Transmitter delivers high performance in Land Mobile and Public Safety systems

March 28, 2017 // By Jean-Pierre Joosting
Telewave, Inc., has introduced the M108-150-XTP-M series transmitter combiners that deliver very high isolation, low loss, and high RF power handling capability for use in public safety and land mobile radio applications operating between 148 to 174 MHz.

The trend toward narrower guard bands between transmit and receive frequencies requires extremely effective filtering to mitigate interference and increase intermodulation suppression between transmitters. The combiners on the M108-150-XTP-M 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-inch 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.

“Land mobile and public safety communications systems face interference from co-located sites and a densely-packed spectrum, “said Telewave Chief Executive Officer Robert Bagheri. “Our new M108-150-XTP-M Series transmitter combiners are designed to ensure these systems deliver their full performance and reliability under these difficult conditions.”