Join Date: Mar 2010
Location: SF - South Bay
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I'm no expert, but did recently replace my transducer with a new in-hull one.
What I learnt was that transducers may look the same, but they operate at different frequencies (and I think different power levels). You need to discover the frequency your depthfinder uses, and match it.
As cghubbell said, pretty well all transducers are made by Airmar, and either sold directly or rebadged by the 'finder manufacturer. if you know the name and model of the 'finder, give Airmar a call. They may be able to advise. And/or try and research it on the web - it's amazing how many 20 or 30-year old manuals can sometimes be found!