Can you super-size an FM filter?
Teracom Components says yes. The company has introduced what it’s calling a super-sized FM filter for high-power applications. With dimensions of 900 x 1620 x 600 mm, this exceptionally large filter has been developed for special applications in India and North America.
The company says that while it has delivered many similarly sized filters for other applications than FM, this is its largest to date for an FM network. The mechanical design includes temperature compensation for improved stability, which the manufacturer says is not common with models of this size.
The filters are being used in two versions of FM combiners for 80 kW and 150 kW respectively. These combiners have a narrow-band input of 40 kW at minimum channel separation of 1.2 MHz, and include a modified 3 dB coupler in order to handle 150 kW output power. The large and temperature-stabilized cavity of the filter presents new possibilities for building combiners that can offer channel spacing down to 600 kHz and high power, according to Teracom.
The combiners being shipped to India will be used as part of a commercial FM network expansion. The project requires a channel separation of 800 kHz from the same broadcasting antenna.