Nautel NX3 – 3kW AM Transmitter

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The NX3 stands apart compared to other 3kW AM transmitters on the market today with efficiency of 86%, compact enclosures that are 1/3 to 1/4 smaller, and digital transmission capability.

Front panel control of the new NX3 transmitter is via an easy-to-use LCD display. Like other members of the NX Series, it also includes Nautel’s award-winning Advanced User Interface (AUI). Log in to the AUI on the NX3 using a web browser on your PC or mobile device to gain access to unprecedented instrumentation and control whether you are at the transmitter site, the office or home.



AUI’s functionality includes built-in commercial grade instrumentation, full remote access; SNMP support; an instrument-grade spectrum analyzer and network analyzer; real-time modulation error ratio measurement; monitoring and control including event logging; email and SMS notifications; backup audio via streaming and USB playout; presets and enhanced support services including Nautel Phone Home.

Analog, DRM and HD Radio models are available.

Technical Specification

Technical Specification

Transmitter Type

  • Medium wave, AM, 100% solid state


  • Four RF power modules, each including a single integrated RF amplifier/modulator
  • No frequency dependant parts in RF module
  • Each module is hot pluggable and has internal microcontroller for protection and monitoring over a serial bus
  • Short circuit protection at the module level offers an added layer of protection
  • Optional redundant digital single board exciters utilizing FPGA/DSP technology with automatic changeover
  • Pre-correction utilized specifically to improve digital performance

RF Output Power

  • Carrier Power Range: 0 to 3300 W
  • Up to 62 preset levels, presets may include other operational parameters such as DRM vs analog and different program inputs
  • Output level stabilized against AC supply voltage variations
  • Built in Dynamic Carrier Control
  • Built in AM stereo

RF Output Connection

  • 7/8″ EIA or 1-5/8″ EIA

RF Output Impedance

  • 50 ohms, unbalanced


  • 82% typical at 3 kW


  • 800 peak reflected watts (1.7:1 VSWR @ 3 kW, 100% modulation) results in instantaneous power shutback
  • 200 reflected watts RMS (1.7:1 VSWR @ 3 kW, 0% modulation) results in a graceful power reduction

Frequency Range

  • 531 kHz to 1,700 kHz.”Quick frequency change capability”

Frequency Stability

  • ±2 ppm/year over temperature range
  • ±0.3 ppm/year with GPS option

Modulation Capability

  • 140% positive peak modulation to 3000 W
  • 130% positive peak modulation to 3300 W

Spurious and Harmonic

  • Meets ITU-R SM.328-11
  • Meets ITU-R SM.329-12




  • 208 Vac & 380 Vac, 3 phase or to customer specifications

Power Supply Variation

  • ±10% voltage, 47 Hz to 63 Hz



Temperature Range

  • 0°C to + 50°C
  • Derate 3°C per 500 m above sea level
  • (2°C per 1,000 ft)


  • Forced Air

Humidity Range

  • 0% to 95% non-condensing


  • 0 m to 4,000 m (0 ft to 13,000 ft)



  • Meets EN60215: 1996 Safety Requirements for Radio Transmitting Equipment



  • Dimensions – 2 cm H x 58.7 cm W x 86 cm D (72.5″ H x 23.1″ W x 34″ D)
  • Weight – 261 kg (573 lbs)



Analog Broadcast Inputs

  • Dual AES-EBU Digital Audio inputs* adjustable from -30dBFS to 0dBFS for 100% modulation
  • 600 ohms balanced analog audio input +10 dBm nominal for 100% modulation, adjustable from -10 to +12 dBm

Digital Broadcasting Inputs

  • I,Q over AES-EBU* with sample rate converter
  • I,Q over LVDS, 3 pairs, Clock, Data, frame sync
  • *Two AES-EBU inputs provided and may be used for either analog audio or digital I,Q inputs
  • External Generator/Content Server required for DRM broadcasting
  • Optional Integrated HD Radio Generator (Exgine™)

Frequency Response

  • +0.2 dB/-0.8 dB, 30 Hz to 10,000 Hz.
  • Configurable audio input filters available to meet regional bandwidth restrictions

Total Harmonic Distortion

  • Better than 0.8% (THD), 1 kHz tone at 95% modulation (typical)

Intermodulation Distortion

  • SMPTE 1:1 Ratio, 60Hz/7kHz, 95% Mod Peak – 0.5% @ 5 kW (typical)
  • DIM-B, 2.96kHz/9kHz, 80% Mod Peak – 0.5% @ 5kW

Carrier Shift

  • 5% or less

Hum and Noise

  • -65 dB or better below
  • 100% modulation at 5 kW



Extensive Control/Monitoring/Troubleshooting system through Advanced User Interface (AUI) available over the internet from any web enabled device. Local control available via front panel LCD. Built in instrumentation providing detailed spectrum/impedance and modulation analysis.



  • DC Voltages (B+, PA and 15V)
  • DC Current
  • Sample Levels (PDM and RF Drive)
  • Fan Speeds
  • Heat Sink Temperature


  • Output Current (RMS, Peak, Carrier)
  • Output Voltage (RMS, Peak, Carrier)
  • Forward Power (RMS, Peak, Carrier)
  • Reflected Power (RMS, Peak, Carrier)

RF Monitor

  • RF monitor is a power sample (using a directional coupler) that will allow for accurate audio performance measurements


  • Easy access to current transmitter operating state, past and present alarm conditions and historical trends of both digital and analog channels


  • Intuitive easy to read built in scheduler
  • Up to 144 yearly rules can be defined by user

Remote Control/Monitoring

Three Remote interfaces:

  • Direct wired optically isolated inputs and open collector outputs
  • Web interface – All locally available control is available over TCP/IP web interface
  • SNMPv1

Notes: Specifications defined in a laboratory environment with high grade source and demodulation equipment. Standard factory measurements do not include all items.


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