lx-3 depth?

[sweth]

Hey I am looking at probably getting an lx-3 but am concerned with having only the 20 degree cone as I may be fishing in upwards of 120 ft of water at times. Is this going to give me problems? What is the max depth the 20 degree cone works good to before it is just to spread out?

[IceholeFisherman]

This is from the Marcum LX3TC manual:
Cone Angle Coverage - The cone angle of all LX-3tc transducers is 20 degrees. A general rule of thumb is that the coverage (distance across the signal beam) is 3.5 feet per 10 foot of depth. In 10 feet of water, the coverage is 3.5 feet; at a 20-foot depth, the signal beam is 7.0 feet across; and in 30 feet its 10.5 feet of coverage.
14


This info was copied from the Vexilar website.

This chart shows the difference in area of coverage between the 9, 12 and the 19 degree transducers.  It is meant to give you a rough idea of what the diameter of the circle, in feet, on the bottom you are seeing at a specific depth.  You must keep in mind that these are transducer specifications and, unless you have your gain set at the maximum level, you will actually be looking at a smaller area.  This brings up another interesting point.  Your gain control acts much like a variable cone angle control.  The drawback is that when you turn your gain up high everything in the middle of the cone gets blown up to the point where you can't see what's on the edge anyway.

Area of Coverage
DEPTH    9°    12°    19°
--------------------------    
10    1.6    2.2    3.4
20    3.2    4.3    6.7
30    4.7    6.3    10.0
40    6.3    8.4    13.4
50    7.9    10.6    16.7
60    9.4    12.6    20.0
70    11.0    14.7    23.4
80    12.6    16.8    26.8
90    14.2    20.0    30.1
100    15.7    21.0    33.5
120    18.9    25.2    40.2
150    23.6    31.5    50.2

[sweth]

Thanks that helps. From looking at that I would feel that the lx-3 is probably good to 60 maybe 80 feet but after that you would start greatly benefiting from the narrower cone. Well I guess I will hope I can swing the lx-5. Anyone else with deep water lx-3 experience?

[IceholeFisherman]

The LX5 with a 8/20 deg cone angle would be better at that depth. Save your pennies, have a garage sale, turn the furnace down to 60, sell the wife's cat to a cosmetic testing lab, steal the kids lunch money (maybe the lunch money is little over the edge), but do what you got to do to get one. You wont regret it!

[icetechy]

sweth - Your gonna be amazed when you hit that NBT button on your new LX-5!

[baldy]

IceholeFisherman,
I thought the gain only had to do with the sensitivity (how much power you use / junk you detect).  Should have the same cone angle regardless.  Or am I wrong?
Nick

[icetechy]

The gain does have to deal with the sensitivity. The deeper the water you fish the more gain you will need, in the process you will also be receiving more feedback and also feed back from other sonars in your area.  The LX-3 does pretty good job of dialing down the interference but the LX-5 is a beast when it comes to shutting it out.  With the LX-5, it is a must have if your fishing deep or heavy weeds. Remember your concentrating that power in a smaller area 8 deg (NBT)., which allows you to see  in spectacular detail basically a bit less than 1/2 of what you would see with the 20 degree.  It will also help with interference if your out there fishing with your buddies in close quarters.  I have friends that run LX-3's and what's nice about having the 5's mixed in with the 3's is the 5's can go to to the NBT and reduce the interference on the 3's so you can fish close to your buddies.  Granted bottom type also plays in this especially if your fishing rock.  If your out on the ice predominantly by yourself you probably would not need the NBT feature.  Why not have the versatility for a few dollars more.  Franks loves his LX-3 and when the TC came out before the upgrade he bought the LX-3TC and right after that he wished he had purchased the 5.  Frank ended up selling the LX-3tC and bought the 5 for it's versatility.  If you are having a tough time affording the LX-5 Pete at fishingprostore an authorized MarCum outlet did have some refurbed LX-5's at a great price and these units are in like new condition with a warranty, can't beat that also they have refurbed LX-3's at an incredible price there as well.

[baldy]

Right.  If you fish deep, you need more power/sensitivity to pick up a jig or get a good bottome reading.  That's what the gain does for you.  It allows you the option to adjust the sensitivity for your fishing conditions.  It doesn't mess with the cone angle.
I bought the LX3TC because of the price.  I just bought a new one for $315.  My price limit was $300 (actually was looking for LX2) but couldn't pass this deal up.  I generally fish in 60ft or less so 20 degree cone is fine.  With a 20 degree cone in 60ft of water that means the fish on the bottom that show up, will be within 10ft of my jig (~20 ft diameter with a jig in the center of circle).  Most of the time I'll actually be in 30 ft or less so even closer.
Nick

[IceholeFisherman]

IceholeFisherman,
I thought the gain only had to do with the sensitivity (how much power you use / junk you detect).  Should have the same cone angle regardless.  Or am I wrong?
Nick

That info that I posted came directly from the Vexilar website. Their research shows your flasher will "hear" less from the fringes of your cone angle when you turn the gain down. Gain does nothing to limit or intensify your power levels. When you turn your gain down, your unit will still transmit at the same power level. Its not how much power you transmit(that remains constant), its how much power you receive back to the unit.  Your gain works like a hearing aid. You turn it down so as not to hear a lot of nagging interference (i.e. the wife) even though the  transmitting volume level remains the same. JUST KIDDING LADIES. Or am I?

[heshootshescores]

When fishing lakers deep I combine the nbt with the sfl on the lx5. Real nice read out......I swear I can see fish movement on the outside of the cone.