Telewave Launches Transmitter Combiners for Public Safety and Land Mobile Radio Systems

Telewave has introduced a series of RF power combiners for use in transmitters of public safety and land mobile radio systems operating between 148 to 174 MHz. The M108-150-XTP-M Series combiners for transmitters deliver very high isolation, low loss, and high RF power handling capability. They are designed to meet the demanding requirements of radio systems serving first responders.

The trend toward narrower guard bands between transmit and receive frequencies requires extremely effective filtering to mitigate interference and increase intermodulation suppression between transmitters. Telewave’s transmitter combiners are designed to meet these challenges using very-high-Q, low-loss cavity filters and the company’s T-1560M two-stage isolators that provide extremely high transmitter-to-transmitter isolation and antenna-to-transmitter isolation of 75 dB.

The M108-150-XTP-M Series combiners are designed to accommodate up to 12 channels with one or two transmit antennas. They allow up to 12 cavities to be mounted horizontally on three, 4-channel panels in an optional 19 x 72-in. rack or up to eight cavities mounted vertically in the rack. Vertical mounting can be important if the combiners must be placed in an area with limited space or when mounting on a wall is desired.

Models in the series handle between 100 W and 125 W CW per channel with minimum channel separation of 125 kHz and second-order harmonic suppression of 90 dB. They operate over a temperature range of -30°C to +60°, have a maximum VSWR of 1.25:1, and use female Type-N input and output connectors. Full-surface heat sinks ensure stable thermal management in any environment. One model in the series, the M108-150-8TP-M100, can operate at altitudes up to 15,000 ft. while others are typically usable up to 10,000 ft.

Rack support is provided for an optional Telewave tuner assembly that can be mounted in any orientation in the rack as well as RF power monitoring using Telewave’s PM10C2S1C power monitor that requires only 1.75 in. of rack space for each channel. Remote keying of the transmitter can also be provided. A receiver subsystem can be created using the M108-150 Series, a Telewave preselector, and 1 rack-unit receiver panel to serve up to 16 channels.

The M108-150-XTP-M can be factory mounted in an optional rack and can be paired with an optional power monitor on receive, preselector, and multicoupler. Like all Telewave products for land mobile and public safety applications, electrical and RF specifications of the M108-150-XTP-M Series combiners can be customized to meet specific customer requirements.