Aka Sorex 7281 version 104 User Manual
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Selective Metal Detector «Sorex» 7281. Operating manual AKA LLC+7(495)623-4026 621-0481 http://aka.2000.ru [email protected] 11 «S» menu. To enter the «S» menu press and hold on the device panel. To browse its entries press the same button several times. To adjust parameters use buttons and . Press for exit or automatic exit 7 seconds after the end of the adjustment Menu entries. 1. General Boost 2. FGR Filter (false ground response) 3. HRN (hot rock neutralization) on/off 4. Storage off/auto/«3» 5. Short tone modulation (ST) on/off 6. Rate of AGBT 7. Economy mode (only for version 1.04) General Boost (Gen. Boost) of search coil signal. Option allows regulating search coil signal boost for the detection channel (Threshold tone) and identification channel (ST Sensitivity) simultaneously. Such setting may be used in extremely trashy areas, beaches etc, when there is no need in a great search depth, and distinction of objects located close to each other is more important. In most cases we recommend to set the boost value at 6. WARNING! The “Metal Trash” mode has its own separate General boost tuning. FGR Filter Option allows selecting false signal block-out level, signals caused by high conductivity of the ground (salty soil, sea beach etc). It is particularly important when using large-size ( (10’ and 12,5’x9,5’) search coil operating at high frequencies (14- 20 kHz), that comes from the specific character of the interaction of those search coils with the high-conductivity soils. it should be noted that the increase of filtering level results in search comfort increase, but it can also lead to missing of large and high-conductivity targets made of nonferrous metals. Filtering values should be selected empirically for specific search conditions, for this purpose it is desirable that they are kept to the minimum search comfort.
Selective Metal Detector «Sorex» 7281. Operating manual AKA LLC+7(495)623-4026 621-0481 http://aka.2000.ru [email protected] 12 HRN (Hot rock neutralization) on/off. This option allows turning on/off non-discrimination algorithm of hot rock signal neutralization. When it is turned on, most of the round-shaped rocks do not give identification signal, only the threshold tone with a light sound increase appears. The search becomes more comfortable in the area containing large quantities of such rocks, but it should be noted that in the uneven and broken ground, for instance in the rough plowland, this algorithm may detect some small targets in soil clods incorrectly and clip them out. In such case they would give the threshold tone signal only, sharper and shorter than rocks would. That is why in such places we recommend you to turn this algorithm off. Storage When the storage mode is off the display will show only the hodograph of the latest target identified by the device. Once the next target is identified, the previous hodograph is deleted. In the auto mode the display saves hodographs of the last three targets identified consequently. Whereby the hodograph of the last target is marked with the cut-in of two previous ones. And in the 3 mode the display also saves hodographs of last three targets identified by the device, but first and second hodograph do not cut-in with the hodograph of the last one. The auto or 3 storage mode is more informative than the off mode, and it allows to identify the target more accurately by means of several hodographs resulted from target scanning from different angles. Short tone modulation (ST) on/off. This option allows increasing sound indication capabilities, making the ST more informative in weak signal zones. Tone modulation is made by the width of tone burst depending on the object signal length and size of the object itself. The option contributes greatly to the distinctions between false responses of signal indication in the identification channel and signals from the objects. Rate AGBT [Off./1/2] With this setting you can turn on/off automatic tracing of ground balancing change and its correction by the device during operation. When this function is turned on, the device traces soil mineralization, search coil heating and cooling and other factors, influencing the accuracy of the device ground balancing, and it makes a correction allowing operator not to mind changes himself and perform the ground balancing procedure less frequently. This option is not recommended for use in trashy areas.
Selective Metal Detector «Sorex» 7281. Operating manual AKA LLC+7(495)623-4026 621-0481 http://aka.2000.ru [email protected] 13 Economy mode (only for version 1.04) The key feature of this mode is a shift to a low power consumption resulted from the reduction of ECC excitation current. Upon that, detectors runtime may reach 40 hours (with 2800 mAh battery). Besides, this mode allows performing ground balancing more accurately when working at the highly mineralized sea beaches. This mode is recommended for trashy areas where high sensitivity is no required. Warning! To turn the Economy mode on/off the fly during the search hold (for 1-2 seconds). The appropriate symbol is shown in the top right corner of the display when the Economy mode is on. Ground balancing Device ground balancing is the most important aspect of the device search settings. Incorrect balancing may reduce search capabilities of the device, causing unstable operation and false responses. Brief description of the procedure. Each object has its own shape, conductivity and magnetic compound, all of them are assumed to be VDI (Visual Digital Index). We remind that VDI is an angle preference, its number equals to the inclination of the signal vector (hodograph on the device display) from the vertical axis. The ground, depending on the mineralization level (presence of iron oxides), covers target signal with its own signal, changing its VDI till it converts small and deep targets, as well as large targets made of high conductivity metals (copper, silver, aluminum), into the iron. The accurate detector ground balancing in the search area is performed in order to reduce the ground influence to the minimum. Major balancing purposes: 1. To make the ground invisible for the device, i.e. avoid phantom signals from the ground with no targets in it. 2. Set up correct (standard) reference system for VDI. Accurately balanced device must cut-out ground signal mathematically and identify the target correctly getting joint signal from target and ground. It should be noted that during air tests the balanced device will keep making correction for the ground ... which is not available at the moment. During an air test it may lead to an invisible large aluminum or copper object (pan, 5 kopeks of Catherine II), if the ground has got too deep into plus. And if this too deep is too big, those targets may be detected as iron ... and the tester might get very frustrated. Or, to the contrary, it would decrease VDI of those targets, when balance gets too deep into minus, and sensitivity to them in the air goes up incorrectly ... resulting in unreasonable happiness and hopes of the tester. Memorize a simple formula: One degree of balance phase change gives VDI change for all targets by the same one degree to the change direction (+ or -). I.e. if you have 5 kopeks of Catherine II detected as iron in the air with VDI -86 instead of appropriate +82+84, then your device ground balance was set up by +10+12 degrees more than required for the air test. Ferrite piece balancing is required before the air test of the device. Put the device on the non-metal surface, turn on automatic ground balancing, count to three, and
Selective Metal Detector «Sorex» 7281. Operating manual AKA LLC+7(495)623-4026 621-0481 http://aka.2000.ru [email protected] 14 set a piece of ferrite to the centre of the search coil surface from the distance of 25-30 cm, finishing the balancing. Puzzled? Lets make it easier: Take a CD and pass it flatwise in front of the search coil. If the CD gives vertical hodograph and VDI within -1 0 +1, then the device is ready for the air tests. If VDI of the CD differs from these values then in the manual balancing mode (press twice ) correct the phase of the ground balancing by the difference level and to the required direction. Did the CD get VDI -1 0 +1? Congratulations, your device is ready for the air battle. Balancing Procedure. We would like to bring your attention to the automatic balancing procedure developed by experienced users. 1. Find a metal-free area. You can find it by the threshold tone response in RT-ST mode. On the unbalanced device there is a response to the pure ground, but the sound would be quiet and diffused, without strict localization, while the sound would be sharp and with strict increase above the metal object. Select an area with no localized sharp threshold tone increase swinging the search coil 5-10 cm to the left and to the right above the ground. If there is no localized sharp threshold tone increase, it is the area suitable for balancing. 2. Having found the metal-free area, raise the coil 30-40 cm above the ground, press , wait for 3 seconds, and move the coil to the ground smoothly but not slowly. Warning! Do not move the coil to the ground closer than 10% of the search coil diameter (for the searchcoilØ26 cm – 2-3 cm). It is related to the change in the pattern of the search coil physical interaction with the ground in the so-called Close Zone and it may impact balancing accuracy resulting in false responses in clear areas with high values of sensitivity during search. Short tone (thrum) notifies of the finished balancing. If there is no tone or it does not sound during lowering, but sounds when moving up, repeat the procedure with the same formula: 30-40 cm above the ground, 3 seconds, lower the coil to the ground. Follow the ground vector on the screen in the process. It should shape as a strait, slightly trembling line, on the horizontal axis of the scale. If it makes sharp angles or tears around the screen, it means that you are trying to balance on the metal object in the ground. In this case the device may balance but it would be incorrect for the operation, and you will notice it by numerous phantom signals from the ground. If it happened, just rebalance the device in the clear area. If you had balanced mistakenly in the area where the auto- tune system got frozen and could not rebalance (extraordinary but possible event), dont worry and turn off the device, turn it on holding + button, similar to the coil replacement procedure (see Search coil Replacement Procedure).
Selective Metal Detector «Sorex» 7281. Operating manual AKA LLC+7(495)623-4026 621-0481 http://aka.2000.ru [email protected] 15 After you have learned how to choose the balancing area, memorize the approximate balance digit in lower left corner of the screen in the balancing mode. Its sharp difference, especially in same weather conditions, during next balancing may be caused by metal in the ground, and you should change the ground balancing area for your device. If there were a metal object under the coil that had not allowed to make automatic balancing (objects with VDI close to 0; foil, for instance), then the device would give two consequent short tones, with a tonality similar to the iron signal in the search mode, and an exclamation mark in a triangle would popup on the screen with the sound. So, the balancing should be performed in another area. The digital value of the balance level (phase) pops up in lower left corner of the screen when balancing is over, this is the value the device will use to correct the VDI of the target, eliminating the ground influence. Digits, showing ground mineralization level will be displayed in the right corner, in accordance with the device scale. It is worth to mention that every device has a unique average angle of the ground balance phase and may also depend on the technical parameter spread of the search coil and ambient temperature. But, taking those values into account, don not forget that your device stays in the automatic balancing mode and it can elect to rebalance by ... a shovel, boots, your partner. That is why, if you want to review device screen and balance numbers after the automatic balancing, press the button one more time and enter the manual balancing mode to turn off the automatic mode. Letter M will replace letter А in lower right corner of the screen. To exit ground balancing press on the device panel. So, to enter manual balancing mode press buttons two times successively In this mode use buttons and to adjust balance to the required position, swing the coil vertically above the ground (move up 20-30 cm/ move down 3-5 cm), keeping track of the ground vector result getting in line with the horizontal axis of the scale, and device move-up/down buzz should disappear. Incorrect Ground Balance Vector (top picture). Correct Ground Balance Vector (bottom picture.) On irregular mineralization soils, for instance on a plowland, the device can not always be accurately balanced in the automatic mode, because when a vertical balancing is performed, there is one soil under the search coil (a clod or an air layer) and during scanning these pieces go one after another, sometimes it leads to phantom responses of the device identification channel. At the same time, ground phase digit in automatic balancing operation may differ by 3 degrees on the same place. If you face such problem, perform manual ground balancing in the following way:
Selective Metal Detector «Sorex» 7281. Operating manual AKA LLC+7(495)623-4026 621-0481 http://aka.2000.ru [email protected] 16 Find a clear area, 60 cm wide. Go to manual setup mode and making short horizontal search passes (but quicker) with a 50 cm amplitude, 3-5 cm above the ground, you will see a straight ground line on the screen (if it jerks, there is a metal). Upon that, if the balance is incorrect, you will hear a buzz from the ground and onscreen ground line wont be horizontal. Use buttons and to make it horizontal, the buzz will stop. Your device is balanced accurately. To increase the identification depth of large silver and copper coins (samovars, bowls and other large objects made of high conductivity metals) slightly, after the automatic balancing, it is possible, in the manual ground setting mode, to adjust the digit of the balance phase by 1-2 degrees to the minus values. Great adjustment (or drift) of the balance to the minus will lead to false responses with nonferrous signal, when bumping the coil over the ground and plants. Adjustment (or drift) of the ground balance to the plus values will lead to the reduction of the sensitivity to large copper coins (5 kopeks of Catherine II), up to their invisibility or even iron detection. If, by any reason, there is no clear area found, the balancing may be performed on a slice of excavated soil (1-1.5 kg), with all metal objects removed from it and having it in a plastic bag for the sake of convenience. After that fix the device and have its coil at the distance of 40-50 cm from the ground (put it on a bush, rest it on a tree with a coil on top), turn ground balancing pressing , count 1,2,3, and move the ground to the coil smoothly but not slowly from the 30-40 cm distance from the external or operating side. (similar to automatic balancing in the usual mode, but this time the soil has to be moved, not the coil) It is not recommended to put the device on the ground for such balancing. If could not find a clear area, the there is much iron in the ground. The iron may get into the field of the balanced device coil and the balance will fail. Warning! If the ground signal is weak (quartz sand) to the extent that the balancing program can not run, it is possible to balance the device using a ferrite piece or a red brick fragment automatically, putting them on the ground. Actually, an air test balance is suitable on such ground and even with balance adjustment by couple degrees to minus in order to increase sensitivity to large targets, if they are expected. Sharp temperature changes on the search coil may impact balancing accuracy, the balance may shift and become incorrect with such changes. That is why, if you take the device from a heated car and start working in a low temperature conditions (early spring, late fall), rebalance one or two times while the coil adapts to the ambient temperature. The t icon on the right corner of the screen will tell you that since the last balancing the temperature of the search coil has changed by the value (approximately 8° С) which requires ground rebalancing . In case of significant temperature drops (more than 15°С against normal +20°С) we recommend to perform electronic module and search coil adaptation procedure one more time (see Search coil Replacement). In this case the processor of your detector will
Selective Metal Detector «Sorex» 7281. Operating manual AKA LLC+7(495)623-4026 621-0481 http://aka.2000.ru [email protected] 17 choose the optimum frequency of the excitation current for these temperature conditions. Thereby all basic device parameters are sure to be kept, including absorbed current. In sea beach operations and other complicated soils with high conductivity we recommend to use the General Boost option for better balancing accuracy. Sometimes parameter decrease allows making balancing operation more accurate. Especially on sea beaches. Discrimination search mode setup Discrimination is device capability to respond to one type of objects, giving detection signal while ignoring other objects the operator is not interested in, for instance, nonferrous object signals only or large iron objects (helmets, kettles, buckets), ignoring small and medium iron trash (nails). This capability increases search comfort, but one should remember that a valuable object may be missed in this mode. Anyway, you get to choose. The discrimination range of your device is set up by the allowed width of the search sector (a VDI sector between left and right borders of the discriminator). When the discrimination mode is on your device will respond to objects with a VDI and hodograph located within the allowed response sector only. For example, sector covering almost all nonferrous objects and large-size iron objects (helmets, plow pieces, kettles etc), and ignoring small, medium and medium- large objects made of iron, will have the range of -30…+88. Sector with shotgun pellet, foil ... and small pieces of jewelry, crosses blocked, will have the range of +10…+88. Sector basically generated for the search for copper and silver coins of the Russian Empire ... and other valuable objects blocked (crosses, flakes, golden 5 and 10 rubles coins of Nicholas II and others) will have the range of +50...+86.
Selective Metal Detector «Sorex» 7281. Operating manual AKA LLC+7(495)623-4026 621-0481 http://aka.2000.ru [email protected] 18 Position of some metal targets on the VDI scale(for 7 kHz search coils). VDI Scale Objects From -90 to -86 hot rocks, incorrectly set up ground. From -86 to -70 small nails and other metal scrap. From -70 to -50 medium size wrought nails, small arrow heads. From -50 to -35 large wrought nails, medieval knives, flat arrow heads, horseshoes, locks and other fairly big iron objects. From -35 to -10 in this iron sector ferrum is hardly presented, and nonferrous objects masked by iron come across, small odd-shaped objects made of low-conductivity nonferrous alloys (bronze crosses, thin golden earrings, chains). Pay special attention to arrow-like and thin loop- like hodographs in this sector. From -10 to -10 foil, small bronze crosses, small shotgun pellets, small pieces of gold. From +10 to +30 pre-Peter Russian coins (flakes), sailor hat bottle caps; 1,2,10,15,20 kopeks USSR coins, minted before 1961. From +30 to +50 Golden chervonets of Nicholas II, screw plugs; USSR 3.5 kopeks, minted before 1961; Horde dirhams. From +50 to +70 pula, flake of the Copper Riot, small coins of the Russian Empire and early USSR, billon coins of the Russian Empire and early USSR, small silver coins of the Russian Empire of the 18th century and the beginning of the 19th century From +70 to +86 Large copper coins, silver rubles, as well as large flat or spherical iron objects (helmets, kettles, plows, axes etc). From +86 to +90 ground on the unbalanced device, hot rocks, as well as very deep large objects made of high conductivity metals (for instance, aluminum bowl, big silver salver). Hot rock is notable for stretched rubber signal, while signal from a metal object is usually concentrated in a small point. As we see, even in the nonferrous VDI sectors , trashy targets are found with valuable objects side by side. In other words, any valuable target may always have nonferrous trash with similar characteristics. Besides, do not forget that targets VDI is truthful in the reliable detection zone only and if there is no other metal object nearby. For example, iron underlaying golden chervonets of Nicholas II may take its VDI from standard +37 to plugs +18/+22. At full sensitivity limits in the ground it may suddenly sound like deep copper coin with VDI +85. It is a common feature not only for your device, but for all devices of this type. So, any cut-off and no-dig of the potential trash is a compromise between comfort and loss of valuable catch. You never know, may be that hundredth kind of plug, you did not dig after 99 of dug-up ones, was a rare princedom age coin. Warning! When using search coils with a low frequency of excitation current VDI parameters will have lower levels. And vice versa, higher frequency gives higher VDI.
Selective Metal Detector «Sorex» 7281. Operating manual AKA LLC+7(495)623-4026 621-0481 http://aka.2000.ru [email protected] 19 Discrimination Sector Setup. To setup required discrimination sector, press several times, select entry setup left discriminator border. You will see a VDI digit in the square frame above the left border of the discrimination sector. Use buttons and to change this number, moving the border to the left, increasing range of targets accepted, or to the right, decreasing the range. Targets with VDI located on the scale to the left from the discriminator border, will be cut-out. Press one more time to get to the setup right discriminator border. You will see a VDI digit in the square frame above the right border of the discrimination sector. Use buttons and , to change this number, moving the border to the right, increasing range of targets accepted, or to the left, decreasing the range. Targets with VDI located on the scale to the right from the discriminator border, will be cut-out. To exit discriminator setup press , or automatic exit 7 seconds after the end of the last setup input. Warning! We recommend to setup VDI value of the left discriminator border equal to the low tone border (LTB). “All metals” search mode In this mode the device responds to all objects, either iron or nonferrous, with the tone corresponding to objects VDI. The advantage of this mode is in high descriptiveness and informativity, giving an insight into quantities and structure of the ground metal. Apparent disadvantage is a high sound overflow, especially in trashy areas. Your device allows reducing sound overflow using iron object sound volume decrease (setup Sound Volume Fe). In this mode the device also responds to some so-called hot rocks of the prolate form. SOREX 7281 identifies most of these rocks and does not give sound response to them. If you are not interested in such signals, and they even disturb you, use discrimination mode, in practice it corresponds to the all metals mode. Setup left and right discrimination border to -86 and +86 respectively.
Selective Metal Detector «Sorex» 7281. Operating manual AKA LLC+7(495)623-4026 621-0481 http://aka.2000.ru [email protected] 20 Static mode (Pin-Point) This mode is used basically as a secondary mode to clarify target location in the ground. After target detection in dynamic mode (primary search mode), put the coil slightly aside from the assumed target location and press . Warning! Avoid turning this mode on in the zone of target sensitivity (put the coil rather far aside). Then smoothly pass it above the detected target, keeping constant distance from the ground. Sound signal volume and frequency will increase upon approaching the target, decrease upon moving away. Frequency and volume peak will be noticed at the centre of the target respectively. To finish centre clarification make two perpendicular passes. Signal peak cross, right under the centre of the coil is a target centre. At the same time, target centre clarification may be visually controlled on the screen of your device. Onscreen scale cells will be filled when approaching the target centre and brighten when moving away from the centre. Target centre corresponds to the fully filled onscreen scale. Use buttons and to adjust static mode sensitivity. If the signal is too strong and continuous, the target is large and relatively close to the surface. Raise the coil to the level where the target is less responsive and you will be able to detect target contour in the ground by crossing passes. To exit the mode press one more time Search coil replacement. Warning! Prior to coil replacement find a clear area, because ground balancing will be required after replacement. Or, if there is no clear area detected, get a piece of ferrite or a piece of red brick. Connect the required coil to the shaft, wind the cable around it and connect it to the unit slot. Hold the device at the distance of one meter between the coil and the ground and away from metal objects, turn on the device, holding button on the device panel. Hold the button until device stops playing the melody and the onscreen short-time search coil operating frequency indication appears.