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jetx

As part of a comprehensive electronics upgrade -- system includes Two Axioms, Evolution autopilot, Quantum 2, and multiple i70s and i60 displays -- I installed two new STng smart transducers.. a DT800 and DST800 (A22111 and A22112). I realize that these can't both be operated at the same time without interference, so have only connected one at a time to the STng backbone.

Both transducers are giving me fluctuating depth readings when the boat is sitting still. For example, actual water depth in my slip is about 10.5ft, and about 90% of the time, this is the value I see displayed on my instruments. However, every few minutes, the displayed depth will decrease suddenly, remain (erroneously) low for anywhere from a few seconds to a minute or so, and then gradually revert to the correct 10.5ft reading. The erroneous/low reading is usually 8.5-9ft, but I have seen it drop as low as about 5ft a few times.

I've experienced the same behavior while at anchor in multiple locations. Again, only one transducer is connected at any given time, but both behave the same way. There are no other sounders/fishfinders on the boat, and no other boats nearby when I've been anchored.

The boat is a sailing catamaran, with no keel or other underwater appendages in the vicinity of the transducers. Transducers are mounted in the same location as factory-installed analog B&G transducers (including an older NMEA0183 DT800), which had been functioning perfectly. I've tried a few ferrite chokes snapped onto the STng cable a few inches from the transducer, but didn't see any change/improvement.

I see the same fluctuating depth readings on my i70s and Axioms, and also on a Vesper Watchmate AIS. Since (I believe) all of these are simply displaying/repeating the data that they receive via STng from the smart transducers, that suggests that both transducers are sending erratic data out over the network. Would you agree?

Any troubleshooting help would be greatly appreciated.