Digital Depth Sounder

OPERATING GUIDE

Contents

Unpacking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Installing the QT 206. . . . . . . . . . . . . . . . . . . . . . . . . . 3

Transducer Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Power Cable Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Installing The Transducer . . . . . . . . . . . . . . . . . . . . . . . 5 Transom Mount Transducers . . . . . . . . . . . . . . . . . . . . . 5 Through-the-hull Transducers . . . . . . . . . . . . . . . . . . . . 8 Low Profile Transducers . . . . . . . . . . . . . . . . . . . . . . . 9 Stem-type (power Boat Bronze) Transducers . . . . . . . . . . . . 10 Inside-the-hull Transducers . . . . . . . . . . . . . . . . . . . . . 12

Understanding Sonar . . . . . . . . . . . . . . . . . . . . . . . . 14 Air Echoes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Setting The Shallow Water Alarm . . . . . . . . . . . . . . . . . . 15

Shallow Water Sensitivity . . . . . . . . . . . . . . . . . . . . . . 16 When to Use Less Sensitivity . . . . . . . . . . . . . . . . . . . . 17 When to Use More Sensitivity . . . . . . . . . . . . . . . . . . . . 18

Troubleshooting Guideline . . . . . . . . . . . . . . . . . . . . . 19

Features, Specifications, and availability of Optional Accessories are all subject to change without notice.

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UNPACKING

Your QT-206 Depth Sounder box should contain the following items:

???Transducer with 3 lugs attached

???Power Cable (attached to the gauge)

???Mounting Bracket and hardware

???This Operating Guide

If any items are missing or damaged, please contact your dealer immediately.

FEATURES

??Depth Readings ??? The QT-206 is designed to give depth readings from 2.5 feet to a maximum depth of 199 feet. Depth readings are in 1/10 foot increments from 2.0 feet to 15 feet, and are shown as whole numbers up to 199 feet. These readings are displayed on a large Liquid Crystal Display (LCD).

??Night Viewing ??? The QT-206 is back lit at all times with a soft glowing lamp designed to help your night time navigational needs.

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INSTALLING THE QT-206

1.Find a location on your dash panel which will provide clear viewing and access to the LCD window.

2.After finding the right location for the indicator unit, mark a 2-inch hole to be cut out.

3.Check behind the panel for any cables or wiring which could be damaged. Then cut out the 2-inch hole.

4.Test fit the unit in the hole, and make any adjustments with your saw or drill.

5.Extending out of the back of the instrument is a brass shaft. Attach the U-shaped mounting bracket over this shaft, and place the washer on the shaft. Thread the nut onto the shaft until the U-shaped bracket is firmly against the back of the dash panel.

6.Look at the front of the instrument to ensure that it is aligned properly. Then tighten securely.

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TRANSDUCER WIRING

On the rear of the unit, locate the terminal lugs extending out of the rear of the instrument. These terminals are used to connect the transducer wires.

When shipped from the factory, the transducer is wired with 3 female lugs attached. These lugs need to be inserted onto the male terminals located on the rear of the gauge.

The BLACK terminal is connected to the BLACK wire. The WHITE terminal may be connected to either the RED, BLUE, or WHITE wire. Connect the shield to the position marked ???SHIELD???.

SHIELD

BLACK

RED, BLUE, OR WHITE

If you need these female lugs, contact your Uniden Marine dealer.

POWER CABLE WIRING

Because the QT-206 has no ON/OFF switch, you will need to wire it directly to a power source which will turn the unit on as power is applied. It may be convenient to wire the power cable directly to the Ignition Switch so that when you turn the boat on, the depth sounder immediately starts working. Some boats have already been prewired and labeled for a depth sounder so that when the switch is turned ON, the depth sounder receives power.

Another method for cable wiring is as follows:

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1.Connect the main unit to a 12-volt battery using the power cable supplied with your unit. You may extend this cable as necessary, but you must observe proper polarity (i.e., RED is positive and BLACK is negative).

2.Connect the BLACK wire to the negative (-) battery terminal.

3.Connect the RED wire to the positive (+) battery terminal.

4.Make sure the connections are clean and tight so they do not vibrate loose during the boat???s operation. Occasionally clean any accumulated corrosion from the battery terminals.

5.If for some reason the fuse is blown, replace with a 1 amp fuse, normal blow.

DO NOT OVER FUSE! The unit consumes 0.25 amps of current when it is on. You will want to keep your battery fully charged.

INSTALLING THE TRANSDUCER

The three most popular transducer styles are:

???TRANSOM MOUNT ??? Ideal on boats with outboard engines, or on I/O driven boats.

???THROUGH-THE-HULL ??? Ideal for boats with Inboard engine(s).

???INSIDE-THE-HULL ??? Often called ???Shoot Through Transducer???; it can be used effectively if installation procedures are followed carefully.

TRANSOM MOUNT TRANSDUCERS

Selecting An Installation Location

Mount the transducer fairly close to the centerline (keel) of the boat, which will ensure minimum potential aeration over the acoustic window of the transducer. On twin drive installations, install the transducer between the drives.

On single drive installations, you should mount the transducer bracket on the side of the boat where the propeller blade is rotating downwards. This is usually the right (starboard) side. If possible, do not mount the

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transducer directly behind any strakes, ribs, intakes and outlets for live wells and/or engine cooling water, or any protrusion which may cause turbulence or cavitation. On slower, heavier displacement boats, good results can be achieved further from the keel.

FIBERGLASS V-HULL BOATS???TWIN ENGINE

(MODERATE TO DEEP-VEE DEADRISE ANGLE)

FIBERGLASS V-HULL MODERATE TO

LARGE DEADRISE

TRANSDUCER IS BELOW

STRAIGHT LINE

EXTENSION OF HULL.

HULL

DO NOT INSTALL YOUR TRANSDUCER UNDERNEATH A GASOLINE

OVERFLOW. THIS WILL DESTROY THE PLASTIC MATERIAL OF

THE TRANSDUCER AND THE BRACKET. THIS DAMAGE IS NOT COVERED UNDER WARRANTY. Also, do not use LOCKTITE??or any other solvents on the mounting hardware or transducer. These materials may destroy the transducer.

Mounting The Transducer

The transducer and bracket assembly should be oriented vertically with respect to the water to yield a vertically-directed acoustic beam.

1.Attach the transducer to the bracket as shown below.

2.Place transducer and bracket at the selected location on the boat transom. Align the bracket so that the bottom surface of the

transducer is even with the underside of the boat.

FIBERGLASS V-HULL BOATS???TWIN ENGINE

(MODERATE TO DEEP-VEE DEADRISE ANGLE)

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3.Mark the outline of each slot on the hull. Mark the screw locations 1/8" from the bottom of each slot, and drill four holes 3/4" deep with a 9/64" drill. The slots in the bracket allow 5/8" of vertical adjustment which can be utilized to lower the transducer further into the water to achieve optimal performance.

4.Using the sheet metal screws provided, attach and tighten the bracket to the hull so that the transducer projects 1/8" below the underside of the hull. A marine sealant such as RTV should be applied to the threads of the screws to prevent water seepage into the transom. Align the transducer so that the rear is 1/16 to 1/8" lower than the forward point (bow). Tighten all bolts and screws.

5.Route the cable to the QT-206, being careful not to tear the cable jacket. Make sure the cable is separated from the ignition, tachometer, alternator, or other electrical wiring. Do not remove the connector or splice or shorten the cable, as this will void the transducer warranty.

Transducer Replacement/Identification Tag

On most transducers manufactured after 1987, the operating frequency and part number is attached to the cable or is printed on a mylar tag near the connector end. Do not remove this tag since it identifies the

transducer and will help you identify the operating frequency of the

transducer. The QT-206 operates at 200 kHz. (Incorrect frequency will cause your instrument to operate improperly.)

Transducer Wetting

Immediately before launching your vessel, thoroughly wipe the face of the transducer with a detergent type liquid soap. This reduces the amount of time required for the transducer to establish good contact with the water. If this procedure is not followed, it may take several days for the complete ???wetting??? to occur, resulting in reduced performance of the instrument.

Transducer Painting

If a vessel is kept in saltwater, especially in the southern U.S., marine growth can accumulate rapidly on the transducer face and seriously reduce performance. If fouling does occur, use a stiff brush or putty knife to remove this growth. Wet sanding of the fouled transducer face is permissible with #220 or finer grade of wet or dry emery paper. (Use plenty of water.) Coating transducers with anti-fouling paint is often necessary to achieve consistent performance. All anti-fouling paints

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have a solvent base. However, some solvent bases will damage encapsulation materials and plastics to varying degrees. If you need

anti-fouling protection, use only paints with a mineral spirits base; do

not use acetone vinyl-based paints. Glochester (RULE) Durapoxy is a hard, mineral spirits-based paint that has been found to be virtually transparent to acoustic energy. Never apply paint to the transducer by spraying; use a brush or roller. A sprayed surface ???wets??? very slowly, and there are often microscopic air pockets under the surface which attenuate the sound energy.

THROUGH-THE-HULL TRANSDUCERS

The two most popular styles of Through-the-Hull Transducers produced are low profile types, which typically are 1-3/4" or 2" in diameter, or stem-type transducers, which typically have a 3/4" pipe thread and require a fairing block to level. The two most popular materials used are nylon and bronze. Choice of material depends upon the boat construction:

Wooden boats require the use of a bronze transducer or bronze fittings because when the boat is out of the water, the wood will dry out. When the fitting is installed and the boat is returned to the water, the wood will swell and possibly crack a nylon type of transducer. Therefore, bronze is recommended for all wooden boat applications.

Larger fiberglass boat manufacturers often request bronze transducers and fittings due to the size of the boat and the total number of fittings used in the installation. However, nylon transducers are better suited for this application because of their ease of installation, lower cost, and more complete seal to the fiberglass hull.

Selecting an Installation Location

The mounting location must provide a smooth flow of water over the face of the transmitting surface of the transducer. Bubbles will cause the instrument to read improperly and cause erroneous readings. The mounting location should have reasonable access from inside the vessel since the transducer will require tightening from inside the hull.

???On sailboats, mount the transducer where the acoustic beam will not be shaded by the keel. A spot forward of a fin keel with a minimum deadrise angle is preferred.

???On planing powerboats, locate the transducer off centerline 6" to 12" and before the first lifting strake (flat area).

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???Do not install it on a lifting strake since this is the area where air bubbles travel from the bow to the stern, to provide a smooth ride.

???On displacement power boats (trawlers), mount the transducer well aft and close to the centerline.

???On I/Os, mount the transducer close to the engine(s).

???On inboards, always mount the transducer well ahead of the propeller(s), and shafts.

IMPORTANT

Never mount a transducer in direct line or within 4 feet behind another through-hull fitting, the keel or rudder, zinc anodes, or other projections that would cause turbulence around the transducer when the boat is underway.

LOW PROFILE TRANSDUCERS

The low profile style of transducer is ideal for high speed sport boats and sailboats. This style of transducer is designed to be mounted flush against the hull without a fairing or leveling block. The hull deadrise angle must not exceed 10?? in order to use this transducer fitting.

Mounting the Transducer

1.Drill a 1/8" pilot hole in the preferred transducer location.

2.Drill a 1-3/4" or 2" hole through the hull using the pilot hole as a guide.

3.Have some type of soft backing plate or thin piece of plywood (3-1/2" x 3-1/2" x 1/4" thick) available to strengthen the inside of the hull around where the hole was drilled. This serves the dual purpose of allowing the transducer to conform to the inside of the hull while preventing the transducer lock nut from unwinding. If you have a plastic housing, do not use wood shim. Use a fiberglass, plastic, or brass washer instead.

4.Route the transducer cable through the hole in the hull.

IMPORTANT

Do not pull on the cable as this may cause internal damage to the transducer by causing an internal wiring short.

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5.Apply a 1/8" thick layer of sealant around the lip of the plastic or bronze housing. A thin layer should also be applied up the sidewalls to a height of 1/4" greater than the hull thickness. This will ensure there is sealant material in the threads to seal them, and hold the housing nut securely in place.

6.From the outside of the hull, push the housing (with sealant applied) into the drilled hole. Apply a twisting motion to the housing to squeeze out excess sealant.

GASKET

(OR RUBBER)

HULL

SEALANT

7.Put the nut on the transducer from the inside of the hull. If nylon, hand tighten only.

8.Clean off any excess sealant from around the transducer.

STEM-TYPE (POWER BOAT BRONZE) TRANSDUCERS

The stem-type transducer is popular as a replacement transducer since it was the primary style used on older boats. The stem will fit the same size hole as a previously defective or obsolete transducer. Also, if your hull has a steep dead rise, the stem-type transducer will be best suited for your application. However, because of the smaller diameter shaft going through the hull, a fairing block should be used so that the transducer can be oriented straight up and down. Fairing blocks are best made out of hard wood such as oak. The shape of the block will be determined by the shape of your hull and the style of transducer you choose.

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3/4"

PIPE

THREADFAIRING

1 1/4 "

3"

Mounting the Transducer

1.Drill a 1/8" pilot hole in the preferred transducer location. Refer to the previous section to determine the best location for your type of boat.

2.Drill a hole ???slightly??? larger than the stem of the transducer. Be careful not to make it too large as you will run the risk of water leaking into the hull.

3.Cut the fairing block to the shape of your hull and insert the cable and stem of the transducer through half of the fairing block.

4.Apply a good grade of underwater marine sealant (polysulfide compound) to the flange on the transducer and to the surface of the leveling block where the block touches the outside of the hull. Apply enough sealant so that it beads out around the transducer as you tighten the transducer nut.

5.Put the remaining half of the fairing block on the inside, over the transducer, along with sealant next to the hull. Tighten lightly with a wrench.

6.Clean off the excess sealant from around the transducer.

IMPORTANT

After launching the boat, be certain to check the transducer location for leaks.

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INSIDE-THE-HULL TRANSDUCERS

This type of transducer does not require the drilling of a hole as does the Through-the-Hull Transducer. However, since the sound waves transmitted and received by the Inside-the-Hull Transducer must pass through the hull, transducer performance will be reduced. The success of Inside-the-Hull installation is greatly dependent upon the purity of the hull directly below the transducer and the type of hull. Inside-the-Hull mounting should not be used on aluminum hulls, balsa core hulls, wooden hulls, or hulls where the deadrise angle is more than 15??.

To reduce sound transmission losses, the adhesive used to bond the transducer to the hull should conduct sound at speeds close to that of the plastic or epoxy face of the transducer and the polyester resin of the hull. Epoxy adhesives, as opposed to silicone, are recommended.

Note: When performing an Inside-the-Hull installation, you must use a special Inside-the-Hull Transducer since it contains a transducer crystal which is wider in diameter, and is designed to transmit the pulse through the hull. Do not attempt to use a Transom Mount Transducer, as the crystal is too small to ensure optimum instrument results.

Selecting an Installation Location

The transducer should be located where the hull laminate is dense and has no entrapped air. Generally, best operation is obtained by mounting the Inside-the-Hull Transducer on the centerline of the hull, as it allows a flat, horizontal mounting area for vertical orientation of the sonic beam. Do not choose an area above a lifting strake, as air travels underneath the hull here and could cause erroneous readings.

???On sailboats, mount the transducer near the centerline and forward of the leading edge of the keel.

???On power boats, mount the transducer as far aft as practical.

???On I/Os, mount in a spot near the engine.

???On inboards, locate the transducer forward of the prop(s), where it will not be shaded by prop shafts.

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Use one of the following methods to determine if your chosen location is satisfactory:

1.Place the transducer in a plastic bag filled 1/2 to 3/4 full of water. Tie or tape the bag tightly around the transducer cable. Wet the selected location and place the bag against the hull, pressing the transducer face against the hull. If the hull is void free at this point, the depth sounder should now operate.

2.Coat the face of the transducer with silicone grease or petroleum jelly. Then press with a twisting motion against the hull. If the hull is void free at this point, the depth sounder should now operate.

Mounting the Transducer

1.If the interior surface of the hull at the selected spot has a rough pattern, grind it with a disc sander until smooth. Any grease or oil on the surface must be removed.

2.Mix the two-part epoxy supplied with the transducer for at least 3 minutes. If this is not done, proper bonding of the transducer to the hull will not occur and false readings can occur. The working time of the epoxy is 5 minutes. The hull temperature must be 60?? or higher for the epoxy to bond sufficiently.

3.Apply the mixture to the clean location on the hull and to the face of the transducer in a small amount.

4.Press the face of the transducer into the spot of epoxy. To remove any air bubbles, slowly rotate in one direction only, until the transducer is physically against the hull or within 1/4" of the hull.

When the epoxy has cured, it should be permanently bonded to the hull and hard to the touch. Test the epoxy which extends out of the underside of the transducer with a screwdriver to ensure that it can???t be dented, and that it is completely hard. Epoxy which is not hardened will eventually cause improper readings.

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UNDERSTANDING SONAR

All depth sounders emit ultrasonic sound signals from the transducer into the water located under your boat. These sound signals travel through the water at a rate of approximately 4,800 feet per second (1500 meters per second). The depth sounder transmits a signal and receives a returning echo. The unit calculates the amount of time in microseconds that elapsed while the signal traveled down to the bottom and returned back to the transducer. This time is then converted to depth and displayed on the screen.

It may help to understand these sound signals traveling between the transducer and the bottom by imagining a ping-pong ball bouncing up and down from the floor. The closer the ball is to the floor, the less time it takes for it to return. The higher the ball is bounced, the longer it takes to return. Bouncing the ball off a hard surface such as cement is the same as bouncing a signal off a sandy or hard bottom. Bouncing this same ball off carpeting creates a totally different effect because the ball returns with less force. The same principle applies to an echo bouncing off a muddy or grassy bottom, causing the echoes to be weaker.

AIR ECHOES

Air echoes can be caused by excessive turbulence under the face of the transducer. Ultrasonic signals from a transducer will not penetrate air. They react to air in the same manner as they react to a hard bottom described above. Therefore, if your transducer is not mounted properly and you are getting turbulence (air bubbles) under your transducer, you may get false readings. This is simply because signals are being returned by the turbulence and are never reaching the bottom.

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SETTING THE SHALLOW WATER ALARM

Located just below the LCD window are two keys labeled ???DOWN??? and ???UP??? Alarms. These keys are used to set the Shallow Water depth alarm so that it will audibly alert you if you enter water shallower than your preset depth alarm.

To set the alarm, press the ???DOWN??? key. The LCD shows an alarm depth of A03. Pressing the ???DOWN??? continuously cycles the alarm setting deeper by one foot increments from A03 through A10 (for example: 3, 4, 5, 6, 7, 8, 9, 10). After A10, the alarm settings are by 2-foot increments (for example: 10, 12, 14, 16, 18, 20 feet). The alarm settings jump by 5-foot increments (for example: A20, A25, A30).

When you see a digital readout proceeded by an ???A???, this is your ALARM setting. This number appears in the display window immediately after you press either alarm key and then will disappear after several seconds. This number remains in the unit???s memory until power is turned off.

To decrease the alarm setting, press the ???UP??? key. The display will show these numbers in decreasing value so that the alarm is shallower. Several seconds after you press either the ???UP??? or ???DOWN??? keys, the instrument displays the actual depth reading. A00 indicates the alarm is off.

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SHALLOW WATER SENSITIVITY

The Shallow Water Sensitivity controls a circuit in the depth sounder that affects the first 10 feet of water. It alters the system???s response time in this area only, and can be used to compensate for installation imperfections.

Example:

???SHALLOW READINGS: If your instrument occasionally displays random, false shallow readings such as 3.1???, 2.8???, and 4.3???, you may need to adjust this control.

???DEEPER READINGS: If your unit is reading false echoes which are deeper than the actual depth, you may not have enough sensitivity, which can also be corrected by using this control.

??????0.0??? READINGS: Adjusting this control too far in either direction could affect your readings. For example, if the adjustment is at an extreme, it could actually cause the unit to give a ???0.0??? reading at a deeper depth. The true depth could be 30 feet, and if the control is too far counterclockwise, the readout could be ???0.0???.

This adjustment fine tunes the installation of your gauge to the location of the transducer on your boat and to the waters where you do your boating. It is typically an adjustment that is made by the boat owner since it is performed while the boat is in the water.

Each depth gauge is tested at the factory with a transducer located in a water tank. The Shallow Water Sensitivity is then factory preset. However, after installation for your local waterways, you may need to perform this minor adjustment so that the depth gauge operates at its maximum potential on your boat.

With Inside-the-Hull Transducer installations, it is especially important to perform this adjustment. It is impossible to control the many types of hull configurations on the many varieties of boats available today. Since fiberglass hulls are generally hand-layered, the hull thickness can vary from boat-to-boat even though they may be the same model. Thickness of the fiberglass combined with the many types of bottom conditions (sandy, rocky, muddy) can affect the readings on your digital depth sounder. This control enables you to tune your gauge more precisely so that the unit reads properly. Unless major changes take place in your boating environment, you should not need to adjust this setting again.

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WHEN TO USE LESS SENSITIVITY:

SHALLOW READINGS

Use less sensitivity when your instrument displays a series of random, shallow readings (3.5???, 2.9???, 4.1???) and the actual depth is greater.

How to Perform

When looking at the rear of the instrument, this adjustment is made in a clockwise direction. (This control operates much like the volume control on a radio. If you turn it all the way down, you cannot hear the music.

Turning it up too far makes the music blare and sound out of tune.) Turning the sensitivity control too much can actually ???squelch??? out the transmit pulses and the return echoes. This will result in a ???0.0" reading in the display window.

Note: When making this adjustment, turn the control no more than 1/16th of a turn at a time. Then wait 3 to 4 seconds before making the next adjustment turn.

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WHEN TO USE MORE SENSITIVITY:

DOUBLE ECHOES (READINGS TOO DEEP)

Use more sensitivity when your instrument displays depths that are too deep; that is, greater than the actual depth. For example, if you are in 6??? of water and turn this control too far in the less sensitivity direction, you may see ???12.0?????? appear in the LCD window. This is very dangerous since you will actually be operating the boat in shallower water than what is displayed. Caution should be exercised to locate the Sensitivity Control somewhere between both ends of the rotation.

How To Perform

By rotating the control in a counterclockwise direction (when looking at the rear of the instrument), you can increase the sensitivity of the gauge to the first 10 feet of water. Increasing this adjustment too much in the MORE SENSITIVITY direction can cause a ???doubling??? of the actual depth.

Note: When making this adjustment, turn the control no more than 1/16th of a turn at a time. Then wait 3 to 4 seconds before making the next adjustment turn.

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TROUBLESHOOTING GUIDELINE

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