Help With Interference after Upgrading

Hello All, the purpose of this post is to gather some ideas and advice about what may be happening in my situation. For the last year I have had the following:

Helix 7 DI G2N (console) (DI transducer on transom) (AS GPS on stern)
Helix 9 Mega SI G2N (console) (Mega SI transducer on transom)
Helix 10 Mega SI G2n (bow) (Mega SI transducer on Ultrex) (AS GPS on bow)
Ultrex version of the 360
Ultrex 112lb 36 volt link
All hooked to ethernet switch

***With this set up I never noticed any interference no matter what transducer I had allocated to whatever unit.



Here is the problem:

I purchased a new Helix 12 G3N Mega+ SI and installed it yesterday. All I did was change the transducer to the new one from the Helix 9 on the transom, and placed the 12 head unit where the 9 was (had to change the mount obviously). Basically just swapped the new 12 in place of the 9.

Was out at the lake today and with all (3) graphs on the 360 was so "wagon wheeled" with interference that is was virtually unusable. If I shut off both graphs (the 12 and 7 at the console) it would get much better but still a little interference. After that I tried it with just the 7 on (bad interference) and was the same with just the 12 on (bad interference). I also had some bad interference on the 12 when using side imaging and the Pro XS250 running, kind of a random strafing effect that was a different color and would come and go. All the electronics are fed from my cranking battery and the Ultrex is on a dedicated 3 bank.

Seems really weird that by just swapping the one graph out all these problems arise. Is it possible that:

1. The ferrite ring on the power cord for the gen3 is different (currently using the one from the 9)?

2. Something is internally wrong with the new 12 or new mega+ transcducer?

3. Something in a setting (noise filter)?

4. The (3) transducers I am using don't wanna play nice together (lol)?


Anyway, sorry for the long post but I really need some ideas on what to try. I will check the ground fuse in the ultrex tomorrow but I doubt its blown.

Any and all ideas, comments, tricks, solutions, etc. will be much appreciated!

Post this on the Humminbird page, likely to get more help there.

Thank you for responding. I did.

What cranking battery are you running? A lot of issues have been caused by batteries that do not have the proper amps needed for 3 graphs and a 250 proxs.

Brand new Exide 31AGM. Most powerful I could find locally (Academy). I have been thinking about ordering an Odyssey though.

And/or adding a 5th battery.

Never had this problem running the other 3, although I know that new mega plus 12 draws a little more juice than the 9.