Topic: 797cSI interference from MK MaxxPro 101 trolling motor

[Jasta]

I continue to have interference problems on my 797csi from my MK 101 trolling motor (60" shaft with Built in transducer).  I've done everything in print to solve the problem yet I still have this interference problem

1  Installed ferrulite ring kit
2  Dedicated & isolated hot wire
3  Reinstalled transducer wire away from shaft and cables
4. Checked fuse in TM head
5. Changed Transducers 3 times (Stock, HD, HD replacement with Nickle(?) shielding)
6. Insulated transducer cable in plastic tubing from Trans to point where cable leaves the shaft.

Each step has made small improvements.  But I find that the only way to really use the SI function on the Bow is to turn off the sonar on my 997CSI (console) and drift or be anchored with my MK Talon.

I have a 797CSI Interlinked to my 997CSI.  I have a Weathersense connected to the interlink and I use one 50 ch GPS puck for both units which is connected to my 997CSI.  I also use a Minn Kota 4 bank battery charger

I'm die-hard Johnson Fishing but I'm  Frustrated.  See attached doc for pictures

[Humminbird_Greg]

Where are the ferrite rings installed?
Did you try the filtered power cable yet (PC-11)?
Did you try the trolling motor Trolling Motor Choke (TMC-1) yet?

I would call the Humminbird Customer Resource folks back and see what they recommend you try next.

[Jasta]

I was one of the earliest customers to receive the chokes and ferrulite kits.  have them on all the units.  The last correspondence with HB was that they wanted me to run a ground wire from the TM skeg, up the shaft and all the way to the negative post of my battery?   I haven't tried the PC11 cord.  The package says its for the 798 and the 998. will it work on the 797? 

[Kidott429]

Your post didn't say, but which battery powers the hummingbird.  I have a terrova trolling motor and the installation instructions said due to the pulsing of the current to the trolling motor for speed control, sonar units couldn't be on the trolling motor battery.  So I had to pull new wire and hook both sonar units to my cranking battery, and I haven't had any noise issues.

[Jasta]

It's on the cranking battery.  The 101 is a 36 volt motor

[Whistler]

Hi Jasta,

I don't have the exact same setup as you but I was able to completely eliminate my noise problems by connecting a wire from the negative on my SI unit to my trolling motor shaft.  Doing this essentially grounded the trolling motor housing which was essentially acting as a RF transmitting antenna whose signal was being picked up as noise on the SI.

I'm not sure if the Minn Kota shaft is metal or composite. If its metal you can connect the ground wire to it. If not then try connecting the ground wire to the TM skeg as suggested by support.

Good luck!

[Jasta]

That is what they suggested.  Now that i've actually heard that someone else has been sucessful with it, I'll give it a try.  Thanks for the reply.  I Love Johnson Fishing (MK/HB) products and their support staff, but it really frustrates me as a customer when I spend thousands of $ on their products and have to retrofit them to handle situations that should have been caught in the QC process prior to launching the products! 

[ITGEEK]

If I understand correctly, you have 4, 12-volt batteries?
3 power your 36 volt and the one that is not hooked in with the 36 volt is
the cranking battery.
And, your sonar is hooked to the cranking battery?

Also, I'm not sure you are having interference from the trolling motor, or from the
sonar transducer you are using on that trolling motor.

As has been posted recently, you can't use two sonars at the same time with the same
frequency (unless your have a really long boat).  Regardless if you are using SI or not,  both of your sonar units will be pinging for depth at the same frequency (200khz).

[Jasta]

You are correct with my setup.  I know that my interference is coming from the Trolling motor because I turn off the other unit.  I only have the interference when I engage the trolling motor.  It the interference comes in the form of a "Greying" effect on the image.  See the attached images.

[ITGEEK]

I don't have any experience at all with transducers that are built into
trolling motors.
But, it seems logical, that with the transducer being so close to the
trolling motor wiring, that interference/vibration would be a constant problem.
Maybe it's better to attach the transducer to the outside of the
trolling motor shaft with brackets, like so many people do.
Then route the sonar wires away from the trolling motor wires.

Although, I'm not sure this is an option for you.

[Humminbird_Greg]

I was one of the earliest customers to receive the chokes and ferrulite kits.  have them on all the units.  The last correspondence with HB was that they wanted me to run a ground wire from the TM skeg, up the shaft and all the way to the negative post of my battery?   I haven't tried the PC11 cord.  The package says its for the 798 and the 998. will it work on the 797?

Yes, the PC-11 can be used with the 797c2 units.

[Jasta]

So I purchased a 998csi, sold my 797csi,  moved my 997csi to the bow and installed my new 998csi on the console.

I started with the same shielded HDSI transducer that I had used with my 797 mounted on the TM, (replaced by HB in2007) and still had interference.

I hooked up the new HDSI transducer that came with my 998 and voila, no interference.

I then fully installed the new TD exactly like the old one and I only have very slight interference spike when I engage the TM.  I tested it at multiple speeds with no issues.  It makes me wonder if there are inconsistencies with the TRansducer production.  Granted, all of this testinlg was in my garage.  We'll see what happens when I can get on the water.