Interference Question

[jphersh22]

I've read a lot of comments on posts about this but they've been conflicting and I'm a little confused and I'm about a day away from buying a FL18 instead of a LX3 becasue I fish with my dad who has a FL8. If I've got this right I'm thinking he and I will have less interference with same brand flashers than we'd have if I got a Marcum, but again I'm not sure. I know the Marcum has better interfernce rejection but I don't want to make my dad's FL8 go nuts. Another FL18 bonus is our local Gander Mountain has the FL18 $40 off right now.

[Matt Johnson]

Your dad is going to have interference either way. An FL-8 and FL-18 will cause interference with each other, but I believe the FL-8 will see less interference with the FL-18 than with the LX-3. The only 2-sonar system that doesn't see a lot interference is going to be a MarCum vs. MarCum. Two Vexilars will have interference, as will a Vexilar and MarCum. When using a Vexilar and MarCum you will notice a lot less interference when viewing the MarCum then you will viewing the Vexilar.

I see what you are asking, and if you are looking at giving your dad the least amount of interference, then you are going to want to go with the less powerful unit, and that would be the FL-18. While if you got an LX-3 your screen will be free from interference, but your dad would suffer.

I've fished two Vexilars right next to each other in the past and although there is still interference, you'll have less interference than with a MarCum in the mix.

The best possible solution (from what I'm experienced) for both people is to run two LX-3's side by side. Virtually no interference and everything is crisp and clear.

I know the FL-18 has increased their interference rejection and they are better than they used to be, but I still see better results with a MarCum.

Good Fishin,

Matt Johnson

[Ed Carlson]

If your Dads sonar unit is a FL-8 SLT he will be able to change the processor frequency and tune out any interference from your FL-18. With your FL-18 you will be able to change the frequency with your IR and that may eliminate his interference even if his unit it is an older FL-8. It somewhat depends on what transducers you both are using.

If you have a duel beam and run your unit on a narrow beam, it would limit the interference to other close proximity Vexilar units. If you eliminate overlap of the two compatible transducer signals, it will eliminate the interference.

Power has less to do with interference then does the frequency used by the processor to interpret the returning sonar signal. The purpose of the Vexilar IR feature is to shift the frequency a tad one way or another so like returning sonar frequencies do not conflict. In the best of all worlds, both units would have an IR feature allowing for more frequency variables.

It is very rare that a FL-18 can not phase shift enough to eliminate all or most of any sonar interference. I have used FL-8 SLT's next to FL-18's many a time, and near FL-8's. If I get interference that is blasting another unit I spread out a bit and it solves itself.

[jphersh22]

Maybe this is a dumb question and it will be clear when I get the Vexilar, but how do I change the frequency like you're saying?

[Matt Johnson]

There is a button on the flasher that reads "IR". You can push that button to change the setting. There are a few different settings. On some units you can also push the entire gain knob and it will reset the settings.

Ed is right, you can eliminate quite a bit of the interference if you mess around with it for awhile, but you will still have some interference regardless. After using your flasher for a while your eyes will get used to it and you will develop a sixth sense

Good Fishin,

Matt Johnson

[Pete Riola]

The FL8 will have interference with most any unit within it's cone. That unit could be another FL8 or an 18 or an LX3. The 18 and the LX3 work pretty well next to each other with the LX3 having the least amount of interference or none at all. The FL8 is a solid unit but old as far as technology is concerned. Bottom content is also a concern... if you fish a lot of rock or Canadian Shield lakes you have more return interference this is because the sonar bounces off the hard bottom.... if you fish more soft bottom like weeds or mud you have less interference. The LX3 is a product of the USA and it is engineered to have better target separation and better interference rejection than competing units. In any case you are bound to catch more fish by owning a sonar so you've made a good decision to buy one. Based on what you've learned which unit do you think ID's targets better? That may be the key question when spending your hard earned money on a sonar for your hobby.

[aquafang]

I fish within 2 to 3 feet of my buddy in either of our two man shacks. I have an older FL8 and he has the LX3. I see very little interference. Nothing that has ever confused or cost me to see fish or catch fish.

[Gissert]

I fished quite a bit in my protable with an older FL8 and a FL18 last winter. Interferance was not much of a problem. The FL18 had the 9/19 degree transducer, and I was able to cancel out the interferance most of the time. This was over a relatively flat bottom areas.

When fishing on steep breaks or large rocks, that is another story. I have had other units several yards away, and the interferance was a nightmare. The geometry of the signal bouncing off the upper portions of the break at an angle would cause problems for the deeper units. Under these situations, you might not be able to eliminate the interferance until you move far enough away from the other unit(s).

[marine_man]

I've fished in a house with two guys that were running FL-8's, and one guy running a LX-3. While it took some doing, it was possible to tune out the interference enough to be fishable. Yes, there was some blinking / interfernce high up on the water column, but now here near where we were fishing (near the bottom.

If we could do it with two fl-8's and a lx-3 I wouldn't imagine it'd be difficult to do it with one fl-8 and a lx-3.