Sonar issue

[JRinNE]

Helix 5 is mounted at the bow and I'm getting these random readings at an angle across the screen, only on sonar it does not show up on DI. Power is not supplied from the tm batteries. Transducer is mounted on the tm with the cable running down the shaft. Doesn't seem to matter if the tm is run in or not it just shows up. I've had the unit for 4 months now and this just started a couple weeks ago. Any ideas?

[yarcraft91]

There is a second sonar operating when you see this, I expect. Probably a second sonar with a transom mount transducer. If so, it's interference from the other sonar- I've seen this before on my boat.

[JRinNE]

I do have another helix in back with a transom mount, that was my thought but wasn't sure. Thanks for the reply. Were you able to correct it?

[yarcraft91]

Originally Posted by JRinNE

I do have another helix in back with a transom mount, that was my thought but wasn't sure. Thanks for the reply. Were you able to correct it?

There are two ways to correct it.
- Turn off one of the sonar units.
- Operate the sonar units at different frequencies (e.g., one at 50 KHz and the other at 200 KHz).

What's happening is both sonar units' transducers are sending pulses at the same frequency and pulses from both are bouncing back to both transducers. Your sonar sees two different signals at the right frequency that each look like "bottom" and plots it that way. The pulse repetition rates for the two sonars are very similar but not exactly the same, so one of the bottom returns appears to drift (up or down) while the other stays on true bottom.

[sfw1960]

HB units ping 200KHz all the time.

[yarcraft91]

Originally Posted by sfw1960

HB units ping 200KHz all the time.

Not when a unit is turned off.

[Kevin23]

Not necessarily the issue. I had two lowrances running on 200khz on the last boat without a single issue. I now have one on the current boat and i am seeing the exact same interference you are. I have not had the time to figure out the cause or play with the settings yet. I get the interference even with nothing else running, im going to have to run wires straight to the battery.. Dealer wired it to switch panel and i suspect that is the issue.


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[Shellback]

On an H/B, you should be able to push the power button once and a menu will come up. It should allow you to turn the sonar off. Swapping seats? just remember to turn the sonar off on the unit you aren't watching. If both units sonar is on, they will ping in 200. H/B gets their depth reading off of the 200. Doesn't matter if you have another frequency selected. Just a nature of the beast.

[JRinNE]

I think the reason I have the interference now and not before is I'm fishing deeper water. Kind of stinks I can't have both going when there are two of us in the boat. It would be nice if Hummingbird would do something for those of us that can't afford the higher priced gear to network and alleviate this issue. Does this issue occur with lowrance and garmin also or are you able to change the ping on those?

It's really a minor inconvenience but it drives me nuts!

[Shellback]

Originally Posted by JRinNE

I think the reason I have the interference now and not before is I'm fishing deeper water. Kind of stinks I can't have both going when there are two of us in the boat. It would be nice if Hummingbird would do something for those of us that can't afford the higher priced gear to network and alleviate this issue. Does this issue occur with lowrance and garmin also or are you able to change the ping on those?

It's really a minor inconvenience but it drives me nuts!

I have Garmin and Lowrance units. Both allow me to set a specific frequency to prevent interference. I had terrible interference running my Lowrance LMS 522 off my Motorguide transducer. Put a Garmin up front and have no interference. Have a Garmin 70DV and a Lowrance Elite 7Ti at the helm, and no problem there either.