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Richard,nor will that eliminate any rfi (radiated frequency interence).
I don't agree with that either... granted the ambiguity of the term is probably why it doesn't appear in MIL-STD-464. I do agree that if you have a radiated susceptibility (either through an antenna or some other path) that you aren't going to fix it with the power leads. But, lots of bad stuff that is really on the power line either coming into or going out of a device gets blamed on antennas, bad shielding, and "radiated noise". I can even cite a specific example of a PWM stepper motor drive and an ultrasound system (granted, in that case it was both a conducted and radiated susceptibility). Since antennas and receivers are tuned devices, in my experience they are usually the smallest problem, unless you are trying to pick a signal off something that is flying in front of the Sun. I do also agree that "ground" is a confusing term when it comes to anything that isn't actually electrically tied to the earth, so I tend to use "chassis" and "return" when it's important. Who says we don't ever talk about interesting technical topics on SS anymore?John, rfi comes in on the antenna, not on the power leads. I can't think of any thing you can do to the power that will clean up the signal on the antenna. And that includes running off of internal batteries such as with an HT. The Terratrip causes noise even on those if they are close.
Also, as defined on the power systems I work with, there is no 'ground' in an automotive DC power system. In AC systems, the 'ground' is a redundent return path for current in case of a short. The 'neutral' is the normal return path. In automotive systems, the ground is simply the normal return path for current from the positive side of the battery to the negative.
Huh... The good news is that it looks like your filter should be taking care of anything that is coming in on the power line, so it probably really doesn't matter how you route it back to the battery except from a voltage drop perspective. Is the noise a problem when you are receiving, transmitting, or both? Also, are you sure it's the Terratrip? How close are the wires between the filter and the radio to the Terratrip, and how close is the radio to the Terratrip? Google found some complaints on another forum about interference with a CB, so I really doubt it's something coming from the antenna, though the fact that it's frequency dependent gives it some credence. But, that'd be hard to do even intentionally. One other thing you could try is putting the filter on the Terratrip. Is the cable to the pickup two wires or just one? If it's one, that probably won't work.For a filter I'm using the Powerwerx DC line noise filter (http://www.powerwerx.com/adapter-cables/dc-line-noise-filter-oem-t.html). Even with the filter and running both leads to the battery, at NEFR I (also) had some RFI from the Terratrip depending on what radio frequency I was on (somewhere in the 146 range). I didn't have that problem at STPR or Black River (some of the frequencies were close, but not exactly the same). At this point I'll just plan to also run everything straight to the battery.![]()
Since I don't have a Terratrip, forgive the stupid questions, but (1) is the case plastic? (2) is there any part of the case that is metal that is electrically tied to the battery return wire? [can check with an ohmmeter] (3) can you disconnect the sender from the unit? [I am assuming that you have a wheel sensor] (4) do you have any other wires running out of the Terratrip, such as a reset switch? If the answer to (1), (2), and (3) are yes, and the answer to (4) is no or that you can either disconnect or bring all the switches close to the unit, the first thing I would do is disconnect them one by one and see if the problem goes away. If it doesn't (don't laugh...), I'd get some heavy duty tinfoil and wrap the Terratrip in it, making sure that it's completely covered and that that the tinfoil is tied to the metallic part of the chassis. If that makes it go away, this might be a difficult problem to solve.The noise is constant (when sending, receiving, or just listening), and I know for sure it's the Terratrip causing it because when I turn it off (and back on) the noise stops (and starts). The filter is plugged into the factory cord for the radio, so there's about 6 inches of wire between the two (and about half of that is taken up by a fuse). The Terratrip is mounted above the glove compartment and the radio is mounted on the back of the center console/arm rest (between the front seats). Even though they both use separate power wires, the wires enter the cabin in the same bundle, though they split before the filter for the radio.