Over the past three days I have soldered 5 coax cables, with heatshrink tubing to separate the inner and outer, wrapped them in metal foil tape for shielding, wrapped the shielding in electrical tape for isolation, constructed a housing by drilling holes in a 50 mL centrifuge tube, threaded the circuit into the housing, and covered all joints with RTV-108 caulking. It’s drying now. Tomorrow morning I’ll test it to see if it’s watertight. If it is, I’ll be able to start characterizing my first imaging transducer.
RTV-108, by the way, is pretty cool stuff. It’s actually an “acetoxy adhesive”, which cures by exposure to moisture. That means that unlike almost all other glues, it will cure perfectly fine in a damp environment, and actually sets fastest underwater. Chemically, it cures by converting water into acetic acid, so if you breathe on it, it converts the moisture in your breath into vinegar. That means it doesn’t smell too great, but it gets the job done.