FAQs

By Jack Lange

Most questions about detectors have been answered in the Web site and printed articles such as “Which detector for you” and the various detector test comparisons, and will not be responded to again here. However some common queries may be directly answered here. Likewise, questions regarding coils are answered in the article, “Confusion over Coils”, but some basic queries may be answered here also.

DETECTORS

How deep will they go? The best of modern prospecting detectors can detect pea size nuggets at up to 34cms, coin size nuggets at up to 45cms. Matchbox sized nuggets at up to 80cm.

Is it worth buying the top of the range GP 3000 detector? That depends on your finances and how much time you will spend detecting. Certainly full timers and very serious amateurs will get their investment more than paid for by buying the best.

Is the GP 3000 much better than the GP Extreme? The GP 3000 is not a radically different detector to the GP Extreme. It is basically the same but has improved software which can give a quieter and more stable operation in some conditions. Reports are coming in from experienced operators that they get a little extra depth, especially in highly mineralized soils.

How good is the SD2200 series?  Very good when you compare it with all detectors on the market, but they don’t ground balance as well as the GP series and are not quite as sensitive, and they don’t have as many bells as whistles and their discriminator is not as sensitive.    

Can you use the SD series or the GP series on the beaches and parks? Yes you can although they are far from being ideal. As their discriminators only work on iron near the surface, you have to be prepared to dig a lot of junk.  Also, you really need a detector which will not respond to junk iron and other unwanted metals such as aluminum at all. Imagine if in every square foot of soil there were 5 nails and only 1 coin. Well you wouldn’t want to get a signal on the iron at all.

Is Auto ground balance a big plus?  Yes, because you can cover the ground quicker and iron out mineralization noises more easily, and it’s more hassle free detecting.

Do detectors need servicing?  No. There is no maintenance programme for detectors. Detectors should only be sent back to Minelab if repair is needed. If they are working properly, leave them alone.  However checks should be made on the condition of headphones, power cables, because that’s where 90% of problems develop. Batteries need checking when over 3 years old as well. 

Can SD or GP detectors be used in the rain? Not really, they don’t like moisture and even if you cover the control box with a plastic bag, atmospheric humidity may make them play up. They often won’t work properly in thunderstorms either-they get background clatter.

What about using coin-treasure hunting detectors on a goldfield?

They can’t cope with the mineralized soils of the goldfields and are poor performers to varying degrees.

Why does my GP detector threshold occasionally make erratic noises? Thunderstorms play havoc with detectors, sometimes they may still be a long way away and your detector will sense them before you do. Hot windy days may produce static electricity and make the detector “chatter” for a few minutes. Wait and it will go away.

Other problems may be earphone or power lead cables that are starting to break up through constant flexing. To test, wriggle the power cable next to the control box and the headphones at either end of the cable, and if this creates, noise, or silence, repair or change it.    

COILS

Which is better, a Double D coil or a mono coil?  Neither is BETTER than the other, they’re for different purposes. You really need both. The DD coil copes with heavily mineralized soils dramatically better, so you can use them anywhere in Australia, but they don’t detect quite as deep as a similar shaped mono coil. For maximum depth use a Mono coil, but be aware that you can’t use when the ground gets extremely mineralized, which is not that rare. Also the SD and GP series won’t discriminate with mono coils.

Why different sized coils? Big coils are best for big nuggets but are poor on tiny ones. Little coils are best for tiny nuggets but lack depth on big nuggets.

Why Eliptical shaped coils? Advantages are: longer length for their weight which means faster and lighter ground coverage. They are narrower for fitting in tight places, and pin point a bit better. Disadvantage is that a round coil of equal length will detect deeper.

Do Coiltek Pro series coils detect deeper? Yes, without sacrificing stability and quietness they will detect about 7 to 10%deeper than the previous DD coils. But they drain the battery 20% faster, which is not a major problem.

What about the new ‘Nugget finder” range of coils?  Being of fiberglass construction they are more expensive but are very quite in operation. They offer unbeatable depth for their size. All reports so far have been positive.   

BATTERIES

Do 7.3 volt battery systems have any advantage over the standard 6 volt batteries? 

Yes and no. Minelab say that the GP’s are regulated internally to reduce current to 6 volts anyway. So there’s no point in increasing voltage with a GP detector. If you use the SD series with the standard 6 volt battery, you might begin the day with 6.7 volts and if the battery is older, the detector may drop off in performance by the end of the day. With a constant 7.3 volts, you will have optimum power all day long, so it’s a very safe set up. But if you use a healthy standard and change it at midday, there will be little or insignificant depth advantage by changing to a 7.3 volt system.

Will a battery last all day before recharging is needed?  

A healthy battery in a Sd2000 or Sd2100 will last about 12 hours. Sd2200D about 11 hours. GP Series about 10 hours. However always top the batteries up each night after use for maximum performance.

Can I burn a battery out by overcharging? Only if you use the 240 volt chargers that are standard with all SD/GP detectors, this is especially the case with the small 4.5 A/H batteries. All other chargers including car chargers and regulated GP 240 volt chargers are regulated to trickle charge when batteries are full.

How can I charge my battery in isolated places? Most people use the charger that goes into the cigarette lighter of your vehicle. If the car battery is in good condition, it should easily charge 2 SD/GP batteries and still start the car in the morning, but you should drive the car the next day for at least 10-20 minutes to recharge the car battery. If you aren’t detecting far from camp and therefore won’t be driving the car much, you can buy a self contained 12 volt battery jumpstart system as an emergency back up. It can be recharged with a solar battery charger or petrol driven generator, and of course you can recharge your car battery the same way.

How good are the new Nickel Metal Hydride batteries? Their advantage is the weight saving as they only weigh 400 gram, which is less than a quarter of the standard lead acid batteries. They come with a 10” power cable and may be velcroed to the control box which removes the need of having a long cable going around you to a backpack. The standard 12 volt car charger works well with them.    

SIGNAL ENHANCERS

Do I need them? Probably. SD’s or GP’s don’t have a volume control, so it is hard, and sometimes next to impossible to hear the deepest signals, especially with small headphones. An enhancer is really only an external volume control to help you hear the faint signals, especially on windy days.

Headphones- My large black headphones make my head too hot.  Lightweight under chin Lanier stethoscope style fit into your ear and are cool and comfortable although their speakers are weaker and you need a signal enhancer with them.  However in cooler weather the large Koss headphones give superior sound and clarity and you may not need an enhancer with them if your hearing is 100%.

MAGNETS, do you need them on the goldfield?  90% of your junk will be ferrous (Iron) Even the SD2200 or GP series will not discriminate tiny boot tacks or bits of wire, and it can be a waste of time in sorting through the soil in the heap to see if it’s a small bit or iron or gold. A strong rare earth magnet will pull the iron through the soil and save you time and energy. Ordinary magnets are too weak for most jobs. Also deeper iron targets will be out of range of discriminators, so once you have dug the junk out of the hole, a quick scan with the magnet will pick up any iron. 

ACCESS TO LAND

Do I need to get permission?  State laws vary, check with your Mines or Minerals and Energy Dept. Generally, you need permission to detect in privately owned land, (in QLD in writing)  You also need consent from lease holders or Exploration License holders. (In WA, the mines Dept can overrule refusal on EPs and pastoral freehold).

Crown land where there is no national park is generally OK, state forest authorities will usually grant permission or they don’t worry about detector operators but there are exceptions.

If not sure, check first. Some goldfields have permission and access worked out for you. Some gold towns have “commons” where permission is not required.      

GPS SYSTEMS.

Do you need them? Some do some don’t. They are useful if not essential for prospecting new country because: 1. You can find the most direct route back to your car. 2. You can find the spot where you or others found gold once before. 3. You can record co-ordinates of gold spots that you find on maps and the GPS will lead you there. If you only poke around well known spots and aren’t walking too far from the car, you don’t need them.   

If you have any other questions please contact me.  Good luck out there.

Jack Lange