Tether with 2 twisted pairs again: lessons learned


My adaptor for ethernet over power (tplink TL-PA201) was not working properly. I hacked it and injected 3.3V somewhere following a discussion on openrov.com. I got all the green LEDs, but there is no communication. I thought to just use two twisted pairs instead (and save the power an adaptor consumes) and a standard ethernet TCP-IP connection. I sealed 2 pair through the body and used hot glue to keep the pairs together every meter. Effectively I made a 20 meters patch cable. It sinks to the bottom without floats so you need a flat seabed. However I decided to increase the length and solder another 20 meters to the end. After soldering there was no signal anymore. The soldered joints will increase the impedance and increase the electrical magnetic interference EMI. Removing some twist from the cable also doesn’t do any good. Now I need to remove the sealed tether and insert a new, or buy a Tenda adaptor. So in short:

  • two twisted pairs works fine as tether, but:
  • You can’t solder UTP on a long tether if you use TCP/IP
  • therefore it’s not simple to repair or change the length of the tether
    Reason for me to buy the Tenda adaptor. If you have any tips to make a waterproof joint in UTP let me know!