal being measured and is available at the female BNC connector on the right side of the housing. The signal level can be adjusted with a control knob on the front of the meter. The sampled output can be connected to any RF signal monitoring device such as a frequency counter, spectrum analyzer, or oscilloscope.

  • Accurate CW field power measurement while providing a variable RF tap for signal analysis or monitoring
  • Uses industry standard Bird elements with space to store 2 additional within the meter housing
  • Rugged metal housing for the most demanding environments
  • Quick Change (QC) connectors to minimize the need for adapters when making critical measurements
product specifications:
Item No
Item Name
Variable RF Tap, Wattmeter
Power Range
5 kW max. 2-30 MHz
Frequency Range
1 kW max. 30-1000 MHz** using Bird® Plug-in Elements*
Insertion VSWR
with N Connectors 1.07 max.** to 1000 MHz
± 5% of full scale
Insertion Loss
0.1 dB max. (2-512 MHz)
0.2 dB max. (512-1000 MHz)
RF Sample Output
Variable -15 to -70 dB from BNC (Female) port
QC Type (Female N normally supplied)
Light Gray Powder Coat
(H x W x D)
6-7/8" x 5-1/8" x 3-5/8"
175 x 130 x 92 mm
3-1/2 lbs. (1.6 kg)
Within power/frequency range limits stated above
*Quoted accuracy only when used with Bird® Products
**Applies only when coupling is less than 30 dB
compatible devices:
Table 1 - Standard Elements
7/8" Line Section - Standard Elements
Table 2 - Low Power Elements
7/8" Line Section - Low Power Elements
Table 3 - High-Frequency Elements, Entire Table ±8% FS
7/8" Line Section - High-Frequency Elements, Entire Table ±8% FS
Table 4 - Low Frequency Elements
7/8" Line Section - Low Frequency Elements
Table 6 - Milliwatt Elements
7/8" Line Section - Milliwatt Elements
Carrying Case - Portable Thruline®, Load, Signal Sampler, QC Connectors and 4 Elements
Carrying Case - Thruline® Wattmeter, 5 Elements and 1 Small Load
Carrying Case - 12 Plug-In Elements