Mechanical filters for FM mobile applications

The Western Division of Collins Radio Company has developed an electromechanical bandpass filter for use in the low frequency IF of split channel FM mobile receivers. The "Mobile" Filter has a 455 kc center frequency and nominal 3 db and 60 db bandwidths of 13 kc and 28 kc respectively. The filter is fixed tuned, enclosed in a third of a cubic inch package and was engineered with the idea of low price without compromise in performance. The Mobile Filter gives both the equipment designer and user excellent selectivity and stability, so essential when operating under split channel conditions, along with a flat amplitude response and low loss.