Fathom-X Tether Interface Board power question

Can I run power (120V ac or 38V ac) over the tether line that the Fathom-X Tether board uses for communication? Does it have the filters to do that? I just picked up two LX200v20’s that I want to use for making a tether.

I plan on having a battery on the rover but it would also be nice to have an external power feed to keep things charged.

I’m hoping to make a 3000 foot tether.

Any examples with schematics?
Thank you


Have you calculated the voltage drop for the given wire you plan to use at 3000 ft. length? Depending on wire type, gauge, and length, amperage required? it will inform you how much voltage you need to supply the line for the intended voltage to receive at the vehicle. What are your voltage requirements at the vehicle?

More importantly, what specifications for the vehicle do you have? 3000 feet of copper is heavy given gauge and shielding requirements. It will cause a good deal of drag on an ROV even if it’s neutrally buoyant.

If you list out your design requirements, we might be able to work out a solution. You mentioned “rover”, is this a benthic rover project?

More details would help members on the forums to be better able to help you.


We want to explore a part of the canal system that has been built over by the city. the tunnel is about 2000 feet long and drops something like 100 feet in altitude. The walls of the tunnel look to be 2 foot thick concrete. There are waterfalls in it (must be the old locks). It’s very intriguing and changeling.

Currently we are thinking of ways to deal with all the challenges and what type of robot / ROV to build. I expect some testing and redesigns will happen. I figured that the tether would be the best place to start. Since we haven’t started on the rover yet, any power type can be designed in. Are we thinking high voltage AC? hmm, but then we will need a transformer on the other end. We could use high voltage DC with a buck converter on the ROV. My thoughts are to also build a battery system into it. What I want to shoot for, is that the tether would just supply basic power like 120vac, and the rover will have power supplies/s to provide power to everything.

So far where looking at:

  1. Raspbery Pi and camrea
  2. An Arduino to drive motors
  3. Gopro style camera
  4. Lights
  5. 2 power pods (motors with ducted props)
  6. 2 Ducted fans
  7. Tank tracks

We will need to test all this stuff to get an idea of our power draw and calculate what our power requirements will be or the run time to expect :slight_smile: Maybe just use tether power to keep the on board battery charged.

benthic rover? no, I’m hoping that it doesn’t sink.
This is just an exploration ROV. We hope to get video footage of the old canal. It would be cool to get geo location to map the underground tunnel but there is no gps or cell signals down there. We also have a 900 mhz transmitter that we can use. Thinking of using one as a backup tether. not sure how well it will work in a cave.

Very interesting. FYI, radio signals attenuate to zero very quickly in water, so 900MHz will not be an option to communicate to the ROV. Please keep the community updated on your ideas. If you have any photos of the area, that would really help. What are you primary tall poles currently? I’d start from a requirements stand point before making major design decisions like power management until you understand your operating constraints.

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