I am involved in a San Juan 23 restoration project at the Calgary Yacht Club in Alberta, Canada. I have enclosed photos of the sonar transducer. There appear to be 2 transducers: a brass colored (presumably monotone) transducer and a bronze externally threaded chirping transducer. The monotone transducer was hooked up to a Standard Communications DS100 depth sounder (according to the circuit board, but the best manual for the device I can find seems to indicate that it is a Standard Horizon DS150 sounder). The club managed to save the circuit board for the device, but the console cover is missing. What other makes and models of sonar could be hooked up to the (presumably monotone) transducer? Is the Standard Horizon/Communications sonar a chirping sonar? What makes of device could the club hook up to the bronze externally threaded transducer, which is not hooked up in the enclosed photos? Is the bronze transducer a chirping transducer? - Ian Douglas