Article in the 2009 Year Book and March 2009 Australian Gold, Gem & Treasure magazine.

by ADRIAN ROSS
   

Well at long last after 2 years of procrastinating and ear-bashing Phil Stearnes of the Gold Mining Centre SA in regards to the Infinium LS I finally decided that it was time for a new detector for my beach and gold metal detecting.

            There were several detectors on my hit list: The Tesoro Sand Shark, Whites Pi pro, Garrett Infinium LS, Minelab Explorer and Excalibur, a minelab PI and a couple of UK PI units. The Infinium is what I settled on my decision was based on Capability, versatility, performance and value for money.

            My detecting these days is mostly beach work with the odd trip or two to the Victorian gold fields, so with that in mind I decided that I did not need sophisticated discrimination because using disc in the gold fields will loose gold and on the beach, (which is relatively free from trash) you will miss small gold chains and rings etc plus for beach work I wanted it to be Water proof; this narrowed my search down to an all powerful Water proof All Metal Detector that could work extremely well at the beach and excel in the highly iron mineralised Australian gold fields. The Infinium is the only detector I found that met all those requirements. It can be used when scuba diving in fresh or salt water to 200 feet, it can be used for coin and relic hunting and it excels at gold detecting in any ground conditions that you can subject it to. It is without question a go anywhere do everything metal detector except it cannot be used for ground mineral surveys like Two Box detectors.

      Anyway, to cut a long story slightly shorter, I now have an Infinium LS and have spent the past 6 months checking it out.

The detector arrived with a 10x14 inch DD coil, headphones, an in car battery pack re charger, a 240 vac charger, an instruction video, carry pack for belt mounting the control box and an operators manual.

My first impressions were that the control box was heavy and of solid construction, which of course it had to be because the Infinium is water proof to 200 feet (62 metres Approx). The 10x14 DD coil is heavy, waterproof and can be used for all types of detecting. Other coils available are: 5x10 inch DD, 3 x7 inch DD, 10x14inch Mono and an 8-inch Mono.

            The Infinium is a Pulse Induction All Metal detector with Discrimination Auto Tune and 3 ground tracking modes: Fixed, Slow and Fast Auto Ground Tracking. It has an Iron Check system that will identify Iron at pretty much whatever depth a target is detected. There is a frequency adjustment that will reduce or tune out completely any external electrical interference. The detector has been designed to function in extremely high mineralisation and it’s prime function is for gold detecting in these conditions.

            The Infinium signals the presence of metal by emitting either a drawn out high tone followed by a low tone or a drawn out low tone followed by a high tone or by slight variations in the threshold tone.

The manual is brief and gives the impression that the Infinium is a” Turn On and Go” Machine. The video is equally brief and explains the basic functions quite well, which includes Switch On, Battery Check, Threshold Adjust, Ground Balancing, Discrimination and Frequency Adjust. and Iron Check. I was to discover over the next few months that there are many other operational characteristics of the Infinium that are not mentioned in the instruction manual

I assembled the detector and went into the back yard to try it out and I soon discovered what most pulse induction detectorists know and that is that PIs are very sensitive to electrical interference from power lines, phone lines, radio transmitters and just about anything else that generates a changing electromagnetic field.

I switched the machine on and heard 4 beeps in the headphones that indicated that the batteries were fully charged (three beeps partially discharged, two beeps almost flat with maybe one to two hours detecting left, one beep, is time to change the batteries)

 This first position is also Slow Tracking; I ground balanced in slow tracking by bobbing the coil up and down several times a few inches above the ground until the threshold became quieter as per the instructions and then selected the lock position which prevents the ground balance from changing from the locked setting.

            At this point I could hear many and varied HI/LO and LO/HI tones with the coil resting on the ground, which signified electrical interference. I adjusted the frequency adjust as per the operating instructions but could not completely eliminate the interference which I assumed was being caused by local phone lines, power lines and a nearby radar transmitter that fires cancer causing radiation through my house at one second intervals; I continued to scan my back yard where I have various metal objects buried and the Infinium located all of these items very easily; These items are buried at 20cm and all gave a distinct signal that I was able to hear through  all the electrical interference but the confused tone changes was making pinpointing difficult. And I quickly realised that this was a very sensitive and powerful detector and to give it a fair test I would have to get away from the severe elec interference, so I went to a local picnic ground with sandy river beaches and some rocky areas where the rocks were fairly hot. I also brought along for comparison one of my way better than average vlf machines. At switch on the Infiniums threshold was rock steady. When I lowered the coil to the ground to check the ground balance the threshold did not change and I did not have to ground balance. I located a few coins and many bobby pins; I then moved over to the rocky area where the hot rocks were a problem for all of my other vlf detectors and Yahoo, the Infinium breezed over these rocks like they did not exist, I thought I would have to at least re ground balance a bit but it wasn’t necessary. This was too good to be true so I placed an Aussie 2 dollar coin under what I knew was a hot rock (from experience with another detector) about 20+ cm in diameter and re scanned and the infinium gave a distinct warbly hi/lo lo/hi tone which as it turns out is normal for the Infinium from an Aussie 2 dollar coin; My vlf could not locate the coin in discriminate mode but could in All Metal after the machine was ground balanced over nearby rocks (I will talk about the various tones that the Infinium produces later on.

            So far so good but I was now beginning to notice the weight of the big 10x14DD; The infinium has four positions that the control box can be mounted in; Above the stem near the hand grip, beneath the elbow cuff, hip or chest mounted, I had it above the stem and I was finding it to be awkward and out of balance so I later moved it to beneath the cuff and in this position the machine is balanced quite OK and that is where I have left it.

            A fresh water beach is no test for any metal detector; even a supermarket special will work in those ground conditions so the following weekend I headed off to a beach on the South Coast.

I went straight to the water line and attempted to ground balance as per the instructions by bobbing the coil up and down several times from 2 to 6 inches above the sand but I was not achieving good ground balance, I rested the coil motionless on the sand and listened to the threshold, it was wavering and giving quiet hi/lo and lo/ hi tones which I thought might be electrical interference so I carried out the frequency adjust procedure and this is when I discovered TIP #1: The ground tracking must be in the LOCK position before freq adjusting otherwise the Infinium will try to ground track the electrical interference and TIP #2; The discriminate control must be returned zero before ground balancing with the tracking selector in either fast or slow. After doing this I achieved good ground balance but there was still some tones at the end of each swing, out came the book again where it suggested in the event of imperfect ground balance to increase the discrimination control in small increments but to not more than number 3; At a setting of 2 the infiniums threshold was nice and even and I did not have to adjust the ground balance again over a period of 3 hours detecting.

It is because the Infinium is set up to ignore the extreme mineralisation of the gold fields that it does not have a preset level of salt discrimination to enable it to work on saltwater beaches like normal pulse induction detectors, so to offset this, all you have to do is to increase the discrimination control up slightly to around the 1 to 3 setting; If it is set higher, sensitivity to gold will be reduced.

Throughout the day I found several Aussie coins, bottle screw caps and heaps of bobby pins, plus pull-tabs and fishhooks; Most of which were found at significant depth. I found 5 cent coins at better than 15 inches, 20ct at somewhere between 40 and 45cm, bobby pins at bloody near 2 foot, one aluminium drink can at 2 foot +. All of the deep targets gave a quiet but clear h/lo or lo/hi tone and all were in the wet sand, I am certain that if these items had been a few inches deeper the infinium would still have responded.

When I moved into the water to knee deep level the threshold began to waver slightly as the waves moved up and down the stem but not enough to break into a tone change, I did not feel the need to re ground balance. I remained in the water long enough to satisfy myself that the machine was working well, found two sinkers at about 8 inches and then called it quits for the day; At this time of the year the water is very cold.

I had tried the Reverse Discrimination on most of the beach signals and found it to work well and it does discriminate to the depth of the target but like most discriminators it is not infallible; The manual states that high conductivity metals will produce a Low tone followed by a High tone and poor conductors Produce a High tone followed by a Low tone; I found that in most cases this is true however some rusty wire and tins will give a HI/LO tone as well as many bottle caps that have a brassy coloured plating. And bobby pins are a real pain in the butt. (All Pi detectors give a strong signal to iron based metals) but as I said earlier, I will elaborate on discrimination and response to various target types later..

In the depth stakes the Infinium with the 10x14 DD coil was definitely out performing my Sovereign XS beach detector fitted with the 15 inch Wot coil and this detector is no slouch; This is what I was hoping for and it, was handling the beach conditions very very well when you consider that this detector is set up primarily for extreme mineralised gold field conditions.

During this experimental time one thing had become very apparent and that is that the Infinium must be used with a very slow sweep speed of around ½ to no more than 2 feet per second otherwise you will miss a lot of targets

The following weekend I decided to try the Infinium on an extreme iron mineralised hill not far out of Canberra; I have tested all of my detectors on this hill about 15 years ago and none, other than my Lobo Super Traq could even get close to handling the severe ground conditions.

When I arrived there that hill looked a hell of a lot higher than it did 15 years ago, and it was going to be a hot day.

Because the ground was very rocky and rough I decided to use the 5 x 10 DD.

Three quarters of the way up where the ground consisted of red iron oxide dirt, shards of ironstone gravel and ironstone rocks ranging in size from pebbles to steam engine size is where I decided to test the Infinium.

I turned the detector on and attempted to ground balance in fast track over the red gravel and some large ironstone rocks; I managed to get a fairly stable threshold. (Took a couple of minutes). This was a first because I had not been able to get my other detectors within a bull’s roar of this ground before they would overload.

I selected the ground track lock position and began scanning, the threshold remained reasonably smooth, only increasing slightly as the 5x10 DD was within 5cm of the surface; I was actually able to place the coil on the ground and still maintain a pretty stable threshold, you have to remember that this ground is almost all iron ore in one form or another. In fast and slow track the threshold also stayed very steady and so I left the selector in the lock position

I placed a 2.5 gm solid gold nugget under an ironstone slab that was about one metre wide and 4 to 5 cm thick by God knows how far into the hill it went and scanned over the ground while moving slowly towards the slab from about 4 metres away; The threshold remained quite stable only increasing and decreasing in volume very slightly;

 As the coil passed over the slab I got a nice hi/lo tone, not loud but easily heard; In the iron check mode there was almost no signal which indicated a possible good target, but when I scraped the coil across the slab in iron check I heard a very weak hi/lo tone, this also indicates a likely good target possibly gold.

I was impressed; in these ground conditions I found it difficult to believe that this detector was penetrating the ironstone like it didn’t exist.

It was now mid afternoon and beginning to get hot so it was time to go and I doubt that I will come back here again, I think I am getting to old for this lark where you have to be a mountain goat to get to places like this; I came home feeling very satisfied (and a bit surprised) knowing that the Infinium could find gold in such extreme ground conditions.

Ground Balance.

Ground balancing the Infinium is basically very simple

First turn the unit on and wait a couple of minutes for the machine to stabilize before making any adjustments, then with the discrimination set to zero and the threshold at a level that is comfortable, (preferably just audible) turn the ground track to the slow or fast position and bob the coil up and down several times from ground level to around 6 inches above the ground; if the tone does not change during this procedure then the unit is balanced for that particular area. Do this until the threshold tone becomes quiet and even and then select the lock position. This procedure is the same for saltwater beaches as it is for the highly mineralised goldfields. The only difference you might find is that a small amount of discrimination may be needed at the beach in order to cancel out the effects of the salt; (although I did find in one particular iron mineralised area that a disc setting of 2 helped quiet some of the noise down even further) This is because the Infinium is set up to run smooth in ironstone country with the discrimination control set to zero.

Only adjust the discrimination after the unit has been ground balanced with the disc set at zero, do-not attempt to ground balance with the discrimination in any other position.

 There are some gold field conditions where some alkali salts are present when a small amount of disc may be needed. It is not advisable to set the disc control above 3 because at this setting small gold items will be discriminated out. If there is hi/lo tones at the beginning and end of the sweep then the ground balance is still out of adjustment so repeat the GB procedure; or try selecting fast or slow tracking. You will know if the GB is out a bit if by resting the coil on the ground for a few seconds and then raising it quickly above the ground about six inches produces a threshold tone change. However you will find that the Infinium can be ground balanced in all ground conditions that you will encounter in the gold fields and this is where this detector excels.

Frequency adjustment.

The purpose of the frequency adjust is to help eliminate the effects of external electrical interference from power lines and other metal detectors. I found that eliminating sporadic Interference from radar, phone and fax lines, aircraft and ship to shore radio transitions is difficult but the effects of these can be reduced

 Selecting a different frequency position will not make the Infinium any more or less sensitive to hot rocks or ground mineralisation.

I found that trying to use the Infinium in city areas where electrical interference is everywhere was difficult and the only advise I can give here is that if you want to use this detector in urban areas then use a small coil like the 5x10 or 3x7 DD because they are less sensitive to interference than the big Mono or DD coil

The operator’s manual gives a good enough explanation of how to adjust the frequency

Discrimination

When I first purchased the Infinium I must admit that I was not very interested in the

Discrimination aspects, I was only interested in its ability to penetrate deep into any type of ground and respond to very small and very large targets, but having said that. I find the normal and reverse discrimination tones to be quite useful.

            The detector produces a Low tone followed by a High tone for High conductive metal and a High tone followed by a Low tone for low conductive metal and depending on the type and size of metal detected, these tones can change from one to the other depending on the setting of the discrimination dial which is how the reverse discrimination is used to separate gold from iron.

Like any other discrimination control the Infinium will begin to reject small items as the disc is advanced above zero and larger items will be rejected as the control approaches the top end its range however, it is the tone change that makes this discriminator interesting and a bit of time spent in learning how the detector responds to different metals can de beneficial.

The discrimination control is normally used to get a rough idea of what type of metal you may have detected when searching the beaches or parks etc.

When you get a signal, keep scanning the target and gradually turn the discrimination control up until the signal tone goes quiet or just changes from HI/LO to LO/HI or visa versa and note the position of the discrimination control at this point.

By experimenting with various targets both in the ground and as a bench test and by learning the signal drop out or tone change point of your favourite target types you can now use the disc control to help identify these targets.

Identifying gold from iron and Reverse Discrimination.

Reverse discrimination is achieved by rotating the discrimination control all the way around to the Iron Check position and noting the effect this has on the target signal.

            I find that the best way to identify gold from iron in gold field conditions is to dig all signals that are HI/LO or LO/HI in normal mode which remain or change to HI/LO in reverse disc at reduced signal level or that disappear completely.

            You will find that the signal from most small nuggets will disappear in reverse discrimination; It is when you are getting close to them that the signal in reverse discrimination from gold will be heard as a HI/LO tone, which is why you have to dig these reduced level tones; They may not always be gold but it is better to be sure than to leave a nice nugget in the ground.

            You will find that the signal from rusty tin lids and some rusty nails will disappear in rev disc but when you get close, the signal from these items will be LO/HI… You will not get a LO/HI tone from natural gold in reverse discrimination.

I decided to take the Infinium back up to the Iron mineralised hill and take some photo’s to show the sort of ground that it will operate on.

            Every piece of rock, pebble and gravel that is visible in these photo’s is iron ore; The entire hill is iron ore and I have included one shot showing a 0.15 gm piece of gold that I used as a test piece in order to give an idea of what size gold the Infinium will respond to in this mineralisation. I was able to detect this piece buried about 5cm into the gravel. With it resting on the ironstone boulder the Infinium gave a clear hi/lo tone at close to 3 inches away with the 10 x 14 inch DD, the boulder alone was giving a long quiet low tone. I am not saying that everyone with an Infinium would have been able to locate this piece of gold, but I am saying that the Infinium responded to it and that an experienced operator would have checked the signal and that there is not a vlf detector on the planet that could detect this piece of gold as a separate signal from the iron boulder 

Well there you have it, I have found my Infinium LS to be a detector that does everything that it is claimed to be able to do and it does it all extremely well.

Adrian Ross