Topic: Trolling Motor Noise

[George]

I was out this weekend using my 1197c for the 4th time since receiving it. 

The Trolling Motor Transducer totally disrupts the screen with noise and the transom transducer is marginally better when running the Trolling motor.  This does not make sense to me, I carefully routed the transom's transducer wire away from all electrical wires.  the wire goes across the back (outside) of the transom to the port side and is the only wire going up the port side.  The only place the wire comes close to any wires is where the two transducer wires come together and then where everything connects at the 1197c unit.  When running the 25 Hp Tothatsu outboard there is no noticeable electrical interference.  The trolling motor is connected to its own battery in the bow, the TM transducer goes up the shaft and goes down the portside and does not come in contact with the TM's electrical wires.  I think that I have done everything possible to minimize/eliminate any electrical interference. 

If anyone have suggestions I would appreciate your thoughts.  I am in contact with Humminbird, but would like to resolve the issue by removing the interference as much as possible before making HB's changes.

System Set Up
1.   Trolling Motor – Motorguide
a.   Freshwater Tour Series Digital Bow Mount
b.   54 lb thrust
c.   no universal sonar

2.   Humminbird Unit
a.   1197c NVB SI Model # 407160-1V
 
3.   Humminbird Transducer
a.   2 Transducers
i.   Stern Mount - Model # XHS-9-HDSI-180-T
ii.   Bow Mount – Model # XTM-9-HDSI-180-T

4.   Humminbird Switch
a.   TS2 W Double Transducer Switch
b.   No y cable

5.   Humminbird – Accessories
a.   TS W Temperature Speed Sensor
b.   No other accessories
i.   No interlinks
ii.   No System Links

[RGecy]

HB has release a ferrite core that comes on the new power cords to help reduce some of the noise.  There have also been some recommendations on grounding the trolling motor better.  I believe I read where someone attached a ground from the battery straight to the foot.

Do you have more than one battery?  If the HB unit and the Trolling Motor are on the same one, try moving the HB over to the other battery.

Rgecy

[George]

Yes I have two batteries, I added the second one to the bow of the boat which powers only the trolling motor. 

As stated above, the Transducers wires are routed on the port side away from everything the only place the transducer wires (fore and aft) come in contact with electrical wire is at the unit's electrical port.

I am also thinking about covering the transducer's wires with copper foil at the connecting point around each of the wires at the unit to see if it will act as a faraday cage and try eliminate the noise.

I was wondering if the TM motor was actually causing the noise where the transducer is actually connected with a hose clamp, any thoughts?  It appears that the SI transducers are much more sensitive then the normal transducers.

[kosmo]

just wondering.......... what would happen if a person rapped Aluminum Foil around transducer cable.would this help rf noise. or make no differance or could this damage the unit or transducer ??

[RGecy]

It would not damage the transducer.  Weather or not it would keep out the RF is worth a try.  I imaging there is a braided mesh that could be bought that would do the trick.  But remember, it should be grounded also to be effective.

Robert

[BamaTriton]

If anyone have suggestions I would appreciate your thoughts.  I am in contact with Humminbird, but would like to resolve the issue by removing the interference as much as possible before making HB's changes.

Make sure your 1197c SI software is up-to-date. In the menu click on the "Sonar" tab and scroll down to "Noise Filter" and try each setting. OFF > LOW > MEDIUM > HIGH 1 > HIGH 2 > HIGH 3, you must exit out of the menu each time for your change to take effect.

Your RF interference is from the MG trolling motor's motor. If you run it in high you don't have near as much interference or none at all right? It's when you start lowering the speed is when you get it? Think of it like this, If running in high the motor is using all the current to run the motor, when running in a lower speed it uses less current to turn the motor and therefor the unused current is sent into the air like a radio broadcast and all your SI's transducers and cabling is acting like an antenna picking it up. To reduce this your going to have to install a ferrite choke on the TM's power cable as close as possible to the motor, just before the foot controller or in the head (top) of the trolling motor. I found the head to be better but works in either place.

Humminbird will send you out a interference kit and in this kit will be a choke for the TM.

Good Luck!

[pebe]

Any new Informations to solve this Problem ?

The Interference might be a high frequency noise coming from the trolling Motors Electric which pulses the Power to the Motor.
Using two batteries can help, but only if they are not both connected to the boats hull.
even if the (-) from both batteries is grounded in the hull the noise is coming over this connection.

And yes, if running on full speed the noise is lower, running on slow speed the noise is higher.

Anyone solved this problem, for example with ferrit rings on the Power Cable ?

[sonar2000]

Often overlooked is the grounding of any unit. A lot of attention to the positive cable with little to the ground.   One concern with ground is using a metal frame to return as compared to a wire. I prefer a return wire over the frame grouond.  Also the ground wire size, particularly, if shared with other electronical units, should be large, as in number 12 size.  If the electrical   draw is significant, the a large ground wire is in order.  Chuck