The size of the features, and their relative distance to the probe, vary a lot in the intracardiac echocardiography application thus challenging the design of the probe. Therefore it may be beneficial to design a versatile probe which can produce both a large image to provide overview for navigation, and a smaller but detailed anatomic image on the structures of interest. This could be achieved by a probe whose frequency range of operation can be tuned - on the fly - to the specific task. Our goal is to develop a forward-looking catheter which can change its imaging frequency in the range 5 MHz - 15 MHz, allowing for both high penetration and high resolution intracardiac imaging within a single device. Our design comprises a capacitive micromachined ultrasonic transducer (CMUT) array operated in collapse-mode, which allows tuning of the imaging frequency. Custom-made front-end electronics is integrated in a catheter tip close to the CMUT for improved performance. In this paper, we report on the frequency-agility of the fabricated collapse-mode 1-D CMUT array.