No 4c Mine Detector (Part 2)

Following on from Friday’s post, today we look in detail at the mine detector itself:

The detector consists of three parts, the head, the handle and the amplifier unit. We go back to the instruction manual for more information on each component:

The Search Head

The search head is a flat container in which the search coils are sealed.

As can be seen, my example is missing the trimming unit cover. The description of the head in the manual is pretty scant, presumably to keep the average soldier from messing about with it- there were no user serviceable parts so there was no need for the average soldier to understand what was inside the head.

The Telescopic Pole

This consists of four metal sections so graded in diameter that they may be collapsed into one section, which when pulled out forms a pole approximately four feet in length. The narrow section of the pole fits over a handle attached to the search head and is securely held in position by means of a clamping nut which is permanently attached to the narrowest section of the pole. The largest section of the pole has a collapsible hand grip attached, also a padded forearm rest. In the operating position the forearm is strapped to this rest by means of a captive webbing strap.

The Amplifier Unit

The amplifier unit consists of a die cast metal case having two compartments. The first compartment which is hermetically sealed and desiccated, houses the printed circuit five transistor R.C. coupled amplifier. The second compartment, entry at the rear of the case, houses the 9 volt battery which supplies power to the amplifier. This compartment is rendered splash proof by a specially designed cover, or bung. This bung consists of two metal plates between which two rubber gaskets are placed. The act of tightening a knurled nut after the bung has been placed in position causes the gaskets to be compressed between the metal plates so that the rubber flows out, thus providing a good splash proof seal between the bung and the sides of the compartments.

The battery (Battery Dry 9 Volts YC. 02272) is fitted with press stud terminals and for normal use is fastened by these to mating terminals on a terminal block attached to the inner face of the bung. For arctic use, i.e. below 32 degrees F, to ensure the efficiency of the battery, an extension cable is provided which enables the battery to be carried inside the operator’s clothing. When this extension cable is used, the two metal plates and gaskets on the bung are so positioned that cut-outs on their peripheries are aligned, giving entry for the cable to the battery compartment…

All controls are grouped on a panel at one end of the unit, termed the control panel.

The amplifier unit is equipped with hooks which enable it to be attached to the user’s belt, the most convenient carrying position is at the left side rear, with he control panel facing downwards, in such a position that when controlling the sweep with the right hand, the user can easily tune the REGEN control or operate the PRESS TEST button, with the left hand.

The manual also gave some advice on how to use the mine detector, as well as diagrams of two different ways of detecting mines:

Searching for Mines

Position the search head to within 3 to 6 inches of the ground and parallel to it.

Sweep from side to side in wide arcs, using the free arm to help support the weight of the detector, after each sweep move forward a short distance, approximately 10 inches, ensuring that all the ground to be searched is covered by the search head.

The proximity of a metallic mine, or similar body, is indicated by a distinct loud note in the headset whether set up NORM or set up PAVE is in use.

Small objects and also deeply buried objects will not give a strong signal immediately, therefore searching must be slow enough for weak signals to “build up” before the search head is moved out of range. The search head must also be held as close to the ground as possible.

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