Isolating RFI noise

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10-09-2009, 06:53 PM
Cane Pole

Isolating RFI noise

Isolating RFI problems.

Use a RFI noise sniffer. Most folks have one and don’t even know it.
The laymen name for the sniffer is called an AM radio.
Turn on your electronics. Turn on your hand held AM radio. Cheap radio works good.

Select a good conservative talk show. Move the radio around the boat wires in the boat and it will pick up the static source. The loudest static is the source of the noise.

Note that liberal talk shows won’t work as it is all static.:rolleyes:

Take notes on this you HB reps. :)
10-10-2009, 11:11 AM
Humminbird_Greg

Would that be the liberal talk shows part or the static?
Is there really a difference? :eek: :D :D
10-10-2009, 11:45 AM
Barnacle Bill

I use to know that. Completely forgot how handy an old transitor radio was.
10-10-2009, 01:12 PM
mduncan62

Then what do you do after you find it?
10-10-2009, 05:04 PM
Fishtaco

Tune your radio to Rush Limbaugh and hope the static goes away?

Dunno if that will work... someone once told me not to spit into the wind, or pull on Superman's cape. Same theory I think.
10-11-2009, 09:00 AM
J White

Quote:

Originally Posted by mduncan62

Then what do you do after you find it?

I'd say turn off things one by one until you isolate exactly which piece of
equipment is the guilty party, then you could try to seperate all it's wiring
from other stuff you don't want it bleeding over on. Other side of the boat,
or even a few extra inches betweent the wires might make a big difference.

On a side note, the Vexilar Edge III that came on my boat absolutely
drives an FM radio wild. Clicking and popping. But, it's probably as good
a sonar as I've ever used even though handicapped by an old school color screen...
It's not easy to see in sun, not real high pixel count either, but as far as
showing whats down there without clutter, it's top notch :confused:
10-11-2009, 09:32 AM
Cane Pole

Quote:

Originally Posted by J White

I'd say turn off things one by one until you isolate exactly which piece of
equipment is the guilty party, then you could try to seperate all it's wiring
from other stuff you don't want it bleeding over on. Other side of the boat,
or even a few extra inches betweent the wires might make a big difference.

That is the way to do it.

Sometimes you have combination noise sources where several operating equipment combine to creates a noise. That when it gets hard. Ask any dealer.:D
10-11-2009, 09:40 AM
Cane Pole

What creates a lot of the noise trouble is the way the boats are wired from the factory. Access is mostly thru cable troughs. Parallel lines causes the problem of induction.

We create a lot of our own problems by tying wires neatly in bundles. I am guilty.
10-11-2009, 09:44 AM
Cane Pole

Quote:

Originally Posted by IBNFSHN

I use to know that. Completely forgot how handy an old transitor radio was.

Me too. My neighbor (a retired ag teacher) was troubleshooting his truck radio the other day.

Thought I would mention this as it seems to be a lost art.

The AM radio works best when dialed between stations. No Limbos.
10-11-2009, 12:09 PM
CatFan

This is a great tool for finding shorts in most any kind of wiring. When you move the wire that is shorting, sparks from the short generate RF which the radio sees as static. Very useful for trailer shorts.
10-11-2009, 01:19 PM
Crappie Reaper

What ya posed ta do wif it if ya do find static??
10-11-2009, 01:36 PM
mduncan62

Is there any type of shielding that would take care of it?
10-11-2009, 01:46 PM
gopher

once you find which wire is giving you the static you can put a rfi filter on that wire
10-11-2009, 08:13 PM
Joby @ Humminbird

If you are having Interference on a Humminbird Fishfinder you can contact our customer service group and give them your setup and we will send you out a kit that will take care of the interference. Humminbird Customer Number is 800-633-1468.
10-11-2009, 10:31 PM
Hanr3

There are specific items on your boat that generate static noise and transmits through the wires to the rest of your circuits. Electronics are the most sensative, like your depth finder.

Your trolling motor(s) and boat motor(s) both generate noise and they both need to be wired directly to yhe battery and not part of any other circuit.

Also make sure your wires dont run near the motors, they create a magnetic field that will penetrate teh wire sheath and introduce noise to your clean circuit. Clean being connected directly to the battery.

If oyu have a Marine Radio, equvilent to a CB radio, you must make sure this is also on clean power and specifically away from static noise sources. They dont handle the noise well and it severly affects the distance you can transmit and receive.

If oyu can, seperate the trolling motor wires away from teh rest of your wires. Use the automotive wiring looms. Its slit down teh side from one end to the other and will slide over your wires where they lay.

Another source of noise is your pumps, livewell, airator, bilge, seperate clena circuits from yoru sensative electronics.

Most poeple have one power wire running from the battery to a terminal block and everything is connected to teh terminal block. Taht block just connected all your circuits and non of them are getting clean power. Put your trolling motor on its own circuits back to teh batteries. Put your dc motors, pumps, on there own circuit and back to the battery or common terminal block to those circuits. Put your sensative electronics on thier own circuits and back to one clean terminal block, back to the battery. Same with the grounds/negative side of things.

That will filter out 99% of your noise problems. If you still have interference, use a filter at each device you need to protect.
10-12-2009, 07:07 AM
Crappie Reaper

TM is on it's own battery with nothing else connected. All other electrical is rigged to other battery. Boat motor directly to Battery. Then two other sets of wires, one for port and the other for starboard. I no need no stinking circuit board. Each set fused at the battery, then spliced with junctions. Only noise I get is when I fart. (Tell the kids it's a fish call) Thanks for the info, I'll know what to look for should I have trouble.
10-13-2009, 03:07 PM
Cane Pole

If your TM is on a separate battery and your TM is bolted to an aluminum boat, you still have a possible ground loop which can induce noise. MOAO

Prove me wrong anyone?
10-13-2009, 06:55 PM
Crappie Reaper

Quote:

Originally Posted by Cane Pole

If your TM is on a separate battery and your TM is bolted to an aluminum boat, you still have a possible ground loop which can induce noise. MOAO

Prove me wrong anyone?

Nylon bolts, TM base insulated
10-13-2009, 08:32 PM
Redman

From a old old Ham radio Op. Ground it and shield it. If that doesn't work then add a RFI fillter. And yes those old transistor AM radios are a great tool. Even take one with me Crappie fishing just to past the time and keep track of the weather when I am out on the river.

Redman
10-13-2009, 09:06 PM
Cane Pole

Quote:

Originally Posted by Crappie Reaper

Nylon bolts, TM base insulated

Good boy.:)
10-13-2009, 09:42 PM
Cane Pole

If you not bs me and you are having EMI problems after what you have already done, try installing a ferrite bead near as possible to the sonar head unit. You can git 'em (ferrite) at radio shack.

http://leadertechinc.com/ferrishield...Fdpb2godETPp0Q
10-14-2009, 09:11 AM
Cane Pole

I don't know if Humminbird sells their big "donut" filter separate for other applications. But, it works good to reduce the TM noise. i would guess that it is a toroidal ferrite coil wound for ground and power leads.
10-14-2009, 05:45 PM
Cane Pole

Last resort. Run a separate ground wire from the TM case to the TM battery negative. Try this, even with separate battery for electronics. May be big EMI via metal boat. Metal boat ain't nothing but a big antenna. I hate to do this but it is sometimes necessary.