Author: BT
It’s no secret that the Whites MXT has been around for a few years now but in that time it has been a bit of a sleeper in Australia. In the United States however it has gained a pretty good reputation as a gold getting VLF (Very Low Frequency) detector.
Recently I had the opportunity to discover first hand if it could live up to its reputation in our gold hunting environments.
Much of the MXT prospecting mode is based upon the highly successful Whites GMT platform with the use of Fast Auto Track and the legendary V-Sat control. This control does an excellent job at smoothing out threshold fluctuations caused by rapidly changing ground conditions in highly variable ground types.
Hook this up with dedicated Coin and Relic modes and a Salt switch and you have a highly versatile machine capable of covering almost any type of gold, coin or relic hunting scenario.
There were a number of coils available for this machine but for my first outing I chose the 5.3 inch Eclipse concentric. This coil is actually touted as a coin hunting coil by Whites but after some initial testing and witnessing its amazing sensitivity on small gold and specimens, I reckoned it would be a winner in some of my old hard-hit areas.
First stop was an area in the middle of Maryborough, Victoria, near some old surface workings. Because of the V-Sat control I was able to run the gain, or sensitivity, very high. The V-Sat controls how fast the threshold recovers from fluctuations caused by the ground changing from positive to negative or vice versa balance. To put it simply it greatly reduces noisy operation in bad ground. This control is exclusive to Whites machines and has never been copied to date. With the careful selection of the right V-Sat level you can obtain a much higher gain or sensitivity setting than would otherwise be useable without it. In other words when you have to drop the sensitivity on another machine to a level where you lose a large amount of depth and sensitivity due to too much ground noise, on a Whites machine that incorporates V-Sat you can retain much of the operational power by simply upping the V-Sat level.
“The Pilot seat of the MXT with all the info you need”
The V-Sat range is 1 to 7 then it shifts to ‘Hyper Sat’. Hyper Sat is for use in extremely bad ground and will flatten out threshold fluctuations dramatically but still give you a crisp discernible target response.
So here I was running 10 on the gain and 7 on the V-Sat. The ground noises were almost non-existent, the threshold was as smooth as silk and within 5 minutes I had my first MXT piece of gold. How big? Don’t laugh but it was a whopping 1/15th of a gram! But I was wrapped because it was a nice buzzy little signal that popped in from an inch or so deep.
Very close by was an old detector hole that had quite possibly yielded a much bigger chunk of the good stuff. I had gone over this bit of dug ground with my other detector on numerous occasions and to say I was surprised when I ran the MXT over it and got two distinct signals would be an understatement. I remember looking down at the ground and thinking “no way, there can’t be any more signals here”.
At this point I was really expecting them to be ground noise from some strange hot rock, as there were a few in the area, but from two inches down the first one was out, 0.75 grams of gold in quartz, with the next being a sunbaker that had half a gram of spongy gold attached.
Being able to smoothly run a high gain setting, retaining good sensitivity and virtually eliminating ground noise fluctuations were definitely the keys to finding these two pieces.
The MXT and its full range of accessory coils and headphones
The following week saw me at an old reef area Id also hit pretty hard in the past. First off I ran the standard 9.5 inch concentric coil just to see how it fared on gold.
It too ran nice and stable although the donut design which is becoming so popular with coil manufacturers these days, I found to be a pain in the proverbial when swung around this rocky environment. It was forever getting caught up with rocks and sticks and brought my swings to an abrupt halt when it did. Before changing it over I did snag a small specie with 0.2 grams inside. The verdict: an excellent coil on coins and relics but a bit clumsy for prospecting.
Changing back to the 5.3 saw me a happy camper once again and very soon picking up another small specimen of gold in quartz. I half expected this piece, which was lying right on the surface, to produce a mineral sound but it stayed rock solid in response after a couple of passes with the coil. After a quick crack with the geo pick I was rewarded with another small bit of about 0.3 grams.
The magic little 5.3 Eclipse coil and four specimens containing fine gold
Often with the MXT, when you pass over a small bit of rusted iron or steel in Tracking, you will notice the response diminishes or changes quite markedly after just two or three sweeps of the coil. Gold will stay rock solid 99% of the time. Minerals in a rock will do the same and change after three or four sweeps but gold in the rock will stay solid. Be careful though because the MXT has a very aggressive and highly effective tracking system. A few sweeps would be the maximum due to this fact. Repeated passes of the coil over a target in tracking mode are a definite no-no. The MXT also needs to “see” the ground and should never be air tested in Track. Hold a target in the air with tracking on and you will see a marked reduction and/or alteration in signal strength as it tracks into the target.
My next target was a very faint signal I almost missed. When I dug it out from about two inches down I was initially disappointed to see what appeared to be a bit of rusted iron. I say disappointed because the MXT prospecting mode has the best iron ID system I have seen or used on any VLF machine to date.
Ok, so there I was with this supposed bit of rusty iron but it read 15 on the VDI display and registered only a 10% probability of being iron. What’s more the audio grunt never so much as whimpered. I quickly broke it into several pieces to reveal the culprit. It was actually a piece of iron oxide full of fine gold – a very tricky piece indeed that could quite easily fool anyone just giving it a once over with the naked eye.
Anyway, I ended up getting another six more small bits of gold here for just over a gram and another small specie of gold in pyrites. Not a fortune in anyone’s books but for such a hard hit place I was suitably impressed.
Next up I wanted to see how the 10 x 6 DD Eclipse coil handled the really bad ground so I went to a spot where the gully had been gutted out  leaving heaps of really reactive hot and cold rocks (rising or dropping threshold sounds when passed over) as well as red clays and other typically noisy minerals.
How did it go? Occasionally there was a false call but compared to other manufacturer’s machines it was chalk and cheese and a place you could happily work in. Honestly, many other VLF’s would have struggled to run a sensitivity setting higher than just 50%. The MXT was doing it effectively at around 80%.
Right on top of a small gravelly rock pile I got a solid signal that read 10% on the Probability meter. After picking it up I was greeted with 0.7 grams of gold in ironstone. This is a hard machine to fool. Last up was one of my favourite places, Crystal Hills.
I had really punished this spot with my previous machine, so much so that I reckon the wildlife in the area, trees included, breathed a sigh of relief when I finished up there a number of months back.
Due to the MXT fantastic discrimination in Prospecting mode I reckoned the best area to try was going to be amongst the rubbish and the particular spot I chose was full of it. Again I reverted to the 5.3 Eclipse and chose the Plus range of the gain to see how sensitive it really was running flat out.

I must have passed the coil over a dozen Iron or bad targets when one finally sung out nice and clear with a low Iron Probability of 10%.
It was a bit of quartz and it screamed.

One smack of the hammer and there was 1.5 grams of sparkly gold and some pyrites twinkling back at me. To say the MXT in Prospecting mode impressed me is an understatement. Tracking is blisteringly fast with any glitch quickly eliminated with just a couple of coil pumps.
The V-Sat control takes it to another level altogether making it absolutely unique amongst VLF gold detectors. The worst the ground gets, the more this feature becomes appreciated. And the Iron ID system is top notch providing the operator with an impressive array of options for identifying targets amongst junk via an easy-to read LCD display.
In my opinion: it’s one of the best and most controllable VLF gold detectors.