Modern, Efficient, Digital/Analog High Power
Nautel invented the modern solid state broadcast transmitter over 40 years ago. Five generations of transmitter design know-how have been applied to the NX Series resulting in the most modern and reliable high power transmitters available today.
- AM precorrection, unmatched linearity
- Industry?s top efficiency: up to 88%
- 1.8 MHz direct digital modulation
- Powerful AUI web control
- 17? intuitive touch screen interface on 25/50 kW
- 100% remote web access to the user interface
- RF and audio spectrum analyzer
- Trimode: Analog, HD Radio, all DRM modes
- The new standard in compact AM design
The building block of the NX Series is an integrated RF amplifier/modulator with a carrier power capability of 2,500 W. These power modules are hot pluggable from the front of the transmitter making service easy.
The Class-D RF amplifier uses four transistors that can be replaced using only a screwdriver. Due to advances in amplifier technology, this amplifier is so efficient (98%) that it is capable of operating at over 10 kW continuously.
This power capability results in very low transistor junction temperatures assuring robust operation even in the highest ambient temperatures.
ROCK SOLID RELIABILITY, ON-AIR
SERVICEABILITY THROUGH REDUNDANCY
NX Series transmitters are ruggedly engineered to provide easy on-air service and maintenance.
An NX25 uses 10 high capacity modules while a 50 kW NX50 has 2 individual modules. Using numerous high capacity modules affords the utmost in reliability and on-air power output consistency.
In the NX50, 2 amplifiers combine to deliver up to 75 kW of average power (carrier plus modulation). At all power and modulation levels, all modules contribute equally to the final output. If an amplifier fails, no stress is imposed on the remaining modules and spectral integrity is not compromised.
Repair or replacement can be performed whenever it is convenient. Ventilation is provided by redundant brushless DC ball bearing fans mounted in removable trays below the power modules.
Airflow is unaffected by AC supply variations, further ensuring cool operation and long term reliability. Even the exciter is duplicated and automatically switches to the standby exciter in the event of an RF drive failure.
BUILDING THE INDUSTRY?S
BEST DIGITAL TRANSMITTER
To design the industry?s best digital transmitter our engineers applied two guiding principles:
- First they designed a transmitter so linear that no pre-correction would be needed.
- Then they pushed the limits of transmitter design by adding the best digital pre-correction available.
NX transmitters achieve outstanding linearity by employing a unique six phase Direct Digital Modulation that is encoded at an unprecedented 1.8 mega-samples per second. NX Series pre-correction corrects for all primary forms of distortion which typically affect both analog and digital AM broadcasting.
Specific pre-correction techniques include:
- Envelope equalization
- AM-AM correction
- AM-PM correction
All pre-correction filters can be monitored from the front panel display. The result is an ultra linear digital broadcast transmitter design that is scalable from 3 kW to 2 MW. The inherent linearity means that your NX transmitter is prepared for the future. Analog, all modes of DRM 30 or HD Radio are all supported today in this tri-mode design.
POWER EFFICIENCY: ENERGY SAVINGS
AND CLEANER ENVIRONMENT
Exceptional efficiency and low maintenance overhead make this transmitter extremely cost effective to own and operate. Overall efficiency is typically 86% or better.
High efficiency means less energy is wasted as heat, which reduces cooling and ventilation costs. The resulting savings could amount to tens of thousands or even hundreds of thousands of dollars over the life of your transmitter depending on its size and your local power rates.
Efficiency also results in the ability to reduce green house gas emissions by thousands of metric tons over the life of your NX transmitter.
NX transmitters come standard with free MDCL power saving technology as pre-installed software (i.e. not an optional circuit board).
CLASS LEADING SPACE EFFICIENCY
NX Series transmitters are typically one half to one quarter the size of comparable high power medium wave transmitters. That makes planning your NX transmitter deployment that much easier and gives you flexibility too.
While NX Series transmitters may be compact they still offer easy and spacious access to all major serviceable components and modules ensuring easy maintenance.
ADVANCED CONTROL AND
All NX Series transmitters include Nautel?s Advanced User Interface (AUI) with web access. NX15, NX25 and NX50 transmitters come with a 17? touch screen monitor. Whether you are on-site in front of your transmitter or at home on the web, 100% of the AUI is available to help you manage your transmitter.
Hundreds of parameters are available in real time at your fingertips. Imagine knowing in advance what parts and tools you?ll need at the transmitter site. Having that much control remotely can help you avoid trips, save time and save money.
The touch screen interface is implemented as a noncritical functional unit and may be completely removed from the system without affecting transmitter operation.
Support is also provided for SNMP and traditional direct wired contact closure capability for local or remote control.
Some of the features of the AUI include:
- Real-time impedance locus measurement
- Instrument grade spectrum analyzer
- IBOC modulation analyzer
- Module level monitoring and control
- Logging of all functions
- 100% Remote Access
REAL TIME BUILT-IN INSTRUMENTATION
NX Series transmitters are provided complete with built-in instrumentation that would cost tens of thousands of dollars if purchased separately.
Included is Nautel?s patent pending, real-time impedance measurement technology that allows the antenna system load impedance to be optimized and monitored while the transmitter is operating normally. The transmitted voltage and current waveforms are compared to measure the load impedance over the operational frequency range.
Because this system can measure impedance without requiring artificial swept tones, the antenna system impedance locus can be measured without taking the station off-air. Impedance is measured at the combiner so no correction for harmonic filter phase is required.
NX transmitters also include a built-in directional coupler for spectrum measurement. Traditionally transmitters have utilized a voltage or current sensor. The directional coupler increases the accuracy of spectrum measurement into a real antenna load which is quite important when measuring adjacent channel emissions.
OPERATIONAL EASE, PROVEN RELIABILITY
AND EASE OF OWNERSHIP
Like every Nautel ever built, the NX Series incorporates solid state components in a rugged, highly redundant, hot swap architecture. Compact footprints, published parts lists and screw driver replaceable power FETS make living with your NX transmitter easy for years to come.
A unique feature of Nautel AM transmitters is the complete duplication of the exciter section, providing RF carrier and modulation control signals to the power modules (optional on NX3, NX5 and NX10). Should a failure occur, the transmitter automatically switches over to the built-in standby exciter, dramatically enhancing the already high operation reliability inherent in the modular solid-state design.
NX transmitters are also designed:
- to stay on the air without human supervision thanks to a high VSWR threshold of 1.5:1 and automatic fold back in more extreme VSWR situations,
- with a unique circuit which dynamically stabilizes power against AC line voltage variations ? after an AC power loss, over voltage or RF overload, prior operating status is automatically restored,
- for fast simple frequency change capability without the need of special tools or external test equipment.
SAFETY WITHOUT COMPROMISE
The standard features of the NX Series meet safety standard EN60215.
Locking NX transmitter cabinet front and rear doors ensure authorized-only access to critical or dangerous circuitry.
Optional safety upgrade allows the system to greatly exceed EN60215 standards. This equipment consists of a mechanical key-controlled access system that ensures power is removed from the transmitter cabinets and the antenna is grounded before allowing access.
A fail-safe, emergency shut down system is included that allows an unlimited number of series connected safety shut off switches to be added. Any loss of electrical continuity in this loop will automatically cause the main AC circuit breaker to open, removing all power from the transmitter cabinet(s).