John S - was that a 20-deg. cone for the 200 Khz only or the dual unit? The Lowrance tech said another important difference between the dual freq. 'ducer run in 200-Khz mode vs. the dedicated 200-Khz only is that the latter has a bigger cone...I think the dual unit may only have a 12-deg. cone...have to look it up. -Eric

Maybe this will help
From the lowrance website:

Most of the sonar units that we sell accessories for operate at 192 or 200 kHz (kilohertz). Some models use 50 kHz. A few are dual frequency capable, meaning they can use both 50 and 200 kHz transducers. Typically, high frequency (192 or 200 kHz) sonar units provide the best resolution and definition of structure and targets. They excel at showing minute details of the underwater world. 50 kHz units have much greater depth penetration capability, but show less definition. 50 kHz transducers also usually have a much wider cone angle than 192 or 200 kHz transducers.

You must match the transducer's frequency to the sonar unit. For example, a 192 kHz sonar unit requires a 192 kHz transducer.

Cone Angle
A transducer's cone angle determines its coverage area of the underwater world. The wider the cone angle, the greater the area that's covered. We offer a variety of 192 kHz transducers with either a wide (20°) or narrow (8°) cone angle. We also offer a variety of 200 kHz transducers with either a wide (20°) or narrow (12°) cone angle. The 50 kHz transducers come with a 35° cone angle. And the dual frequency transducers come with both a narrow (12°) 200 kHz and a 50 kHz cone angles.

Generally, use a wide cone angle for fishing shallow to medium depths. The narrow cone penetrates to deeper depths, but shows less fish and structure due to its narrow beam.

The depth capability of your sonar units depends on its transmitter power, receiver, sensitivity, frequency, transducer and transducer installation. Other things that effect depth capability are: water conditions and type, (all sonars will show deeper depth readings in fresh water than salt) and bottom conditions.

This explains a lot...but I'm still fairly confused. By going with the dual, you get a much narrower cone angle at high frequency(8 or 12 degrees vs. 20 with the single) ,so you get a smaller view of the bottom than with a single but with high definition. But at the lower frequency you have the wider angle cone and the ability to go deeper, but lose definition.
So if I want to see a wider view of the bottom with more definition in medium depths(say under 200ft), then I should choose a 192 or 200kHz wide-angle transducer.
Does that sound right?
My head hurts....too much info!

Erin

I'm lost now, I thought the 50 was narrower cone the way he talked about it, not wider ??????? Oh well, the popular choice for lakes like ours has been the 200 and this is verified by Lowrance techs.

Now as for other makes, I have no clue about cone width, etc.

Interesting discussion anyhow.

John S.

Not 100% positive which he was referring too, I assumed the single frequency as he was trying to make a statement not to get the dual. He did say in the conversation that the 200 single had a bigger cone.

Let me know what you find out?

John S.

Maybe he meant the 200 had a wider cone at the depths we fish. I give up.

John S.

--- --- --- --- --- --- --- --- ---

Replying to:

Not 100% positive which he was referring too, I assumed the single frequency as he was trying to make a statement not to get the dual. He did say in the conversation that the 200 single had a bigger cone.

Let me know what you find out?

John S.

...OK, that answers my question. The dual 200/50 unit I have has a 12-deg cone for the 200 Khz vs. the 20-deg cone for the single-freq. 200 KHz. So unless you'll be fishing deep in salt water, I'd highly recommend the single-freq. 200 KHz.

Its not confusing, just fisherman trying to do math! We never count, measure or weigh right, do we?

John and Eric I agree.For the lakes around New England the best freq. is 200 KHZ I bought a dual freq. finder because of lake ontario,the bottom doesn't change like Winni. and lakes in Maine but with the currents and fishing so deep I would lose my rigger weights when I passed 80 feet and the 50 KHZ freq.alows me to see them down as far as 140 feet.I was fishing 130 feet down this year at ontario to get 50 deg water so the 50 KHZ came in handy.I hope I don't come across like a know it all I'm just trying to pass along what I have been told and read.I'm still not sure what's what but all I know is that I could not fish with out a good finder.Thanks for all the feed back.

Erin

Erby...interesting; do you think its the chop on Ontario that causes you to lose the ball? I was able to see my balls (no pun intended) down over 100' in Moosehead.

Well I'm stuck with the dual ducer anyway and its been working pretty good. Lowrance recinded their earlier offer to replace the dual with a single 200 Khz...I guess the question for me is whether I buy and install the 200 Khz separately with a switch box...John S lucked out, they gave him the 200 Khz for free!

Joe G. -- you've got some good information to run with...good luck

Yes indeed. This is fantastic.Information galor. The difference between this site and others is that the information never stops. If someone gets a little out of line, Travis or Aj delete the nonsense and remind everyone what this site is all about. Thanks everyone again. I probably would have gone and bought something that a salesman said I needed and wouldn't have been too happy after-the-fact. Now I think I know exactly what I need.

Eric there is a lot of varables in Lake Ontario It all depends on the wind and under water currents on some days it takes 130 feet of cable to get to 100 feet.I know what you mean this is my first dual freq.unit also I have always had lowrance I do miss my paper graph I'm from the old school.I still don't think they can make a finder that showed the details so good as my paper graph.I still have it but it needs a stilest belt.Lowrance has had alot of problems with ther dual ducers tell them it's intermitent and they might send you a new one I know of at least 3or 4 people that fish ontario that had that problem.Just a thought.Thanks for talking catch you later.

Erin