My air tests, ATX vs SDC vs 705

This morning I woke up and the rain was pouring down. I thought great. I don't have to go anywhere and I should be able to dodge the work. It wasn't that easy. Mrs M had a contingency plan in the way of job list "B". It was all those inside jobs that I've shoved in the not enough time basket, hang the new towel rail, put in the dunny roll holder, put up a couple of hangers in the wardrobe and the list goes on. Some times you have draw a line in the sand. I said "No it's Sunday and I have a day off". She said "What are you going to do?".

I decided to do some air tests on the detectors. I've never tried it and there were some things I really needed to know. I grabbed an old strip of gyprock and marked it out from the end 800mm down to zero at the coil. Zero was about mid sheet so the detector sat on the sheet on top of a 1200 high wooden crate with the coil and 800mm of gyprock hanging over the side away from any nails. I couldn't find anywhere dry without being on concrete and under an iron roof but that's the way it had to be.

I started with the ATX. It came with the standard 12x8" DD, an 8" round mono and the big heavy 20x12" mono. I nearly always use the DD because I like the way it performs. I like the light weight of the little mono but for some reason I never feel confident using it and the 20" is just too heavy to use for more than an hour at a time. I wanted to see how they performed against each other. Then I wanted to see how much I lost reducing the sensitivity, discrimination and tracking. Finally I wanted some idea how it performed against the SDC and just for the hell of it I lined up the Xterra 705 as well.

My targets were varied. I had an aluminium can and ringpull that I had to empty to get started. I had a range of gold nuggets, I chose 35g, a 2g and a 0.07g. Then I got a few different coins, a scrap of zinc plated steel, a steel screw and a heavy chunk of rusty steel about 1.5kg. When I found the nuggets I found Mrs M's wedding ring as well. She had taken it off because it was upsetting her sorting the targets from the dirt.

The results were amazing and awfully misleading. Firstly my accuracy was poor due to having to compete with the heavy rain on the iron roof but it didn't need to be all that accurate to show me what I needed to know. I didn't go for maximum detection on a weak target. I moved each target closer until I had a good clear signal. Something I would definately stop for in the bush.

The first was the ATX with the 20" mono. The aluminium can was no surprise at 700mm. The thing that blew me away was the lousy signal from the gold. The 35g nugget didn't give me a clear 3 LED signal until it reached 220mm from the coil. I originally found it with the DD coil 400mm down in Mertondale's nasty red dirt and I measured the depth. The gold ring came in at the same depth and the 2g nugget was only half that.

Dropping a few LED lights on the sensitivity didn't affect the depth too badly but the discrimination settings made a big difference. I'll be avoiding using discrimination whenever possible. The biggest surprise was the loss of detection on the gold when I did a really good ground balance on a steel nut. If ground balancing over a hot rock has the same result I'll be walking over most gold nuggets without detecting them at all.

The ATX with the DD lost about 100mm on the drink can but lost very little anywhere else. Considering the extra weight in the big mono it doesn't seem to be worth the effort. The little mono lost another 100mm on the can and was just a little weaker all round but it still gave satisfactory results considering its convenience in tight places and its light weight. The 0.07g nugget had to be almost rubbed on each coil to detect it clearly.

The SDC was a bit more difficult to get a accurate reading on because it continued to chatter throughout the entire experience. I guess it was the chill in the air However the readings came in very close to the ATX with the 8" mono on all targets. I found that it lost very little in the detection depth between the highest setting of 5 and the highlighted 2. The salt setting 3 gave a similar reading to 5 on the regular scale.

The Xterra 705 gave an amazing performance and very clear signals. Apart from losing a lot of depth on the aluminium can it pretty much matched the ATX on all other targets and exceeded the depth of the SDC on everything except the drink can. It sat there quietly most of the time although for some reason it lost the plot on occasion and wouldn't quieten down until I reduced the sensitivity. I'm yet to work out why it has a coin and treasure setting and then I gold setting. The difference in detection depth seemed very little but the coin setting gave the operator a lot more feedback.

For me these tests showed me that this type of test does little to demonstrate the value of a detector in the field. From now on I'll take most of these youtube videos with a pinch of salt. Hopefully I'll get time this week to take all the detectors over to our test patch. We have 20 targets of varying types that have been buried in the bush in Capel sand for more than a year. I'm hoping for a more accurate result.

Phil

Hey Phil,

I reckon without a quiet emi background and any salty red clay dirt or depth to balance on, I think your not getting any true performance from any of these machines...
Maybe a video of different machines/different settings and coils at the 'DWAG Muster' may be on the cards.
Out there I'm sure is some WA stoney breakaway outcrop dirt, elluvial wash scree pans and salt lake alluvial mud to compare on. That'll be a real test and make $$$ on a video for your efforts.

regards,
ND.

NuggieDreamer wrote:Hey Phil,

I reckon without a quiet emi background and any salty red clay dirt or depth to balance on, I think your not getting any true performance from any of these machines...
Maybe a video of different machines/different settings and coils at the 'DWAG Muster' may be on the cards.
Out there I'm sure is some WA stoney breakaway outcrop dirt, elluvial wash scree pans and salt lake alluvial mud to compare on. That'll be a real test and make $$$ on a video for your efforts.

regards,
ND.

ND with my record I might find it hard to show the video with the big gold nugget coming out at the end