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Teknetics 8500

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.

Teknetics 8500 Operations Manual

"B" SERIES SUPPLEMENT For Owners Manual Audio Target Identification description:

A.T.I. is an abbreviated term for Audio Target Identification". Buried "targets" can now be identified by a certain audio pitch that is unique to the metal object located.

With the New 8500B, or 9000B series you simply set the reference pitch with the TONE control, sweep over the Target, and "Hear" the difference between Coins and Trash.


You will notice that on the 8500B and 9000B the VOLUME control has been replaced by a TONE control. The Target ID switch also serves a slightly different function on the "B" series.

In the "OFF" position several things happen--the Audio Target Identification (A.T.I.) is not functional, thus the TONE control acts only as a normal "Tone Control". However, Visual T.l. is still functional and is activated by two or three sweeps over the target. In the Low, Medium, and High positions the A.T.I. as well as visual T.I. is functional. In these positions the TONE control sets the A.T.I. "reference pitch". The "Low" position normally requires only two to three sweeps to identify the target. The "Med" position re quires seven or eight sweeps to identify a target. However, it is usually much more accurate on "marginal'' targets. The "High" position is for use in areas where the detector is subject to high interference, such as Competition Treasure Hunts. This position has less sensitivity and requires only two or three sweeps to identify the target.

To use A.T.I., start with the detector properly tuned and ground balanced in the GB Mode. Set the "MODE" switch to "G" "DISC" and the "Target I.D" switch to the "Low" position. Next, the A.T.I. "reference'' should be set.

The "reference pitch" is simply a TONE control setting with a pitch that is the same as that caused by a specific target. As an example to set a Nickel reference, turn the TONE control fully CCW and set the DISC. ADJUST at "2". Wave a Nickel past the loop until the Meter reading shows a Nickel-- Note the pitch and Meter reading. Next increase the TONE control to about 12:00 on the dial and tap the Push Button. The pitch and Meter reading should be nearly the same, if not--slightly readjust the TONE-, tap the Push Button and again check to see if the pitch and Meter reading are the same as the nickel. In some areas that you hunt you may want to use a pull tab, common to the area as your "reference pitch". Thus, the pull tabs will change only in volume and not in pitch. Nickels will however cause a decrease in pitch along with an increase in volume.

Now as you are searching in GB DISC, with a Nickel reference -- iron will cause the sound to go quiet. Foil will cause an increase in volume and a decrease in pitch. A nickel will cause an increase in volume with no change in pitch. A pull tab will cause an in crease in volume and pitch and a dime will cause an increase in volume and have a much higher pitch than that of the pull tab. "Good" targets such as Coins will normally "Lock-on'' have a good stable tone and meter reading), whereas most "bad" targets will give unstable readings.


Depth Reading:

Make a simple sweep directly over the target. (Avoid sweeping over any other nearby targets). The depth of the target will "lock-on" and can be read directly from the depth scale.


Accidentally sweeping over nearby targets or not resetting prior to a depth check can cause Incorrect depth readings.

P.B. Operation:

When the Target I.D. switch is In the Low, Medium, or High positions--a quick momentary tap of the push button will reset the A.T.I., visual T.I., and lock-on depth. However, if resetting is not desired - then the push button needs to be held in for longer than one second, as In Mode changing.


Teknetics is a corporation formed by individuals who are dedicated to the premise that the pro ducts they manufacture should have lasting quality, the latest in design technology and the maximum range of features that can be obtained for your money.

With these goals in mind, from its first inception, your detector was designed by an engineering group which has many years invested in the field of detectors, having already designed the major innovations in use by other manufacturers.

By carefully reading the instructions in this manual, you will! obtain all of the advantages designed into your instrument, but the best performance can only be achieved by practice until you are proficient enough to be able to identify even the slightest variation in target response.



Applications Limitations



Alternate Batteries

Checking Battery Condition

Glossary of Terms

Identification of Controls



Ground Balancing

Ground Balance Discriminate

Target Identification

Depth Reading

T.R. Discriminate

Push Button Mode Changing

Tips on Operation

Field Application

Detector Care & Service


Six Year Limited Warranty

A Peek Inside


Metal detectors are used to locate unseen metallic objects Such desirable objects include coins, rings watch, pistols, rifles, relics, etc... Metal detector will not sense nonmetallic objects such as wood, paper, plastics, or cloth.

The following is a list of uses, but is not limited to these uses exclusively.

COINSHOOTING - A hobby devoted to locating coins in parks, school yards, beaches and other areas where the public is likely to lose money. Some specialize in only digging on weak signals increasing the likelihood of finding older, more valuable coins that are usually silver.

RELIC HUNTING - Areas involved in past wars, such as the civil war. Indian campaigns, etc.., provide many articles from the past such as cannon balls, mini balls. shells, guns, medals, swords. uniform buttons knives, etc.... Other areas to locate articles of history would include old mining towns and areas occupied by early settlers.

PROSPECTING Searching washes and gullies or old tailings from mines has often revealed nuggets of gold. From time to time even very large nuggets weighing many ounces are reported being found with metal detectors.

BEACH COMBING - Along beaches visited by people everywhere are to be found coins, watches, rings, bracelets, portable radios, etc... And the digging is easy!

SURVEYING - Iron stakes established in earlier surveys can be more easily located, especially when overgrown with weeds, and covered with debris.

LOGGERS - Nails, spikes, etc., can be easily located before costly damage to an expensive blade and eliminate danger to the operator.

LAW ENFORCEMENT- Using a metal detector to systematically sweep suspected areas for discarded weapons or stolen property is a common practice today.

PIPES AND CABLES - Before causing damage, a metal locator can be used to determine the loca tion of buried pipes and cables prior to digging.

There are just a few of the many possibilities. Areas to search are limited only by your imagination tion.


Carefully unpack your detector and check to see that you have all the parts shown.

Assemble the detector by placing the lower rod onto the upper rod. Wrap the cable around the rod and connect to the loop plug on the case as shown.

Note: At this time you may need to charge the batteries.


Your new Teknetics detector is equipped with factory installed rechargeable Nickel Cadmium batteries which will save many hundreds of dollars in battery purchases as they may be recharged as many as a thousand times or more.

The batteries will require charging for a period of 14 to 15 hours lo bring them to full capacity, as they are shipped in the unit only partially charged. It is not necessary to remove the batteries to recharge them. Simply plug the charger into the charger socket on rear of detector and connect to an electrical outlet. Once charged, a minimum of seven hours continuous use can be expected.

Nickel Cadmium batteries can develop a memory pattern limiting their available capacity. If they are used in the instrument, for example, for two hours each time and then recharged, the capacity will be reduced to this amount. Should this happen, recharge the batteries and use the instrument until it will no longer operate and then recharge.

There are two charge modes available. For nor mal charging set the POWER switch to "Norm". If the batteries are completely discharged, 14 hours of charge time is required to fully charge. For a partial charge, a good rule of thumb is two hours charge time for each hour of use.

The second mode of charging is for storage. Once the cells have been fully charged, the Power switch can be set to the "Store" position. In this mode, the unit will receive a small "Trickle" charge that will keep that batteries at full charge. This way the instrument is ready to use at all times with full capacity available.

The "store" charge is intended for short term storage and should be used no longer that two or three months at a time.


Fourteen (14) 1' volt AA Penlight Alkaline batteries may be used instead of the NiCads sup plied if they are in need of charging and time is not available 10 wait.

Remove the compartment doors on the bottom of the case and remove the cells being sure to store them so they will not ---. Install the Alkaline cells according to the legend for + and -.

CAUTION DO NOT CONNECT THE CHARGER T0 THE INSTRUMENT WITH ANY BATTERIES INSTALLED EXCEPT NiCads. There is danger of explosion which may result in not only damage to the instrument, but also personal injury


To check the condition of the batteries installed in the detector, turn the "POWER" switch to "ON" and the "DISPLAY" switch to "A" Batt for the "A" batteries, and to "B" Batt for the "B" batteries.

Fully Charged batteries will read full scale on the meter. After the first few minutes of operation, NiCads will drop to approximately 70 on the meter scale and remain at that level for the duration of the charge. 1.5 Volt Penlight Batteries (Alkalizes) will show a gradual decline in voltage during their operating life.

Recharge your NiCads or replace your 11/2 volt cells when the batteries read in the RED zones.


1. Threshold Tone - Barely audible tone set by the "TUNER" control to achieve the best sensitivity to a metal object.

2. Neutral Response - Indicates no change in threshold tone.

3. Negative response - Indicates reduction or loss of tone

4. Positive Response - Indicates an increase in tone.

5. Disc. - Abbreviated term for discrimination. Discrimination allows the detector to selectively reject certain metal objects or "junk".

6. G.B. Disc. - Abbreviated term for Ground Balance Discriminate. This mode allows both ground neutralization and selective discrimination at the same time.

7. G.B. - Abbreviated term for Ground Balance. Ground Balance is achieved by adjusting the "GND BALANCE'' control for the neutral response to the mineral content in the ground.

8. G.B. Max. - Abbreviated term for Ground Balance Maximum. This mode is the same as the GB Mode but with increased sensitivity.

9. T.R. Disc. - Abbreviated term for Transmit Receive Discriminate. This is a non-ground canceling discriminate mode.

10. Target ID - Target Identification, used with G.B. DISC. Mode. to identify detected metal objects.

11. Target -- refers to any object sensed by the detector.

12 CW - Clockwise

13. CCW - Counter clockwise

14. Mineralization - Refers to soils containing ferric oxides or magnetic particles.

15. Halo Effect - Certain metals, when buried for long periods oxidize and leech into the surrounding soil. This results in a "metallic Halo" around the buried object.


1. Push button - Used for retuning and temporary mode selection.

2. Meter display provides target identification and depth. Also displays battery condition.

3. Tuner - Adjusts "Threshold" setting.

4. Mode - Selects primary mode of operation.

5. Target ID - Selects degree of target identification accuracy versus ground mineralization.

6. GND Balance - Adjusts the detector to "balance'' out or neutralize ground mineralization.

7. Disc. Adjust - Selects the level of discrimination desired by the operator.

8. Power - Turns the detector on and off and selects charge mode.

9. Display - Selects display of "A" or "B" battery condition or "operate" mode.

10. Volume - Adjusts loudness of Speaker or Headphone sound.


The Teknetics 8500 is a remarkably advanced and precision engineered metal detector. It features the very latest advancements in metal detector technology.

The amazing "Coin Computer" 8500 incorporates a unique Target Identification readout. The meter display provides a truly phenomenal wealth of information to the TH'er. A glance at the meter after a few sweeps over the target, will tell you with a great deal of accuracy what the find may be. The meter also indicates the depth at which coin sized objects are buried.

NOTE: The meter is scaled such that the marked off areas represent the most likely meter reading for a particular object. However, there may be some overlapping of target readings into adjacent areas due to such things as the "Halo Effect". Over a period of time you will begin to recognize where certain targets or even combination of targets tend to register on the T.I. scale.


1st BAND: Gold & Silver Coins

2nd BAND: Clad coins & trash

3rd BAND: ()-1 00 Scale 4th BAND: --- Scale

5th BAND: Battery Check

Proper tuning and ground balancing is essential in order to achieve optimum performance from your metal detector.

"Tuning'' means: First. adjusting your detector to its "Threshold" and second, adjusting or "balancing" out the ground mineralization at the site to be searched.

Start by setting the "Threshold" as follows:

CAUTION: Be sure the loop is at least three feet away from any metal area, and that your batteries are fully charged.

Set the controls as shown on page 13.

Press and hold in the push button on the handle and slowly increase the TUNER clockwise until a barely audible tone is heard. Release the push button. The detector is now tuned to it's "Threshold". Passing a coin near the loop will; cause an increase in the tone.

Once set, should the threshold change for any reason, other than actually changing the TUNER control, it can be reset by momentarily pressing the push button. retuning to threshold is one function of the push button. the other is mode changing - more on this later.


The objective of "ground balancing" Is to adjust the GND Balance control to a point at which the tuning Threshold does not change as the loop is lowered to ground level Mineralization present in the soil will cause with threshold tone to go up or down until the detector is properly ground balanced.

To ground balance the detector, hold the loop about three feet above the..ground. (The detector should be "ON" and adjusted to the tuning "Threshold" as previously instructed). The mode switch must be set to GB..or GB Max when ground balancing the detector. Lower the loop to within approximately an inch off the ground. As the loop nears the ground, listen to hear whether the threshold tone increases or decreases in volume.

This must be done as many times as necessary until there is no change in the threshold tone with the loop near the ground or in the air.

NOTE: If there is difficulty in making the adjustment, you may be over a hidden metal object. Move to another area and try again.


The G.B. Disc. Mode is a ground balanced discriminate mode. This mode relies on motion (sweeping the target) in order to function properly.

To use the G.B. Disc. Mode, start with the instrument tuned and ground balanced as described earlier. Next, set the controls as shown.

Good objects will respond with a good positive signal tone. Bad objects will cause a negative or broken tone. When the detector responds to a good target, switch the Mode control back to GB for pinpointing. GB can also be selected by pushing in and holding the push button.

NOTE: The discriminate adjust setting determines whether certain metal objects will cause a possible or negative audio response. For example, when set to reject pull tabs, nails, foil, and nickels will cause negative audio response.


Target identification can be used in conjunction with any mode to identify positive target responses. Changing to the G.B. DISC. mode and sweeping the loop over the Target activates the Target ID circuitry except in its "OFF" position.

The Target ID Switch has four (4) positions: Off, Low, Medium, and High. The "LOW" position is for use in areas containing very low mineralization or no mineralization such as some beach areas. This position requires at least two or three sweeps to identify the Target.

The "MED" position can be used in most areas of mineralization. This position requires at least six or seven sweeps to accurately identify a target.

The "HIGH" position is for use in areas of very heavy mineralization or areas where the detector is subject to a lot of interference, such as club treasure hunts. This position also requires at least six or seven sweeps for accuracy.

To use the Target ID, start with the detector pro perly tuned and ground balanced in the GB mode. Turn the Target ID Switch to the position most suited to the area being searched. In most cases the "MEDIUM" position will work best -use it if you are not sure of the mineralization in the area.

Proceed to search the area. When a target Is located simply switch to the G.B. DISC. Mode and sweep the loop back and forth over the target six or seven times - stop - and look at the meter. The probable target will be indicated on the upper scales of the meter. The Target ID reading will remain unchanged until a new target is check.

Note: The Target ID Mode is equipped with Target Signal Overload alarm. When swinging the loop over a target if the audio tone should momentarily drop in frequency, this is a warning, the circuits have been overloaded by a too strong signal. (This overload will not harm the detector). The Target Identification reading will not be accurate. If this happens, you will have to begin over and slow the sweep down or sweep the loop at a higher distance above the target. The overload signal functions only when the Target ID is on.

If you are in an area where many targets are close together, then use the G.B. Mode to identify the targets, since the G.B. Mode has a smaller apparent pick-up pattern. Remember the loop must be in motion to activate the Target Identification Circuits. Holding the Push Button in will give the T.I. reading.


The depth scale of the meter indicates the depth of a single coin up to six inches depth.

Once a good target has been located, press and release the push button to reset the depth scale. Then place the loop on the ground directly over the target (you will be centered over the target when the meter shows the closest distance to the target).

The depth reading works in all modes except G.B. DISC.


The TR Disc mode can be used on beaches, in houses, or other areas where mineralization is not present. The TR Disc mode will not cancel the effects of mineralized soil.

To use the TR Disc Mode, set the controls as shown

With the loop in the air. adjust the threshold as described earlier. Lower the loop to the ground. Press and release the push button to retune. Keep the loop level and at the same height above the ground while searching. Good targets will cause a sharp positive signal while bad targets will cause a negative response depending on the Disc. adjust setting.


As mentioned earlier, the push button is used to "Retune" by momentarily pressing it. The push button can also be used to change modes.

As an example if the mode switch is set to the GB Mode, pushing in on the push button and holding it in will switch the detector's GB Disc. Mode until the button is released.

The push button can also be used as an aid in pinpointing. As the loop is moved nearer the target, pressing releasing the push button detunes the target signal making it easier to pinpoint.

NOTE: When detuning to pinpoint, the depth reading will not be accurate.


1. This detector relies on motion to activate both GB Disc. mode and the Target ID circuitry. The following is an example of how this works:

2. Interpreting different types of responses:

You can tell many things about a target just by the sound response of the detector. As an ex ample, if you are using the detector in the GB Disc. mode with the Disc. adjust set to "Foil" you can expect the following results:

3. Sometimes targets close together will cause a confusing signal. Try sweeping from different angles to help isolate targets:

4. Pinpointing the target: Pinpointing is important, it helps to avoid damage to the object and ground.

"X"ing as shown helps to pinpoint the target: Target will be directly below "X" at point of loudest response.

5. Your 8500 can tell you many things about a particular target that can be helpful in determining whether or not lo dig. Make use of all the information available as an example:

Depth reading can be an indicator of in age older coins are usually deeper. The sound response can tell a lot -- a coin usually gives a good solid sound regardless of sweep direction. When checking a target, listen to the "Size" of the sound in the GB mode - a large target produces sound over a greater area than does a single coin. CAUTION: Because ring styles vary a great deal, rings may read anywhere on the Target I.D. scale. Our findings to date indicate that many ladies' gold rings will read almost the same as a nickel.

6. Respect the rights and property of others. Check local laws and ask permission to hunt. Always fill all holes and avoid damage to lawns.


Coin hunting, or coinshooting as it is sometimes called, is the use of a metal detector to locate coins and small jewelry wherever people have been and may have lost such items.

The Teknetics 8500 is an excellent coinshooting detector. To coin hunt, adjust the detector for normal outdoor use at the hunt site. Adjust the Discrimination control to the level of trash rejection desired. CAUTION: High discrimination settings will reject Nickels and small gold rings and gold coins. However, with the 8500 a very low discrimination setting can be used. When the discriminate audio tone signals a good target, the Target ID can be used to identify the target.

Once it has been determined the target is good, it's depth can be checked.

Carefully remove the target taking care not to damage the object. In lawn areas, caution should be exercised so as to not damage the grass or leave unsightly and dangerous holes.

NOTE: The discriminate control only affects the audio response - the meter will show all objects that are foil and above regardless of the Disc. adjust setting.

Freshly buried coins may not readout on the meter exactly the same as coins buried for a long time.


Old homesteads, ghost towns, and battle fields are some of the areas that may yield interesting and valuable old relics. Since most any item may be of interest, you might want to hunt these areas without using any discrimination or a minimum discrimination setting. In fact for the greatest depth possible, you may want to use the GB Max Mode.


The 8500 can be used to locate gold nuggets, silver and copper nuggets, and black sand pockets.

To hunt for nuggets adjust the detector for operation in the GB or GB Max Mode and search known gold or silver bearing regions. The loop can be submerse underwater for searching shallow streams. The instrument case is not waterproof - protect it from water or rain.


Beach combing is a lot like coinshooting except the digging is usually easier. A simple scoop with a screen or holes to allow the sand to escape works quite well.

Wetted beach sand is usually so conductive that maintaining ground balance may be difficult. You may find that it is best to ground balance over dry sand (if mineralization is present) and then switch to GB Disc. for searching over wet salt sand.

If the sand is non-mineralized the TR Disc. mode can be used. By adjusting the Disc. wet salt sand can actually be "Tuned" out normally between nails and foil on the dial.


The following precautions service tips will help ensure your detector's long life and performance.

Cleaning: The loop and rod are waterproof. They can be cleaned with fresh water and a mild non abrasive cleanser. The case can be wiped clean with a damp cloth. After cleaning, dry the instrument thoroughly. CAUTION: The detector case is not waterproof, and water if allowed to enter it will damage electronic components.

Weather Conditions: Your detector has been engineered with durability in mind. However, like any fine electronic equipment, your detector should be protected from excessively cold or hot weather. Freezing or excessive heat can damage the electronic components. The case is not waterproof, protect it from rain.

Additional Precautions: Avoid dropping your detector. Sharp blows to the loop should also be avoided.

Storage: Store the detector in a cool dry place not in a hot attic, etc...

The following service tips may help if trouble is encountered:

1. The detector will not operate (dead):

a) Check battery condition.

b) Check controls for intermittent operation.

c) Check the loop cable connection to case.

2. Erratic Operation:

a) Check battery condition.

b) Check to see that the loop cable is wrapped snugly around the rod and properly connected.

3. Oscillating or pulsing tone:

a) This effect can by caused by external electrical sources such as: power lines, television sets, CB radios, and for other nearby detectors.

4. The detector "drifts" or slowly changes in tone:

a) Sudden temperature changes can cause "drift" -- allow time to stabilize.

b) Apparent drift may be due to improper ground balancing, or use of the TR Disc. mode in mineralized areas.

c) component failure can cause rapid steady drift.

5. No sensitivity:

a) The GB Disc. & Target ID modes rely on motion to produce a sufficient signal for activating these circuits.

b) Mineralization can greatly reduce depth of the TR Disc. Mode.

c) Improper ground balancing.

d) Check battery condition.


In order to familiarize yourself with the operation of your detector and to be assured of all the modes of operation, the adjustment instructions may be carried out indoors if the following precautions are followed: Remove metal objects such as watches and rings and be sure that other large metal objects are at least several feet away so that there is no influences on the detector. Television, fluorescent lighting, microwave and other type of equipment of this nature can cause interference.


This TEKNETICS instrument is sealed at the factory to protect your warranty rights. Any evidence of tampering with the seals will automatically void any warranty rights you may have. Return the instrument to the factory or your nearest authorized service station.


Operating Frequency: 6592 Hz Crystal Controlled

Audio Frequency: 412 Hz

Weight: 4 lbs.. 12 oz.

Optimum Temperature Range: 33°-100°F

Optimum Humidity Range: 0%-75%

Power Requirements: 9v & 12v DC (Nominal)

Batteries: 14 individual NiCad Cells

Battery Life Expectancy: 7 to 10 hrs. continuous use (PER CHARGE)

Depth Capability: U.S. 25 Cent Piece 9" to 10" Your actual depth may vary somewhat as a result of ground conditions, length of time the object has been buried, and your skill.

Loop Diameter: 7 1/4 inch.

Loop Weight: 8 3/4 oz.

Loop Type: Bi-planar Concentric

Integrated Circuits: 32 I.C.'s

Special Feature: Meter Readout of depth of probable target. Also indicates battery condition.

Modes of Operation: G.B. Disc., G.B., G.B. Max, T.R. Disc.

TEKNETICS, INC. reserves the right to modify, improve, or otherwise change the design capabilities or specifications of its detectors without further notice.

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