I have a Lowrance LMS-522c on the driver's console of my boat.  The boat came with the typical child's toy Lowrance model (the model number escapes me) that ships with Tracker boats and I moved that one to the front with the transducer mounted on the trolling motor.  When my budget allowed, I replaced that piece of junk with a Lowrance X125.

Both of these units work great and I'm very pleased with them especially the value I got for my money.  My problem with them is this:  When I operate them both at the same time, they interfere with one another.  I get vertical lines on both units.  The display is still readable but it's far from desirable.  I'm fairly certain this is caused because both units transmit at 200kHz. 

The workaround I have been using is turning the rear unit off when I'm on the trolling motor.  The problem with that though is if I want to save a GPS waypoint, I have to wait for the unit to go through it's start up routine and I'm not on the spot I want to place the waypoint at anymore.  My buddy also complains about not knowing the depth and water temp but he's a whiner  ;D

Is there any solution to this problem short of buying another sonar with a different transmit frequency for the bow?  I really don't want to have to resort to that.  Any help is appreciated.

You will have that problem regardless of the sonar manufacturer/model you have. The vertical bars you see are the two signal cones (radiating from two transducers) bouncing against one another. I've set up 2 deep V's with dual sonars and both have to have one shut off, in order to read the other.

And in reality, do you really the need to run two at a time anyway. You can only look at one! I do believe there is a device, whereby dual sonars can operate, but that usually involves "networking" the two units. More wires and connections; that allow two monitors, using one transducer. Call Lowrance for details.

BTW, I've had both the X-135 and the X-125. Outstanding sonar units. Trying to learn an HSD-5 now!

The only way you can prevent the two transducers for interfering with each other is to fish shallow enough to keep the cones from overlapping each other.

The connection used for sharing a single transducer is the Network. You can check all the parts needed on the Lowrance site.

I'm pretty sure your X125 won't hook up with the ethernet which would allow xducer sharing and eliminate all the cross talk.

In order to nullify the interference and keep the unit turned on for wpt use you can go into the menu and stop the chart.  That will only kill the 522's ability to send out pings and your X125 will function like it was the only unit in the boat.  When you pull up the tm just start the chart again and go.  It is a lot faster than having to reacquire the sats.

From the sonar page press MENU go to STOP CHART press enter.  To get off press STOP CHART again and press exit.

I'm pretty sure your X125 won't hook up with the ethernet which would allow xducer sharing and eliminate all the cross talk.

In order to nullify the interference and keep the unit turned on for wpt use you can go into the menu and stop the chart. That will only kill the 522's ability to send out pings and your X125 will function like it was the only unit in the boat. When you pull up the tm just start the chart again and go. It is a lot faster than having to reacquire the sats.

From the sonar page press MENU go to STOP CHART press enter. To get off press STOP CHART again and press exit.

+1 Very good advice.  The ethernet is required to share a single ducer and the X125 is not compatible.  As Jig Man said, just select the stop chart feature on your 522.

Upgrading the front unit with an HDS model would enable ducer sharing via ethernet, and allow folks in the back to see what you see up front while fishing.

Thanks for the replies guys.  I will definitely be using the Stop Chart function.  I can't see buying an HDS right now and the ethernet equipment right now.  I am saving up for a bigger motor!  I will keep the idea in mind.

I'm curious why the x47 (or whatever the junk unit that came with the boat was) didn't interfere with the 522.  I suppose it may have had a different frequency but I did some looking on both Lowrance and Humminbird's websites and 200kHz seems to be a pretty standard frequency for sonar units.

The X-47 is 200 khz.

I looked up the NMEA 2000 Networking info (pre ethernet) and the X-125 is not compatable with it either. That didn't happen until the later issue X-135.

Strange...I have a 522c and a LMS480 side by side on the console. Transducers are mounted outside the boat at the back of the transom just to each side of the lower unit. I have a X135 up front working off the TM. Never had a problem with any interference.

I am running the HST-WSBL wide angle transducers on all. They stay on unless I am working very shallow water, and that ain;'t very often.