Pub. 988-0151-171 www.lowrance.com
X125, X126DF, X135, X136DF
Fish-finding & Depth Sounding Sonars

Operation Instructions

Copyright 2003 Lowrance Electronics, Inc. All rights reserved. Lowrance is a registered trademark of Lowrance Electronics, Inc. Navionics is a registered trademark of Navionics, Inc.
Lowrance Electronics may find it necessary to change or end our policies, regulations and special offers at any time. We reserve the right to do so without notice. All features and specifications subject to change without notice. All screens in this manual are simulated. On the cover: X136DF shown. Other models covered in the manual are similar.
For free owner's manuals and other information, visit our web site:

www.lowrance.com

Lowrance Electronics Inc. 12000 E. Skelly Dr. Tulsa, OK USA 74128-2486

Table of Contents

Sec. 1: Read Me First!... 1 Capabilities and Specifications: X125, X126DF, X135, X136DF. 2 How Sonar Works... 3 How to Use this Manual: Typographical Conventions. 4 Sec. 2: Installation & Accessories.. 7 Preparations.... 7 Transducer Installation... 7 Recommended Tools and Supplies.. 8 Selecting a Transducer Location.. 8 How Low Should You Go?.. 9 Shoot-Thru-Hull vs. Transom Mounting.. 10 Transom Transducer Assembly and Mounting.. 10 Trolling Motor Bracket Installation (Single-Frequency only). 16 Transducer Orientation and Fish Arches.. 17 Shoot-Thru-Hull Preparation and Installation.. 17 Speed/Temperature Sensors.. 20 Sensor Chart... 21 Optional Speed Sensor Installation.. 22 Power Connections... 23 Mounting the Unit: Bracket, In-Dash or Portable.. 25 Face Cover... 29 Sec. 3: Basic Sonar Operation.. 31 Keyboard... 31 Power/Lights (Turn Unit On and Off).. 32 Menus... 32 Main Menu... 32 Sonar Menu.... 34 Pages... 35 Basic Sonar Quick Reference.. 38 Sonar Operations.. 39 Fish Symbols vs. Full Sonar Chart.. 41 Other Free Training Aids.. 42 Sec. 4: Sonar Options & Other Features.. 43 ASP (Advanced Signal Processing)... 43 Alarms.... 44 Depth Alarms... 44 Zone Alarm... 45 Fish Alarm... 46 Brightness... 46 Calibrate Speed... 46 Chart Speed... 47 Contrast.... 48 i
Depth Cursor... 48 Depth Range - Automatic... 48 Depth Range - Manual... 49 To Turn Auto Depth Range on Again:.. 49 Depth Range - Upper and Lower Limits.. 49 FasTrack.... 51 Fish I.D. (Fish Symbols & Depths)... 51 FishTrack... 53 FishReveal... 54 Frequency (Change Transducer Frequency).. 56 Grayline... 57 HyperScroll... 59 Noise Rejection... 59 Overlay Data... 59 To Change Displayed Data Font Size:.. 60 Ping Speed & HyperScroll.. 61 Pop-Up Help... 62 Reset Options... 63 Reset Water Distance... 63 Screen Contrast and Brightness.. 63 Sensitivity & Auto Sensitivity.. 64 To Turn Auto Sensitivity Back on:... 66 Set Keel Offset... 66 Set Language... 67 Software Version Information.. 67 Sonar Chart Mode... 68 Sonar Chart Display Options... 68 Full Sonar Chart... 69 Split Zoom Sonar Chart... 70 Split Frequency Sonar Chart (X126DF and X136DF only). 70 Digital Data/Chart... 71 Customizing the Digital Data/Chart Screen.. 72 Flashgraf... 73 Sonar Simulator... 73 Stop Chart... 74 Surface Clarity... 74 Transducer Type (X126DF and X136DF only). 75 Units of Measure... 76 Upper and Lower Limits.. 76 Zoom & Zoom Bar... 76 Zoom Pan... 77 Sec. 5: Sonar Troubleshooting... 79 Sec. 6: Supplemental Material... 85 ii
How this manual can get you out on the water, fast!
Welcome to the exciting world of digital sonar! We know you're anxious to begin finding fish, but we have a favor to ask. Before you grab your unit and begin installing it, please give us a moment or two to explain how our manual can help you get the best performance from your compact, wide-screen, fish finder. First, we want to thank you for buying a Lowrance sonar. Whether you're a first time user or a professional fisherman, you'll discover that your unit is easy to use, yet capable of handling demanding sonar tasks. You won't find another sonar unit with this much power and this many features for this price! Our goal for this book is to get you on the water fast, with a minimum of fuss. Like you, we'd rather spend more time boating or fishing and less time reading the manual! So, we designed our book so that you don't have to read the whole thing from front to back for the information you want. At the start (or end) of each segment, we'll tell you what content is coming up next. If it's a concept you're already familiar with, we'll show you how and where to skip ahead for the next important topic. We've also made it easy to look up any tips you may need from time to time. Here's how: The manual is organized into 6 sections. This first section is an introduction to the sonar unit. It tells you the basics you need to know before you can make the unit look below the surface to find some fish. Section 2 will help you install your unit and the transducer. We'll also tell you about some of the available accessories. Section 3 covers Basic Sonar Operation. It will show you how easy it is to run your sonar, right out of the box. This section features a one-page Sonar Quick Reference. (If you've already jumped ahead and figured out how to install the unit yourself, and you just can't wait any longer, turn to the Quick Reference on page 38 and head for the water with your sonar unit!) After you've gained some experience with your sonar, you'll want to check out Section 4, which discusses more advanced Sonar Options and Other Features. When you come to a sonar menu command on the unit's screen, you can look it up in the manual by skimming over the table of contents or index, just flipping through Section 3 or scanning through the sonar options in Section 4. 1

extreme care if mounting the transducer inside the hull, because once it is epoxied into position, the transducer usually cannot be removed. Remember, the transducer installation is the most critical part of a sonar installation. Recommended Tools and supplies If you prefer the option of routing the cable through the transom, you will need a 1" drill bit. A transom mount requires use of a high quality, marine grade above- or below-waterline caulking compound. The following installation types also call for these recommended tools and required supplies (supplies are not included):
Single-frequency transom installations
Tools include: two adjustable wrenches, drill, #29 (0.136") drill bit, flathead screwdriver. Supplies: none.
Dual-frequency transom installations
Tools: two adjustable wrenches, drill, #20 (0.161") drill bit, flat-head screwdriver. Supplies: four, 1" long, #12 stainless steel slotted wood screws.
Single-frequency trolling motor installations
Tools: two adjustable wrenches, flat-head screwdriver. Supplies: plastic cable ties.
Shoot-through hull installations
Tools: these will vary depending on your hull's composition. Consult your boat dealer or manufacturer. Supplies: 100 grit sandpaper, good quality epoxy adhesive. Selecting a Transducer Location 1. The transducer must be placed in a location that has a smooth flow of water at all times. If the transducer is to be mounted inside the hull, then the chosen location must be in the water at all times. If the transducer is not placed in a smooth flow of water, interference caused by bubbles and turbulence will show on the sonar's display in the form of random lines or dots whenever the boat is moving. NOTE: Some aluminum boats with strakes or ribs on the outside of the hull create large amounts of turbulence at high speed. These boats typically have large outboard motors capable of propelling the boat at speeds faster than 35 mph. Typically, a good location on aluminum boats is between the ribs closest to the engine. 2. The transducer should be installed with its face pointing straight down, if possible. 8
3. If the transducer is mounted on the transom, make sure it doesn't interfere with the trailer or hauling of the boat. Also, don't mount it closer than approximately one foot from the engine's lower unit. This will prevent cavitation (bubble) interference with propeller operation. 4. If possible, route the transducer cable away from other wiring on the boat. Electrical noise from engine wiring, bilge pumps and aerators can be displayed on the sonar's screen. Use caution when routing the transducer cable around these wires.

Align plastic ratchets in bracket.
B. Two-piece bracket: Locate the four plastic ratchets in the transducer's hardware package. Press two ratchets into the sides of the plastic bracket and two on either side of the transducer as shown in the following illustrations. Notice there are letters molded into each ratchet. Place the ratchets into the bracket with the letter "A" aligned with the alignment mark molded into the bracket. Place the ratchets onto the transducer with the letter "A" aligned with the 12 o'clock position on the transducer stem. These positions set the transducer's coarse angle adjustment for a 14 transom. Most outboard and stern-drive transoms have a 14 angle.
Alignment letters Alignment positions
Transducer Transducer bracket Insert and align ratchets.

Transducer bracket

Transducer

Ratchet

Add ratchets to bracket and transducer.
2. Aligning the transducer on the transom. A. One-piece bracket: Slide the transducer between the two ratchets. Temporarily slide the bolt though the transducer assembly and hold it against the transom. Looking at the transducer from the side, check to see if it will adjust so that its face is parallel to the ground. If it does, then the "A" position is correct for your hull. If the transducer's face isn't parallel with the ground, remove the transducer and ratchets from the bracket. Place the ratchets into the holes in the bracket with the letter "B" aligned with the dot stamped in the bracket. Reassemble the transducer and bracket and place them against the transom. Again, check to see if you can move the transducer so it's parallel with the ground. If you can, then go to step 3A. If it doesn't, repeat step 2A, but use a different alignment letter until you can place the transducer on the transom correctly.

Ratchets

Insert bolt and check transducer position on transom.
B. Two-piece bracket: Assemble the transducer and bracket as shown in the following figure. Temporarily slide the bolt though the transducer assembly but don't tighten the nut at this time. Hold the assembled transducer and bracket against the transom. Looking at the transducer from the side, check to see if it will adjust so that its face is parallel to the ground. If it does, then the "A" positions are correct for your hull. If the transducer's face isn't parallel with the ground, remove and disassemble the transducer and ratchets. Place the ratchets into the bracket holes with the letter "B" aligned with the bracket alignment mark. Place them on the transducer aligned with the 12 o'clock position on the transducer stem. Reassemble the transducer and bracket and place them against the transom. Again, check to see if you can move the transducer so it's parallel with the ground. If you can, then go to step 3B. If it doesn't, repeat step 2B, but use a different alignment letter until you can place the transducer on the transom correctly.

Transducer location (high speed) Transducer location (trolling speed)
Shoot-thru-hull transducer locations for high speed or trolling speed operation.
Shoot-thru-hull Installation 1. Make sure the area is clean, dry and free of oil or grease, then sand both the inside surface of the hull and the face of the transducer with 100 grit sandpaper. The surface of the hull must be flat so the entire transducer face is in contact with the hull prior to bonding.

Spread epoxy here

Sand this surface
Epoxy transducer to hull.
2. Follow the instructions on the epoxy package and mix it thoroughly. Do not mix it too fast, because it will cause bubbles to form in the epoxy. Apply a small amount on the face of the transducer as shown above, then spread a small amount onto the sanded area on the hull. 19
Place the transducer into the epoxy, twisting and turning it to force any air bubbles out from under the transducer face. The face of the transducer should be parallel with the hull, with a minimum amount of epoxy between the hull and transducer. After the epoxy dries, route the cable to the sonar unit.
Speed/Temperature Sensors
This unit accepts up to three temperature sensors which can monitor surface water, live well, bait well and virtually any other temperature. If you want to use more than one temperature sensor or a speed sensor, you must purchase the optional MY-4X adapter cable. You also need to be careful when purchasing the temperature sensors, because each temperature sensor has its own fixed electronic "address." The sensors are labeled "Water," "T-2" (or Temp-2) and "T-3" (or Temp-3). The first "Water" temperature sensor is built into the transducer. This is the sensor that measures surface water temperature. If you want two (or more) temperature readings from other locations, you'll need to use the proper sensors. For example, you can't use two additional T-3 sensors. The sensors that fit this unit are: TS-1X This sensor will over-ride the temperature sensor built into the transducer and over-ride the temperature sensor in a ST-TGY combination sensor. (This sensor is not recommended.) One sensor for "T-2" temperature display. One sensor for "T-3" temperature display. One speed sensor for "Speed" display. This combination sensor will provide speed and temperature readings, but the temperature reading will be displayed as the "Water" temperature because it will over-ride the temperature sensor in the transducer. (This sensor is not recommended.)

Power Connections

The unit works from a 12-volt battery system. For the best results, attach the power cable directly to the battery. You can attach the power cable to an accessory or power buss, however you may have problems with electrical interference. Therefore, it's safer to go ahead and attach the power cable directly to the battery. CAUTION: When using the unit in a saltwater environment, we strongly recommend that you shut off the power supply to the power cable when the unit is not in use. When the unit is turned off but still connected to a power supply, electrolysis can occur in the power cable plug. This may result in corrosion of the plug body along with the electrical contacts in the cable and the unit's power socket. In saltwater environments we recommend you connect the power cable to the auxiliary power switch included in most boat designs. If that results in electrical interference, or if such a switch is not available, we recommend connecting direct to the battery and installing an inline switch. This will let you shut off power to the power cable when the unit is not in use. When you are not using the unit, you should always shut off power to the power cable, especially when the power cable is disconnected from the unit. If possible, keep the power cable away from other boat wiring, especially the engine's wires. This will provide the best isolation from electrical noise. If the cable is not long enough, splice #18 gauge wire onto it. The power cable has two wires, red and black. Red is the positive 23
lead, black is negative or ground. Make sure to attach the in-line fuse holder to the red lead as close to the power source as possible. For example, if you have to extend the power cable to the battery or power buss, attach one end of the fuse holder directly to the battery or power buss. This will protect both the unit and the power cable in the event of a short. It uses a 3-amp fuse.
Optional power off switch for saltwater installations To unit
Black wire 12 volt battery Power connections for the sonar unit.

Red wire with 3 amp fuse

CAUTION: Do not use this product without a 3-amp fuse wired into the power cable! Failure to use a 3-amp fuse will void your warranty. This unit has reverse polarity protection. No damage will occur if the power wires are reversed. However, the unit will not work until the wires are attached correctly. An optional 8-foot, CA-4 external power cable with a cigarette lighter adapter is available from Lowrance.

Power socket

Sonar socket

Transducer Power wires

Sonar unit cable connections.
Mounting the Unit: Bracket, In-Dash or Portable
You can install the sonar unit on the top of a dash with the supplied gimbal bracket. It can also be installed in the dash or mounted on a portable power supply. If you use the supplied bracket, you may be interested in the optional R-A-M bracket mounting system. This converts the unit's gimbal bracket to a swivel mount, which can be used on the dash or overhead mounting positions. Installation instructions are supplied with the R-A-M mounting kits.

4. ARROW KEYS These keys are used to navigate through the menus, make menu selections, move the sonar chart cursor and enter data. 5. ENT (Enter) This key allows you to accept values or execute menu commands. 6. EXIT The Exit key lets you return to the previous screen, clear data or erase a menu. 7. ALARM The Alarm key is a quick shortcut to the sonar alarms menu. It allows you to choose which alarms to use and when. 8. ZOUT (Zoom Out) This key lets you zoom the screen out. This key returns you to a full sonar chart display, showing the entire water column from surface to bottom. 9. ZIN (Zoom In) This key lets you zoom the screen in. It enlarges fish signals, bottom detail and other sonar returns.

Power/lights on and off

To turn on the unit, press PWR. To change the backlight, press PWR again. The X125 and X126DF have two backlight levels to select from. The X135 and X136DF have three backlight levels. Repeatedly pressing PWR will cycle through the backlight settings, turn off the backlight, then turn it back on again. Turn off the unit by pressing and holding the PWR key for about 3 seconds.
Your sonar unit will work fine right out of the box with the factory default settings. You only need to learn a few basic functions to enhance your viewing. We'll discuss them briefly here, then talk about them and all the other commands in more detail in the next section, which begins on page 43. Your unit has three primary menus that control its operation. They are the Main Menu, the Sonar Menu and the Pages Menu. Main Menu The Main Menu contains some basic function commands and some setup option commands. You access the Main Menu by pressing MENU|MENU. You run a command by using the or to highlight the command and then pressing ENT. To clear the Main Menu screen and return to the Page display, press EXIT. (Remember, our text style for "MENU|MENU" means "press the Menu key twice." See a full explanation of our instruction text formatting on page 5, Instructions = Menu Sequences.) 32
Main Menu. Main Menu Commands
There are four "basic" Main Menu commands that you'll really want to read more about. They are: Screen command: changes the contrast or brightness of the display screen. Use this command to adjust how the screen looks under various lighting conditions. Sounds command: enables or disables the sounds for key strokes and alarms, controls the volume and sets the alarm style. If you don't like to hear a beep each time you press a key, you can turn this off, or select tunes or sound effects instead. The sounds are especially useful when used with the Fish I.D. fish symbol feature and fish alarm feature. Sonar Alarms command: turns alarms on or off and changes alarm thresholds. The fish alarm, used with Fish I.D., is the most popular use. It tells you when the sonar sees a fish. You can also set deep or shallow depth alarms and zone alarms. Popup Help command: turns the pop-up help boxes on or off. When you select a menu command, these information boxes appear to tell you what the command does or how to use the command. The default setting is on, which is really handy while you're learning. The remaining Main Menu commands are for more advanced functions, mostly setting various sonar options. (They're all detailed in Sec. 4.) Units of Measure command: selects the units of measure used for showing speed/distance, depth and temperature. Set Keel Offset command: calibrates the unit to show depth under the keel or actual depth from the surface. Calibrate Water Speed command: adjusts how a speed sensor measures water speed. 33

Other Free Training Aids The sonar options section discusses Fish I.D., fish alarms and other features in greater detail. If you or a friend has Internet access, you can also learn more about interpreting what you see on your sonar screen. Visit our web site, WWW.LOWRANCE.COM. Be sure to check out the free Sonar Tutorial, which includes animated illustrations and more pictures of actual sonar returns, all described in detail. There's even a "printer friendly" version of the tutorial available on our web siteit makes a great supplement to this operation manual! For the ultimate training aid, be sure to download the free emulator software for your unit. Aside from being just plain fun, this program can help you learn both basic and advanced operations without burning boat fuel! Lowrance is the first sonar manufacturer to provide this type of training tool for customers. This PC application simulates the actual sonar unit on your computer. You can run it from your computer keyboard or use your mouse to press the virtual keys. Easy download and installation instructions are available on our web site.
Free training emulator is available for your unit on our web site.
Section 4: Sonar Options & Other Features
Material in this section is arranged in alphabetical order. ASP (Advanced Signal Processing) The ASP feature is a noise rejection system built into the sonar unit that constantly evaluates the effects of boat speed, water conditions and interference. This automatic feature gives you the best display possible under most conditions. The ASP feature is an effective tool in combating noise. In sonar terms, noise is any undesired signal. It is caused by electrical and mechanical sources such as bilge pumps, engine ignition systems and wiring, air bubbles passing over the face of the transducer, even vibration from the engine. In all cases, noise can produce unwanted marks on the display. The ASP feature has four settings Off, Low, Medium and High. If you have high noise levels, try using the "High" ASP setting. However, if you are having trouble with noise, we suggest that you take steps to find the interference source and fix it, rather than continually using the unit with the high ASP setting. There are times when you may want to turn the ASP feature off. This allows you to view all incoming echoes before they are processed by the ASP feature.
At left, Sonar Menu with Sonar Features selected. In the Sonar Features menu, Noise Rejection is selected with ASP in the default low setting (center, dual-frequency menu; at right, single-frequency menu).
To change the ASP level: 1. From the Sonar Page, press MENU| to SONAR FEATURES|ENT. 2. Press to NOISE REJECTION|ENT. 3. Press or to select a setting, then press ENT. 4. To return to the previous page, press EXIT|EXIT. 43

Alarms

This unit has three different types of sonar alarms. The first is the Fish Alarm. It sounds when the Fish I.D. feature determines that an echo is a fish. Another alarm is the Zone Alarm, which consists of a bar on the side of the screen. Any echo on the chart that appears inside this bar triggers this alarm. The last alarm is the Depth Alarm, which has both a Shallow and a Deep setting. Only the bottom signal will trigger this alarm. This is useful as an anchor watch, a shallow water alert or for navigation. Depth Alarms The depth alarms sound a tone when the bottom signal goes shallower than the shallow alarm's setting or deeper than the deep alarm's setting. For example, if you set the shallow alarm to 10 feet, the alarm will sound a tone if the bottom signal is less than 10 feet. It will continue to sound until the bottom goes deeper than 10 feet. The deep alarm works just the opposite. It sounds a warning tone if the bottom depth goes deeper than the alarm's setting. Both depth alarms work only off the digital bottom depth signals. No other targets will trip these alarms. These alarms can be used at the same time or individually.
At left, Main Menu and Sonar Alarms command. At right, the Sonar Alarms menu. To adjust and turn on the shallow alarm: 1. Press ALARM.
2. Press to SHALLOW ALARM DEPTH|ENT. 3. Press or to change the first number, then press to move the cursor to the next number and repeat until the depth is correct, then press ENT. 4. Press to SHALLOW ALARM ENABLED|ENT|EXIT. 44
5. To turn off the alarm, press ALARM|ENT|EXIT. To switch to a different depth setting, open the Sonar Alarms menu and repeat the instructions in step 3 above.
To adjust and turn on the deep alarm: 1. Press ALARM.
2. Press to DEEP ALARM ENABLED| to DEEP ALARM DEPTH|ENT. 3. Press or to change the first number, then press to move the cursor to the next number and repeat until the depth is correct, then press ENT. 4. Press to DEEP ALARM ENABLED|ENT|EXIT. 5. To turn off the alarm, press ALARM| to DEEP ALARM ENABLED|ENT|EXIT.
To switch to a different depth setting, open the Sonar Alarms menu and repeat the instructions in step 3 above. Zone Alarm The zone alarm is triggered when any echo passes inside the zone alarm bar, shown on the right side of the screen.
To adjust and turn on the zone alarm: 1. Press ALARM.
2. Press to ZONE ALARM ENABLED| to ADJUST ZONE|ENT.
At left, Sonar Alarms menu, with Adjust Zone command selected. At right, Adjust Zone Alarm selection box, with Upper selected.
3. To set the upper boundary for the Zone Alarm, use or to select UPPER, then press or to move the top of the bar to the desired depth.
LOWER, then press or to move the bottom of the bar to the desired depth. 5. Press EXIT| to ZONE ALARM ENABLED|ENT|EXIT. Now, any echo

Grayline

Grayline lets you distinguish between strong and weak echoes. It "paints" gray on targets that are stronger than a preset value. This allows you to tell the difference between a hard and soft bottom. For example, a soft, muddy or weedy bottom returns a weaker signal which is shown with a narrow or no gray line. a hard bottom returns a strong signal which causes a wide gray line. If you have two signals of equal size, one with gray and the other without, then the target with gray is the stronger signal. This helps distinguish weeds from trees on the bottom, or fish from structure. Grayline is adjustable. Experiment with your unit to find the Grayline setting that's best for you.
At left, Sonar Page menu with Grayline command selected. At right, the Grayline control bar.
To adjust the Grayline level: 1. From the Sonar Page, press MENU| to GRAYLINE|ENT. 2. The Grayline Control Bar appears. Press to decrease Grayline; press to increase Grayline. 3. When it's set at the desired level, press EXIT. 57

Fig. 1A

Fig. 1B

Hard structure

Fish near structure

Grayline Fig. 2A Fig. 2B

Hard bottom

Muddy bottom

Grayline Fig. 3A Fig. 3B
This series of figures shows how different Grayline settings can reveal more information. The "A" figures to the left show locations with Grayline set at the factory level of 64 percent. At right, the "B" figures show the same locations with Grayline increased to 84 percent. In Figure 1B, no fish are near the left structure, but the right structure shows fish holding next to the structure. Notice in figures 2B and 3B how Grayline displays a hard, rocky bottom (the drop-offs) with a wider gray line. The muddier bottom below those drop-offs appears as a narrower gray line.

HyperScroll

See the entry on Ping Speed, which controls the HyperScroll feature.

Noise Rejection

See the entry on Advanced Signal Processing in this section.

Overlay Data

To change the digital data shown on top of the sonar page: 1. Press MENU| to OVERLAY DATA|ENT. 2. Press or to select Data Type|ENT.
Overlay Data command on the Sonar Menu, at left. Overlay Data Shown selection menu, right. In this example, we scrolled down the data list to highlight "Water Speed."

Screen Contrast and Brightness
To access the Screen menu, press MENU|MENU|ENT.

Once in the Screen menu:

To adjust the display's contrast: The CONTRAST slider bar is already selected. Press or to move the bar. The left end of the scale is minimum contrast; the right end is maximum contrast. 63
Screen Command, left, and Screen Menu with Contrast bar selected, right.
To adjust the display's brightness: Press to BRIGHTNESS. Press or to move the bar. The left end of the scale is minimum contrast; the right end is maximum contrast. To adjust the screen's display mode: Press to DISPLAY MODE|ENT|press or to select mode|EXIT.

Display Mode menu.

Sensitivity & Auto Sensitivity
The sensitivity controls the ability of the unit to pick up echoes. Sensitivity can be adjusted, because water conditions vary greatly. a low sensitivity level (from zero to 50 percent) excludes much of the bottom information, fish signals, and other target information. High sensitivity levels let you see this detail, but it can also clutter the screen with many undesired signals. Typically, the best sensitivity level shows a good solid bottom signal with Grayline and some surface clutter. 64
Automatic Sensitivity The default sensitivity mode is automatic. The unit bases the sensitivity level on water depth and conditions. When the unit is in the automatic mode, sensitivity is automatically adjusted to keep a solid bottom signal displayed, plus a little more power. This gives it the capability to show fish and other detail. However, situations occur when it becomes necessary to increase or decrease the sensitivity. This typically happens when you wish to see more detail, so an increase in sensitivity is indicated. Or, wave action and boat wakes can create enough tiny air bubbles to clutter much of the water column. In that case, a decrease in sensitivity is indicated to reduce some of the clutter. The control bar used to adjust sensitivity up or down is the same whether the unit is in the automatic or manual mode. In automatic you can adjust sensitivity up to 100 percent but the unit will limit your minimum setting. In auto, the unit will continue to make small adjustments, allowing for the setting you selected. In manual mode, you have complete control over sensitivity, with the ability to set it anywhere from zero to 100 percent. Once you select a level in manual, the unit will continue to use that exact sensitivity setting until you change it or revert to auto mode. To adjust sensitivity in auto mode: 1. Press MENU|ENT. 2. The Sensitivity Control Bar appears. Press to decrease sensitivity; press to increase sensitivity. When it's set at the desired level, press EXIT. (When you reach the maximum or minimum limit, a tone sounds.)

Sonar Menu with Stop Chart command selected. The box is unchecked, indicating that the chart is scrolling across the screen.

Surface Clarity

The markings extending downward from the zero line on the chart are called "surface clutter." These markings are caused by wave action, boat wakes, temperature inversion and more. The surface clarity control reduces or eliminates surface clutter signals from the display. It does this by changing the sensitivity of the receiver, decreasing it near the surface and gradually increasing it as the depth increases. There are three levels of surface clarity available: low, medium, or high. It can also be turned off. The default level is off. To adjust the Surface Clarity level: 1. From the Sonar Page, press MENU| to SONAR FEATURES|ENT.
Sonar Features menu with Surface Clarity selected (at left, dualfrequency menu; at right, single-frequency menu).
2. Press to SURFACE CLARITY|ENT. 3. Press or to select clarity level|EXIT|EXIT|EXIT.
In the illustration at left, Surface Clarity is turned off. The right view shows Surface Clarity set at High.
Transducer Type (X126DF and X136DF only)
The dual-frequency units include the TRANSDUCER TYPE command. With this option you can tell your unit what type of transducer you're using, so that it can properly interpret the signals it's receiving. To change your transducer type, press MENU|MENU| to TRANSDUCER TYPE|ENT. Select the appropriate transducer type and press ENT|EXIT|EXIT.
At left, Main Menu showing Transducer Type command selected. At right, the Transducer Type menu, showing your three options.

Units of Measure

This menu sets the speed and distance (statute or nautical miles, meters), depth (feet, fathoms, or meters) and temperature (degrees Fahrenheit or Celsius). To change the units: Press MENU|MENU| to UNITS OF MEASURE|ENT.
Main Menu, left, Units of Measure Menu, right.
To set Speed/Distance Unit of Measure: Press or to change the Speed/Distance, then press ENT. After the option is set, press EXIT|EXIT|EXIT to return to the page display.

Upper and Lower Limits

See the entry in this section for Depth Range - Upper and Lower Limits

Zoom & Zoom Bar

"Zooming" the display is a common, fast and easy method used to enlarge small detail, fish signals and the bottom with its associated struc76
ture. This unit lets you zoom the display quickly and easily by pressing the Zoom In key, ZIN. Pressing ZIN once doubles the size (2X) of all echoes on the screen. Pressing it again quadruples the size of the echoes (4X). The zoom bar on the far right side of the screen shows which echoes will be displayed on the screen when the ZIN key is pressed. For example, pressing the ZIN key once will enable a 2X zoom which will show all echoes that are between the top and bottom of the 2X zoom bar. Pressing the key again will give a 4X zoom and only the echoes between the top and bottom of the 4X bar will show on the screen. Press the Zoom Out key, ZOUT, to return the display to the normal mode.

Sensitivity, 34, 39, 40, 41, 54, 55, 62, 64, 65, 66, 71, 81 Simulator, 34, 73 Software Version Information, 67 Sonar Chart Color Mode, 55, 68 FishReveal, 54 Sonar Chart Display Options, 31, 35, 36, 37, 68, 69, 70, 71, 72, 73
Zooming, 3, 31, 32, 35, 38, 69, 70, 76, 77, 80 Zoom Bar, 76 Zoom Pan, 77
Section 6: Supplemental Material
LOWRANCE ELECTRONICS FULL ONE-YEAR WARRANTY
"We," "our," or "us" refers to LOWRANCE ELECTRONICS, INC., the manufacturer of this product. "You" or "your" refers to the first person who purchases this product as a consumer item for personal, family or household use. We warrant this product against defects or malfunctions in materials and workmanship, and against failure to conform to this product's written specifications, all for one (1) year from the date of original purchase by you. WE MAKE NO OTHER EXPRESS WARRANTY OR REPRESENTATION OF ANY KIND WHATSOEVER CONCERNING THIS PRODUCT. Your remedies under this warranty will be available so long as you can show in a reasonable manner that any defect or malfunction in materials or workmanship, or any non-conformity with the product's written specifications, occurred within one year from the date of your original purchase, which must be substantiated by a dated sales receipt or sales slip. Any such defect, malfunction, or non-conformity which occurs within one year from your original purchase date will either be repaired without charge or be replaced with a new product identical or reasonably equivalent to this product, at our option, within a reasonable time after our receipt of the product. If such defect, malfunction, or non-conformity remains after a reasonable number of attempts to repair by us, you may elect to obtain without charge a replacement of the product or a refund for the product. THIS REPAIR, OR REPLACEMENT OR REFUND (AS JUST DESCRIBED) IS THE EXCLUSIVE REMEDY AVAILABLE TO YOU AGAINST US FOR ANY DEFECT, MALFUNCTION, OR NON-CONFORMITY CONCERNING THE PRODUCT OR FOR ANY LOSS OR DAMAGE RESULTING FROM ANY OTHER CAUSE WHATSOEVER. WE WILL NOT UNDER ANY CIRCUMSTANCES BE LIABLE TO ANYONE FOR ANY SPECIAL, CONSEQUENTIAL, INCIDENTAL, OR OTHER INDIRECT DAMAGE OF ANY KIND. Some states do not allow the exclusion or limitation of incidental or consequential damages, so the above limitations or exclusions may not apply to you. This warranty does NOT apply in the following circumstances: (1) when the product has been serviced or repaired by anyone other than us; (2) when the product has been connected, installed, combined, altered, adjusted, or handled in a manner other than according to the instructions furnished with the product; (3) when any serial number has been effaced, altered, or removed; or (4) when any defect, problem, loss, or damage has resulted from any accident, misuse, negligence, or carelessness, or from any failure to provide reasonable and necessary maintenance in accordance with the instructions of the owner's manual for the product. We reserve the right to make changes or improvements in our products from time to time without incurring the obligation to install such improvements or changes on equipment or items previously manufactured. This warranty gives you specific legal rights and you may also have other rights which may vary from state to state. REMINDER: You must retain the sales slip or sales receipt proving the date of your original purchase in case warranty service is ever required.

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Lowrance Pub. 988-0151-171 Printed in USA 111903
Copyright 2003 All Rights Reserved Lowrance Electronics

Cable connections for Lowrance X125 and X126DF, March 25, 2004 Sockets with blue socket nuts, and cable plugs with blue locking collars are NMEA 2000 connection types. However, the X125 and X126DF do not have a NMEA 2000 network socket or a communications port. These units cannot connect to a NMEA 2000 network and cannot transmit NMEA 0183 data. The NMEA 0183 data cable, the NMEA 2000 power cable and the white speaker wire are unused and should be capped with wire nuts or electrical tape.

Sonar unit rear view

PWR/DATA
Sonar socket Blue Power/Data socket
NMEA 0183 Data Cable. Four wires: blue, orange, yellow, shield (bare). Cable label says "RS-232 COMM."
SP-BL speed sensor. This is packed with the X126DF and is optional for the X125.
NMEA 2000 Power Cable. Three wires: red, black, shield (bare). Cable label says "NMEA 2000 Power."
Main Power Supply Cable. Cable has no label, but is thickest of the three. Three wires red (+), black ( ground), white. White is external speaker wire, not used in these units.
Skimmer transducer with built-in temp sensor
This figure corrects the drawings on pages 21 and 25 in the X125/X126DF manual, part 988-0151-171. It is a large-view supplement to the manual's Addendum I, part 988-0151-201.