Thread: RF Interference

ok, has anybody figured this rf interference out? I have a humminbird 858 di with a ton of interference..... banghead

RF/TM noise interference improvment (597ci HD DI)


Last week I was informed of RF/TM noise on screen shots of my new 597ci. Here's waht I was seeing at trolling speed .8-1.0....


After doing some research I rerouted the transducer wire away from the coiled power wire and installed a pair chokes on the TM power cord. Here was the result...(setting were 9 sensitivity, 9 contrast with surface clutter set to 1, noise filter set to high1).


Not quite what I wanted but I could live with it if neccessary. But I continued to reasearch the subject.
RF Chokes installed....

Today I twisted a 18 gauge wire around the transducer wire and spliced it into the negative wire on the sonar unit (tried the neg. wire on the TM power with no results) and anchored it to the clamp on the TM motor and covered the exposed wire with liquid tape. Here is the result...(sensitivity set to 12 (14 was clear as well), contrast 10, surface clutter 5, and noise filter off)....

Still needs some tweaking on sharpness and whatnot, but as can be seen there is very little RF/TM noise showing on the unit while the TM is running at trolling speeds. Need less to say I am very happy now.

The fix....

Cane Pole, so would using the rectangle snap-in chokes wrapping both power and ground wires work better or worse than just using the single wire long rectangle snap-in choke to wrap the red power wire?

Originally Posted by Superx10

Cane Pole, so would using the rectangle snap-in chokes wrapping both power and ground wires work better or worse than just using the single wire long rectangle snap-in choke to wrap the red power wire?

Both wires. I talked to Palomar engineer and he recommended 5 turns on a ferrite toroidal.
Call them. Tell them your issues, and they will recommend a possible solution. They know a lot more than I do about noise.

Palomar Engineers | Amateur Radio

Having some interference issues tried a RF choke with no help then grounded the 24 volt TM batteries Neg post only (per instruction on the sticky) to the starting battery with no help. Should I leave it grounded for any reason?
I did adjust the RF setting from the menu of the 597 and 798 I can’t remember what it was called but that did take care of most of my interference issues. I'm not sue what else to try. It mainly happens on the 597 when I engage the TM but only on start up.

Also I’ve seen some people put the choke on the TM power cord/plug……mine is on the power to the graph, which is correct or is there a correct answer? It’s just a magnet right?

Don't know much about the white stuff but I cured most of my RF inteference buy wrapping my TM wires around 2 RF chokes right at the TM plug. I used 2 chokes and wrapped the wire 2 times on each of them. I didn't have much luck adding the grounds but these issues for each unit are unique to different boats. You just have to keep trying to different things until you find something(s) that work for you.

Do the Lowrance Elite 5 DSI FF/Chartplotters have thesame problem with interference as the Humminbird DI units? I use a Minn Kota VariableSpeed TM.

Thanks,
FlyBye

Originally Posted by FlyBye

Do the Lowrance Elite 5 DSI FF/Chartplotters have thesame problem with interference as the Humminbird DI units? I use a Minn Kota VariableSpeed TM.

Thanks,
FlyBye

RF interference is often confused as a "DF problem"....

We always have to remember that interference is created somewhere else in the boat...the DF's today are just sensitive enough to pick this stray interference up...

There is no accurate way to predict if any certain DF unit will have interference issues...

Your boat setup...(the interference culprit)...may or may not create interference...

Rickie

Any thoughts as to why this interference happens on all speed settings except full?

When a trolling motor is at the full speed or WOT setting it is not using the Pulse Width Modulation (PWM) circuitry that it has to maximize the battery life. Therefore it is not generating the RF signal that is causing the interference.