Ground Loop with satellite coax

[mccoady]

I have a ground loop in my system that's being caused by the coax cable running from the dish to my Direct Tivo. If I unplug both coax runs the buzz goes away, does anyone have any suggestions on how to eliminate the hum? I had a ground loop when I used to have cable and I used a ground loop isolator but I keep reading with satellite you shouldn't run anything inline between the dish and receiver. Any suggestions?

[John T Smith]

Check the end connectors VERY carefully... all it takes is one very tiny part of the coax wrapping in the wrong place to have interference problems

[goony]

If you have access to a voltmeter (and are comfortable using such equipment near a power outlet), measure (using the AC volts range) the outside of one of the "F" connectors on the back of the DTivo compared to the ground prong hole of the power receptacle that you are plugging the DTivo into. The goal is to see if there is a voltage difference between the DTivo chassis and the wall outlet ground.

If there is more than a few volts then something is amiss within the DTivo. Also compare the wall ground to the outer part of the cable coming from the dish itself. The source of the voltage has to be the dish or the DTivo itself.

Another possibility is that your power receptacle doesn't provide a good ground. To prove that, remove your DTivo and plug it into an outlet somewhere else in the house and repeat the above test with the voltmeter. If you get a different reading then suspect the power outlet ground at the original install location.

One fix might be to use one of those 2-prong male to 3-prong female ground adapters on the cord of your DTivo - that would cause the DTivo to 'float' and it might fix the problem, but don't use that option if the voltage during the troubleshooting steps above was more than 10 volts AC. The last thing you want is ungrounded equipment presenting a shock hazard via their metal case.

Finally, it is possible that the source of the stray AC could be the TV set or other gear that the DTivo is feeding - experiment with the video output cables removed as well during the above test steps.