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Update on Transmitters
Armstrong is another established presence in transmitters. Its line of solid-state transmitters include the STX, LCD and B series, and are available nearly any power level. The 300W power amplifier is built on the Philips BLF 278 MOSFET. The FMX exciters provide output powers of 30, 150 and 300W. The FMX LCD series of exciters provide outputs of 30 or 100W. The FMX LCD's can be switched between five preset frequencies via remote control.
On the low-power amplifier side, Armstrong offers the FM-300S, FM-500SC and FM-500LCD with power levels of 300 and 500W.
Crown Broadcast, well known in lower power stand-alone FM transmitters, now offers its E Series (built by Ecreso). The E Series features a direct-to-channel integral exciter, and the 350W version occupies 3RU, with 17" of depth. It's a good idea to allow a rack space above and below for cooling purposes. The integral stereo generator accepts L/R analog or AES at up to 192kHz sample rate and up to 32-bit word length. It also has two BNC inputs for composite or SCAs.
An option for the E Series is a TCP/IP communications board that allows for the use of a Web-based interface for monitoring and remote control, along with SNMP support. Use of this optional board also allows support of Crown's Advanced Measurement Interface, as well as a feature known as Expert Maintenance reporting, which is a proactive reporting service that allows for the monitoring of parameters such as temperatures, currents and voltages, plus performance parameters of lifespan-constricted items such fans. These measurements are sent via a regular Internet connection, stored in the cloud and available for analysis by the manufacturer later on, should the need arise.
Bext is also established in FM transmission equipment. For an LPFM application, the LEX series applies, which tops out at 300W. The LEX is a 1RU, frequency-agile transmitter, with integral stereo generator. Output power is continuously adjustable from zero up to the maximum power rating, and it has proportional power fold-back in response to high VSWR. The power supply accepts between 95Vac and 260Vac, which gives some flexibility in the installation. (LEX also includes and FSK ID keyer, should that be needed for translator use.) The LEX series also meets or exceeds FCC specs on spectral purity, and can be used as a stand-alone transmitter.
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