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Radio Shack

63-3003 Micronta 4003

Page created December, 2010

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This model is a step up from the 63-3001. It might be interesting to check one out sometime if I get the chance. As you can tell by the updated packagng, this unit was offered for a number of years.

VLF Discriminator Metal Detector 630-3003

Micronta 4003

Weight: 3 lbs

Type: VLF

Operating Frequency: 15 kHz +/- 2 kHz

Distance Range:

Coins: 8"

Large Objects: up to 5'

Search Coil: 8"

Audio: Speaker/1/4" Earphone Jack

Batteries: (three) 9 VDC

Battery Life: approx. 30 Hrs

The steps in this section explain each control on the control housing and

handle, and how to use your metal detector. Take a moment to become

familiar with the position and use of the controls before using the metal



The view meter is located at the top of the control housing and measures

battery power, determines the quality of hidden metal, and helps you tune

the detector.

Turning On the Detector

Hold the detector in a position comfortable for you, then turn it on by

rotating VOLUME two-thirds clockwise. Set TEST to NOR to detect.

Adjusting the Controls in the Field

The tuning skills you will learn while preparing the detector will be put

to good use during your actual search. You will know how each control

works so you can fine-tune the detector quickly.

If you wish to test the accuracy of your tuning at your current location

in the field, take a few samples of different kinds of metal with you.

Note that some metals, when left exposed to the elements, become

corroded; so, it is always wise to carry along a piece of corroded metal.


Setting TUNE

The Radio Shack VLF Discriminator Metal Detector distinguishes between

ferrous and non-ferrous metals. When the detector senses a metallic

object, one of two reactions occurs - the sound and meter reading

increase or decrease. The result depends upon the type of metallic

material, ferrous or non-ferrous. Ferrous metals contain iron. Gold

silver, copper, platinum, aluminum, lead, zinc, etc. are examples of

non-ferrous metals.

TUNE fine-tunes the balance between the detector's receiver and

transmitter circuitry.

Follow these steps to set TUNE.

1. Rotate VOLUME two-thirds clockwise.

2. Set MODE to VLF.

3. Set TEST to NOR.

4. Set the remaining controls to mid-range.

5. Hold the search coil up in the air, press and hold down Auto-Tune,

and slowly turn TUNE. The pointer swings back and forth and the

detector sounds a tone. Turn TUNE until the pointer rests at or

near the center. Release Auto-Tune.

Note: Press Auto-Tune during operation to automatically return the

pointer to the center.

Setting MODE

Set MODE to VLF when you use GROUND (See "Setting GROUND). Set MODE to

TR1 or TR2 when you use DISCRIMINATOR (See "Setting DISCRIMINATOR)".

Using GROUND helps tune out false signals from mineralized soil.

DISCRIMINATOR distinguishes between NON-FERROUS and FERROUS objects.


To adjust the search coil's ability to detect objects at different

depths in the soil, rotate SENSITIVITY from MIN to MAX. For maximum

performance, set SENSITIVITY as high as possible. If the detector

makes a "Chattering noise, decrease SENSITIVITY until the "Chatter"


Setting GROUND

GROUND tunes out false signals from mineralized soil.

Follow these steps to set GROUND.

1. Set MODE to VLF and lower the search coil to 1/2- to 2 - inches above

the ground.

2. If the pointer swings to the left, turn GROUND to the right.

3. Raise the search coil and press Auto-Tune. The pointer returns to

the center.

4. Repeat Steps 1-3 until there is a very small variation in the meter

reading each time you lower the search coil to the ground.


Setting GROUND takes a little time, but is critical for accurate


After you set GROUND, do not reset it until you use the detector at

a different site.


DISCRIMINATOR determines whether the hidden metal is NON-FERROUS or


Before you set DISCRIMINATOR, you must set MODE. Set MODE to TR1 to

detect extreme differences in metals, such as between iron and gold. Set

MODE to TR2 to detect even greater distinction between metals.

Set DISCRIMINATOR to mid-range. While you detect, adjust DISCRIMINATOR

to the best position. The difference between iron and gold shows on the

meter (iron in the ferrous section, gold in the non-ferrous section). As

you set DISCRIMINATOR higher, the detector becomes more sensitive to the

differences between aluminum and gold, but some small pieces of valuable

jewelry, such as small rings, may be over-looked. Therefore, coin

collectors do not usually set DISCRIMINATOR higher.

Also, it first rejects small pieces of silver paper, then thick foil, and

finally metal objects like pull tabs from aluminum cans.


Each time you use the detector, you must adjust DISCRIMINATOR. Each

expedition presents new challenges.

Press Auto-Tune during operation to automatically return the pointer

to the center.

Fine-Tuning the Controls

Set these controls:

1. TEST to NOR

2. MODE to VLF

Set the remaining controls to mid range.

When you detect metal, switch MODE between TR1 and TR2 to determine the

quality of metal. Adjust all remaining controls to their desired

positions. (See "Tuning the Detector.")


Keep the search coil in a consultant parallel position to the ground

throughout the sweep. Move the search coil slowly from side to side,

covering about a 3-foot area, overlapping each sweep. The threshold tone

should peak as you pass the target center. (Hurrying will cause you to

miss targets.)

Note: The search coil will not detect without motion.

Be careful not to swing the search coil upward at the end of each sweep.

The swing up can cause the detector to emit false signals. Keep the

search coil parallel to the ground at all times but don't touch the

ground. Hitting the ground may cause a false signal.


No detector is 100 percent accurate. Various conditions and objects may

adversely influence metal detection. Its reaction depends on a number of


The angle at which the object rests in the ground

The depth of the object

The amount of iron in the object

The size of the object

To pinpoint an object, the second time, go at right angles to the first

time, making an "X" pattern.

Note: The target will be directly below the "X" at the point of the

loudest response.

This allows you to detect some targets that were hidden the first time

due to the sweep direction. If trash in an area is so heavy that you

get false signals, slow your sweep speed and use shorter sweeps.


A good detection has a consistent rise and drop of threshold tone.

A poor detection has irregular highs and lows in threshold tones.

If the metal is in the shape of a circle, opposite reactions may


A good target response repeats as you swing the search coil over

the suspected target. Trash-induced signals tend to not repeat.

Recently buried coins might not respond the same as coins buried

for a long period of time.

Some nails, nuts, bolts, and other iron objects (such as old bottle

caps) oxidize and create a halo effect around these objects.

A halo effect is caused by a mixture of natural elements in the ground

and the oxidization created by different metals. Because of the metal

mixtures, target signals may not be in a "fixed" position. This effect

makes these objects very hard to reject. (See "Fine Tuning the



The threshold tone may vary slightly while you search due to soil

changes. This does not usually affect the sensitivity of the unit and

should not require further adjustment.

If the threshold tone changes significantly, you might need to readjust

GROUND. Sometimes the change in threshold tone is due to reasons other

than ground conditions and can be easily corrected by a simple procedure.

Raise the search coil one foot from the ground and push Auto-Tune.

Lower the search coil to the ground again. If this does not correct the

problem, repeat the full procedure to set GROUND. (See "Setting

GROUND.") If you continue to have problems, contact your local Radio

Shack store for assistance.


Follow these steps to adjust the metal detector's stem before use.

1. Hold the detector with the search coil level to the ground.

Note: The search coil should be approximately 1/2 to 2 inches above

the ground.

2. Turn the stem's lock nut clockwise until it loosens.

3. Extend the stem to the desired length.

4. Turn the stem's lock nut counterclockwise to lock it in place.

5. Wind the search coil cable around the stem. Be sure to provide

enough slack in the cable to accommodate angle adjustments.

6. Place the search coil plug into the plug connection at the base of

the control housing. Be sure the holes and pins line up correctly.

Push the plug in until it is secure.

Caution: Do not force the plug or you may damage it.

Note: When disassembly is required, remove the plug by pulling at the

connection point.


Hold the search coil level with the ground and loosen the knob at the

search coils end. Adjust the search coil and tighten the knob to keep

the search coil from rotating or wobbling.

You can put the search coil in fresh or saltwater up to 6" from the

control housing. Rinse it with fresh water afterwards to prevent



The meter is used for three functions: testing batteries, determining

quality of hidden metal, and tuning the detector.

With the power off, use a thin-blade screwdriver to turn the alignment

control until the pointer lines up with 0 on the scale.

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