Bird 4391M RF Power Analyst Wattmeter

The Bird 4391M is a digital RF Power Analyst designed for measuring peak or average power flow, load match, and amplitude modulation in 50-ohm coaxial transmission lines. It functions as an insertion-type directional wattmeter and is compatible with CW, AM, FM, SSB, TV, and Pulse modulation envelopes. The device utilizes interchangeable Bird plug-in elements to determine the specific frequency band and power range for measurements. It is capable of directly reading Peak Envelope Power (PEP) or Continuous Wave (CW) power in watts, milliwatts, or kilowatts across multiple ranges, as well as Forward and Reflected power. Additionally, the Bird 4391M can compute and display Standing Wave Ratio (SWR), return loss in dB, and percent modulation. The unit is housed in a rugged, calculator-style aluminum case with quick-change RF connectors.

### Technical Specifications

* **Manufacturer:** Bird Electronics
* **Model:** 4391M (Military version of the 4391A)
* **Measuring Medium:** RF transmission in 50-ohm coaxial lines
* **Power Measurement Types:**
* Peak Pulse Power
* Peak Envelope Power (PEP)
* CW Power
* Forward and Reflected Power
* **Supported Modulation Types:**
* CW
* AM (Symmetrical)
* FM
* SSB
* TV
* Pulse
* **Frequency Range:** 0.45 MHz to 2.7 GHz (dependent on plug-in elements) or 450 kHz to 2.3 GHz
* **Power Range:** 100 mW to 10 kW (dependent on plug-in elements)
* **Number of Ranges:** 9 ranges for forward power (2.5 to 1000 full scale) and multiple ranges for reflected power (0.25 to 100 full scale)
* **Accuracy:**
* Power Readings: ±5% of full scale
* SWR: ±10% of reading
* % Modulation: ±5% (with exceptions for high CW power levels: +5% from 0-90%, +10% from 90-100%)
* Return Loss: ±0.3 dB (to corresponding SWR value)
* PEP: ±8% of full scale
* **Usable Over-Range:**
* Up to 120% of scale on CW, PEP, SWR, and Return Loss functions
* Up to 400% of scale (PEP) on dBm and % Modulation functions
* **Impedance:** 50 ohms
* **Insertion SWR:** 1.05 max to 1000 MHz
* **Pulse Parameters (Square Pulses):**
* Pulse Width: 0.8 µsec minimum
* Repetition Rate: 25 pps minimum
* Duty Cycle: 0.01% minimum

### Interfaces

* **RF Connectors:** Standard Bird Quick-Change (QC) Female N-type. Optional: Any standard AN “QC” type.

### Physical Characteristics

* **Dimensions:** Approximately 4.38″ high x 9.63″ deep x 6.25″ wide (111mm x 245mm x 159mm) including connections
* **Construction:** Aluminum calculator-style case, shock-resistant keyboard and range switches, RFI protection
* **Weight:** 5.75 lbs (2.6 kg)

### Electrical Characteristics

* **Input Power Requirements:**
* Voltage: 100-130 Vac or 200-230 Vac (Switch Selectable)
* Frequency: 50-60 Hz
* DC Input: 7.5 Vdc (internal battery)
* **Power Consumption:** 6 Watts
* **Batteries:** 6-1.25 V Nicad C size. Rechargeable nickel-cadmium batteries. Manual recommends NiMH batteries.
* **Battery Life:** Approximately 8 hours

### Compatibility

* **Meter Compatibility:** Designed for use with Bird RF power meters and compatible Bird meters [User Input]. The 4391M is a standalone RF Power Analyst that measures power flow.
* **Plug-in Elements:** Requires Bird Plug-in Elements for specific frequency and power range measurements. Accuracy is not guaranteed with components not supplied by Bird Electronic Corp.. The element with the lowest possible power range that will not result in over-ranging should be chosen for greatest accuracy. Two elements in a 10:1 power ratio may be used for some modes.

### Operational Features

* **Measurement Modes:**
* Continuous monitoring of maximum and minimum readings
* Peaking aid
* Error messages
* Recall lowest or highest reading from memory
* Comparison of newest reading to previous reading
* **Internal Processing:** Microcomputer-controlled with extensive program stored in permanent memory for error detection, correction, and data refinement. Can compute VSWR, amplitude modulation, and various decibel variables for consistent and repeatable measurements.
* **Field Use:** Portable and suitable for field or laboratory use.

Why Choose Aumictech for Bird 4391M?
At Aumictech, we specialize in supplying high-end RF and microwave test equipment. Whether you need precise power measurements, accurate load matching analysis, or detailed amplitude modulation characterization, our team ensures the Bird 4391M delivers maximum performance for your application.