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NOTE: The following manual was scanned with OCR software. Be aware that there may be a few misspellings or anomalies due to the inaccuracies of the software translation. Images are excluded due to the memory requirements; therefore, there will be references to illustrations that do not exist in this text only document.








INTRODUCTION to the TR-550-D Discriminator

The *'TR-550-D" is a discriminating metal detector, utilizing the inductively balanced

Transmit/Receive (TR) technique to provide excellent stability and sensitivity in an all-purpose

instrument. In the Normal mode the TR-550-D is a true all-metal detector.

In the "Discriminating" mode the "TR-550-D" makes an ideal detector for the serious

coin-shooter, allowing the operator to control the amount of rejection of unwanted "junk" targets.

Rather than a good/bad indication, the "TR-550-D" merely ignores unwanted targets, yielding, no

audio tone as the coil passes over them.


 Controls and Features of your TR-550-D

1) ON/OFF VOLUME CONTROL. Turning knob clockwise turns the instrument on and

increases the audio volume level. Rotating this control completely counterclockwise until it clicks

turns the instrument off. Since the audio indication for a detected target is an increase in volume

(loudness) in a TR detector, the volume control should be near maximum. If the volume control is

turned too low, weak responses to deep targets may be lost due to insufficient volume.


2) TUNING CONTROL. The Tuning Control is used to adjust the detector circuitry for

maximum sensitivity. Maximum sensitivity is that point at which the sound just starts. This point is

called the "Threshold."


3) MODE SELECTOR. This is a two-position toggle switch which is used to select the desired

operating characteristics of the detector, based on the type of searching being done. The two

positions are as follows:

a) Normal: In this position the detector will respond to all metals, both ferrous and nonferrous.

b) Discriminate: In this position, the detector will still respond to nonferrous metals such as gold,

silver, and copper, but will reject nails, tinfoil, bottle caps and other ferrous pieces of trash.


4) Discriminating Level Control. The control allows the operator to set the~ desired degree of trash

rejection while in the Discriminate mode. The amount of discrimination (rejection of unwanted

targets) is at minimum when the control is turned to "O" (fully counterclockwise) and increases as

the control is turned clockwise toward 10.


5) Earphone Jack. This jack enables operator to bypass the speaker for private listening by using

headphones. Headphones are especially desirable in noisy areas where background noise can

drown out the weaker signals which normally indicate the older, more valuable targets. The jack is

designed for standard 4-16 ohm stereo headphones with 1/4" plug. Variable volume type

headphones are recommended. These phones allow the unit to be set at full volume for maximum

sensitivity while adjusting the volume on the ear pieces to a comfortable listening level.


Push-button Tuning Button. The TR-550-D features a convenient thumb-push button at the tip of

the handle that eliminates the need to manually adjust the tuning control once the unit is tuned and

adjusted for searching. The push button is used as follows:

a) Hold push button in.

b) Turn tuning knob clockwise~ until the "Threshold" of sound is reached.

c) Release push button.

d) When retuning is required due to changing modes, discrimination level, or changing ground

conditions, simply depress button momentarily and release. This will retune the detector to the

original setting.


The "TR-550-D" has been designed for simplicity of operation, but, as is the case with any

detector, operator skill and familiarity with the instrument will determine, in large part, the success

of the hunt. We recommend that you read thoroughly the operating instructions and spend some

time familiarizing yourself with the instrument. The time you spend doing this will pay off

handsomely later.



Set the Normal/Discriminate mode selector switch to the desired position, based on the type of

searching being done.

Normal -- for relic or cache hunting when all metals including iron are wanted or when coin

hunting in areas relatively free of trash.

Discriminate -- searching for coins and jewelry (coinshooting) in trashy areas.




1. Turn the On/Off-Volume control fully clockwise.

2. Depress push button.

3. While holding push button depressed, rotate tuner control clockwise until sound just starts

(threshold) and then release button.

4. Lower the search coil to approximately 1/2 inch from the ground and press the push-button to

re-obtain the threshold if necessary. Raise the search mil slightly. If the sound level increases, the

mineral content of the soil is causing "detuning" of the circuitry.

The more heavily mineralized the ground, the greater will be this "detuning" effect. Lower the

search coil, retune with the button, and sweep the coil slowly across the ground, keeping the coil

the same height from the ground and being careful not to raise or tilt the coil at the end of the

swing, as raising it will give a false target indication (sound increase).


Sweep the coil across the ground in an are about 6 feet wide, advance about b inches and sweep

the coil back, overlapping each are. (See Search Techniques.) An object detected will cause an

increase in sound level.


It would be good practice to bury several coins at various depths in your yard and

practice detecting them to familiarize yourself with the instrument and its controls and to practice

pinpointing the buried objects.

When using the detector in short grass, the coil can be slid back and forth on top of the grass to

help maintain the constant height and maximum sensitivity.


Mineralized Soil:

In highly mineralized soil it may be necessary for an unskilled operator to detune the detector

slightly to avoid false target indications due to mineralization of the soil. By operating the unit just

below the threshold, the sensitivity is still good and the mineralization effect will have been

compensated for. Operating this way may be desirable even for a skilled operator on extremely

unlevel or mineralized ground.



All of the time you spend practicing with your detector will pay off in increased finds and in

digging smaller holes to recover them.




The Discriminate mode allows the operator to control the detector response to unwanted items

such as nails, tin foil, bottle caps, and aluminum pull-tabs. The amount of rejection of such "junk"

finds is controlled by the "Discriminate Level Control." The setting of this control has no effect on

the detector when used in the "Normal" made.


To begin searching in the Discriminate mode, place the mode selector in


the Discriminate position, and the Discriminate Level Control on minimum degree (O). When

changing from Normal to Discriminate, the threshold will be lost. Simply press the push-button to

retune to the threshold.


The unit is now adjusted to respond positively to all coins and jewelry but to ignore tin foil and

ferrous objects such as nails and rusty bottle caps. Aluminum is not being rejected at this setting.

Fortunately, almost all foil is tin foil and not aluminum foil. However, the aluminum pull-tab does

present a problem. The Discrimination Level Control can be increased to the point at which

pull-tabs are rejected. However, this causes some loss in sensitivity, and nickel coins and some

small gold rings are lost. Far this reason, mast serious coinshooters do not choose to reject

pull-tabs until it is absolutely necessary, such as under bleachers or around picnic tables.


Note that if the coil physically touches or passes extremely close to a piece of trash, you may

hear a sharp audio "blip." This blip is caused by the circuitry being overdriven, and the unit will

not give a normal target sound. To make certain that you have passed over a piece of trash, raise

the coil slightly and pass over it again. Only good targets will respond.



The electronic circuitry of this detector was designed to provide excellent stability but, as with

any detector, it is a good idea to check the control settings occasionally to maintain the best

sensitivity and discrimination level.





Stand Up Straight and let your arm hang down straight at your side. Adjust the telescoping

stem until the search head is about 1/2" above the ground. Adjust the search head so it is parallel to

the ground. Bounty Hunter detectors are designed for perfect balance so the detector should not be

"held up" with the arm bent as this can be very tiring.



With the detector held in the proper position, sweep the search coil side to ride slightly

overlapping each sweep as you move forward. Make sure the search coil stays the same height

above the ground and don't allow it to lift on the outside edges of the sweep.

Sweep speed and height of coil above the ground are usually) determined by the type of terrain

and sensitivity desired by the operator. When trying to obtain maximum depth, slow down.

Concentrate an the very weakest signals which often indicate the deeper (and usually more

valuable) targets. If you listen for strong signals, the ~weak signals will not be noticed. However, if

you concentrate on the faint signals, you will be sum to detect everything.


Target Pinpointing


When the detector signals a find, slowly sweep the search coil from side to side and then

forward and back until the strongest signal can be obtained. Your find will be directly beneath the

center of your search coil.

You will notice that the weaker signals are more easily pinpointed than the stronger ones. On

strong spread-out signals, pinpointing can be done very accurately by "detuning" the detector until

it is barely responding to the target. With push-button tuning, this can be done very simply. Once a

strong signal has been centered up, press the push button while holding the coil still over the target.

Release the button before moving the coil from the target and then re-pinpoint using the new

weaker response. Before going on to the next find, be sure to press the tuning button once more to

bring back maximum sensitivity.



To make sure you search an area thoroughly without gaps you may wish to lay out the search

area in a grid pattern. Stake out two parallel strings the width of your sweep (about three feet

wide) and sweep this area thoroughly. Next move one string over and make a new search area, and

so on until the entire area has been covered. You may also grid an area mentally using trees, rocks,

buildings, etc., as points of reference.



Approximately 90% of the problems from metal detectors are caused by weak, dead, or

improperly connected batteries. If the unit does not come on, or comes on but has weak volume,

will not tune properly, has erratic operation, or drifts -- CHECK THE BATTERIES


When replacing the batteries, make sure fresh batteries are purchased. Many units are received

at the factory for repair because bad batteries were replaced by "new" batteries with expired shelf




The TR-550-D is equipped with 9-volt transistor radio batteries (Eveready #216 or equivalent).


Access to the batteries is gained by pulling out on the nylon snaplok fastener on the battery

cover on the rear of the unit and removing the cover.


A battery lead connector snaps to the respective battery terminals. The "B" battery powers part

of the circuitry and the "A" battery powers the remaining circuitry, plus the audio output.


Batteries should last from 15-30 hours of use, depending on the make and freshness of the

batteries and the length of hunt periods. Using headphones will extend the battery life of the "A"



When replacing the battery cover, insert the cover tabs in the slots, close the cover inserting the

snap-lok fastener through the round hole and press the fastener until it snaps into the locked




When the detector is to be stored for a month or more, it is a good practice to remove the

batteries from the unit as weak batteries can vent and leak. This leakage is corrosive and can do

serious damage to the unit.




Metal detectors are sensitive electronic instruments. Although it does not have to be babied,

reasonable care must be taken to help ensure a long, trouble-free life for your detector.


KEEP IT CLEAN -- Take a few minutes after each use to remove dirt and dust. Wipe the

housing and wash the coil, especially if it has been dipped in salt water. A plastic bag over the

control box at the beach will help protect the unit from sand and prevent corrosion due to salt air.


KEEP IT COOL -- Never store your detector in an extremely hot environment, such a; an

automobile trunk in the summer, for extended periods of time. The prolonged heat will not only

shorten battery life considerably, but can cause electronic component breakdown.


KEEP IT SAFE -- Never transport your detector in such a manner that will subject it to extreme

vibration or shock. The unit may be cushioned by wrapping it in a blanket or by putting it in a

carrying bag designed for the purpose.




1. Use headphones! They are more sensitive than the speaker and will greatly increase the audio

battery life


2. Always try to run the coil as close to the ground as possible. Coil covers are available to protect

the coil when scrubbing the ground.


3. In order to thoroughly cover an area, always search in both directions. Many deeper coins on

edge might be missed going North and South, but detected going East and West.


4. After you have dug up a coin, always recheck the hole. It is not unusual to find several coins in

one hale.


5. If a strong signal is received but then lost after cutting a divot, check the loose dirt at the bottom

of the hole for a coin on edge.


6. In order to do the very best in a particular area, try searching immediately following a good rain

while the soil is damp.

The longer an item is buried, the larger it appears to the detector. This halo effect is more pronounced

when the soil is damp. Not only are the signals stronger at this time, but probing is also easier

when the ground is soft.


7. Don't worry about how many times a particular area has been searched. Usually the very best

finds still remain in a supposedly "worked" area. Persistence and a positive attitude are the two

main ingredients for successful treasure hunting.


8. Use your imagination. It's your best source for ideas of places to search possibly productive

areas previously overlooked by other TH'ers. but ...


9. Also listen to the "pros" with many years of TH'ing experience. If they say that old church

yards are good for old coins, or swimming areas are the best places to find lost jewelry, etc., you

can bet that they know what they are talking about.




Help protect our great hobby by respecting the rights of others. Always obtain permission

before searching on private property. Be extremely careful with your probing, picking up and

discarding trash, and ALWAYS COVER YOUR HOLES.

This webpage brought to you by White River Preparium


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