White’s Electronics TDI BeachHunter Owner's Manual

Owner’s Manual

TDI

BeachHunter

White’s Electronics, Inc.

Sweet Home, Oregon USA

Building the World’s Finest

metal detectors for over 60 years.

2

CONTENTS

Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Batteries and Charger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

QuickStart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Principles of Pulse Induction . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Controls

Threshold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Power/gain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Pulse Delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Target Conductivity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Ground Balance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

TDI In Depth

Ground Balancing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Audio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Pulse Delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Dual-eld coil. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Dealing with Noise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Specications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Code of Ethics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Back Cover

3

Cam lock

Clevis

Rubber washers (2), ber bolt

Search coil

Lower rod

Arm cup

Battery door

1. Remove all parts from the shipping carton and check assembly

diagram to ensure all parts are present.

2. Install black rubber washers on ber clevis/lower rod, insert

clevis lower rod onto loop ears. Use only nonmetallic wash-

ers, ber bolt, and ber thumb nut to secure loop/search coil
to clevis/lower ber rod.

3. Unlock middle rod cam-lock and insert clevis/lower rod into

middle rod so that stainless steel spring clip buttons line up
and lock into one of the adjustment holes in the rod. Turn
cam-lock to secure. The second or third adjustment holes are
suitable for average sized adults.

4. Wind the loop cable around the rod assembly, rst revolution

over the top of the rod, all the way to the top of the middle
rod, about ve revolutions. Use the black cable retainers, one
near the loop, and one near the top of the middle rod, to hold

the loop cable in place. Make sure the cable is wrapped all
the way to the front of the control box.

5. Grip the instrument by the handle, with your arm in the

elbow cup with strap and sweep the loop/search coil over

Assembly

4

the oor. If the instrument t feels uncomfortable, readjust

clevis/lower rod length with spring clip button and cam-lock

so that search coil can be held near the oor without stooping

over.

6. Remove the protective paper from the two black arm cup

foam pads. Carefully align pads on the inside of the elbow

cup, one on each side of the center rod, and press rmly into

place.

7. Adjust the elbow cup strap so that it is loose enough for you to

slide your arm in and out without loosening each time you
want to set the detector down. The elbow cup strap provides

extra leverage and control. However, some prefer not to use

it.

8. Install the battery pack; see the next section for information

on batteries and charging.

5

Batteries and Charger

The TDI-BH includes a rechargeable NiMH battery pack as

the primary power source, and a standard alkaline battery pack
as a backup. Fully charged, they supply a nominal 12 volts (the

NiMH may be slightly less) and will power the TDI-BH for
about 4-6 hours. The TDI will operate until the batteries drop

to about 8.5 volts, at which point the low battery LED will turn

on.

A drop-in charging cradle (Part Number 509-0036) is used

for recharging the NiMH battery. With the wall transformer

connected to the cradle and plugged into a wall socket, simply
drop the NiMH pack into the cradle. An LED indicates the
status of the charge cycle; when the LED turns off, the charge

cycle is complete and the charger will automatically switch to
a trickle mode. A typical recharge time of a depleted NiMH
pack is 1-2 hours. It is normal for NiMH batteries in storage to
slowly lose their charge over time; be sure to top off them off
before going out.

The alkaline pack is designed so that it cannot be used with

the charger, and trying to recharge alkaline batteries can cause

them to burst and leak. Individual NiMH batteries can be used
in the alkaline tray; it is recommended that the batteries be re­moved and charged using the manufacturer’s charging system.

6

QuickStart

1. Ensure machine is adjusted for comfortable t and use.

2. Set the Frequency offset to the midpoint.

3. Set the Ground Balance to 6-8.

4. Turn on the power and adjust the Gain to “2.”

5. Adjust the Threshold and Volume to achieve a faint back

ground hum.

6. With the coil on the ground (no motion) increase the Gain

until the audio begins to chatter. Back off slightly for a
reasonably smooth threshold.

7. Optional: adjust the Frequency offset to minimize the amount

of chatter.

8. Using a spot free of targets, bob the coil up & down and

adjust the Ground Balance control to minimize the audio
response.

9. In heavy salt or mineralization it may be necessary to adjust
the Pulse Delay to around 15-20us.

7

TX

RX

Exponential decay

No target

Raw Response

The Pulse Delay control, which determines the point where

the decay is sampled, can be used to eliminate low conductive

targets such as thin foil. Further increasing the delay can knock

The use of high-powered impulses results in better ground

penetration than VLF, especially in highly mineralized soil. This

makes the PI detector the best choice for certain kinds of hunting

in bad ground where many VLFs simply won’t work.

There is no traditional discriminator in PI detectors, although

there is some ability to discern certain types of metals. The decay
response varies with target conductivity (plus other characteris­tics) so that low conductive targets have a fast decay and high
conductive targets have a slow decay:

Low-conductive target, fast decay

High-conductive target, long
decay

Principles of Pulse Induction

Pulse induction (PI) detectors are very different from tradi­tional induction-balance (VLF) designs. Instead of transmitting
a continuous-wave magnetic eld, the PI detector periodically

transmits brief impulses of magnetic energy. The PI receiver
then looks at the impulse decay for target (and ground) infor­mation.

Pulse Rate

8

out other minor trash targets at the expense of eliminating po-

tentially good targets such as jewelry, but this method is very

limited in the range of trash targets that are rejected.

Furthermore, the ground balancing method used by TDI has

a side affect with target responses. Target conductivities below
the ground balance point produce a positive response for which
TDI assigns a high tone. These targets are generally low con-

ductive such as small nuggets, jewelry, and small iron. Target

conductivities above the ground balance point produce a nega­tive response for which TDI assigns a low tone. These targets are

generally high conductive such as silver coins, relics, and large

iron.

Low-conductive target

No target

High-conductive target

Ground balance point

Differential Response

The Target Conductivity switch can be used to eliminate either

class of targets, or to accept them all. Care should be used with

this feature as it is not always obvious as to how a target might
respond. Testing with known targets is the best way to learn the
responses.