Vallon VMH3CS Mine Detector

[kingswood]

Day 2 report Went to a spot with a lot of ?laterite mixed in with quartz (see pic).
Vallon ground balances okay, but I still get occasional rocks that give a signal. I am learning what this sounds like however and it is a vastly different signal to the screech the Vallon makes when it hits on something metal. I tried ground balancing directly over one of the bigger lumps of rock...managed to tune that rock out, but every other rock that I swung the Vallon over then went off !!! GB back to the ground and things went well. Had a great screech and dug up another tiny slither of tin from about 6 inches. The Vallon tells you fairly clearly if its metal!! Dug a piece of smashed up bullet lead which gave a loud clear signal from about 10 inches. Things are looking good....Just need to actually wave the coil over a nugget to see if it will actually find it
If any one is a geologist, I have attached a pic of the black rocks...??basalt ??laterite??

[Qiaozhi]

If any one is a geologist, I have attached a pic of the black rocks...??basalt ??laterite??

Look here -> http://www.comparerocks.com/en/diffe...rison-34-7-997

[kingswood]

Look here -> http://www.comparerocks.com/en/diffe...rison-34-7-997

Very good thanks....Probably some type of basalt.

[Ferric Toes]

Thanks Eric. The ground balancing seems very good. I will keep trying it over different areas and see how it goes. There is a big old dry lake not far from me that is quite salty (and has a lot of gold left still apparently!) so that will be a very good test area.
I did notice that the Vallon is basically always working with a silent threshold....I wonder if increasing the sensitivity increases the threshold??...Will have to try that! From what I understand, silent is not always the best for gold detecting...

Which of the two ground balance methods are you using?

Although the Vallon is silent threshold, it doesn't take much signal to start the audio. By all means try the two higher sensitivities and way out in the open country away from electrical noise, you may be able to use them. One thing about the threshold is that is doesn't drift at all so that you are losing sensitivity without knowing it. Very important for a mine detector and useful to know for other uses i.e. nugget hunting.

I used to correspond with Chris Hake of Kalgoolie who did a lot of gold hunting on the dry salt lakes. As you say, there seems to be quite a lot of gold in them. I made some rectangular coils for him that were mounted on a trolly that was easily wheeled across the lake. The detector he had then was an SD2200. Sadly Chris died a few years back.

Eric.

[Ferric Toes]

Very good thanks....Probably some type of basalt.

I would lean to it being Laterite. It looks the same as the rocks you get in the Victorian goldfields on which I have quite a number here. The rock was laid down in sedimentary conditions from the water erosion of previous rock that had a high percentage of magnetite. This mineral oxidised to maghemite which is what gives the troublesome signal on a metal detector. Gold nuggets associated with the rock often show signs of water erosion such as rounding of the edges. Gold originates within the quartz mineral that infilled cracks and fissures within the Laterite.

Gold in Western Australia has more silver alloyed with it than gold from Victoria, hence a slightly brassy appearance. That means that it is less conductive and you need a bigger nugget for the same signal than for Victorian gold. It sounds counter intuitive but it is a fact. Same for gold rings. 18ct or 9ct rings are less detectable than 22ct rings of equal size and thickness.

Eric.

[kingswood]

Which of the two ground balance methods are you using?

Although the Vallon is silent threshold, it doesn't take much signal to start the audio. By all means try the two higher sensitivities and way out in the open country away from electrical noise, you may be able to use them. One thing about the threshold is that is doesn't drift at all so that you are losing sensitivity without knowing it. Very important for a mine detector and useful to know for other uses i.e. nugget hunting.Eric.

Thanks Eric. I have tried both the auto and the manual (fine) GB using the up/down method in the Vallon manual. I think its a case of "practice makes perfect" (if there is such a thing!).
I did increase the sensitivity to 13 and this was okay. It didnt actually change the threshold though. I agree that not much signal is needed to get an audio response. It picks up very tiny thin pieces of tin and lead very well even when in an area with lots of hot rocks!! I have noticed that it gives a signal to the odd rock, but those signals are vastly different to the loud clear screech it gives when it actually hits a target. I think more playing will help my ears adjust. Overall, I think the Vallon has a lot of potential.
Thanks for the comment about the rock too. Yes, it could be laterite. There are some here that are twice the size of a house brick and shiny black in colour....Easy to identify them as the signal and kick them away as they are making a short, almost humming noise, rather than a loud strong screech. Its a bit hard to describe...its like a flat tone rather than a loud clear tone.
I did walk along the lower aspect of a hill that was basically these rocks with very little ground to be seen. The Vallon worked with less noise if I kept it 2 inches above the rocks rather than an inch. I found the tin piece there so it seems the Vallon is still able to get some decent penetration. I tried slower sweeps and I think this gave less noise than slightly faster ones (would that be normal??)
Total detection time is 4 hours, so after 400 hours I may understand the Vallon a bit more

[KingJL]

• (I mistakenly posted this on the wrong Vallon VMH3CS thread... it was meant for this thread!!!)
  
  Received my Vallon VMH3CS today. Unit is in exceptional shape... minimal Afgan dust. Date code is 7/2010. At $270 delivered to my door, I am well pleased.
  
  
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[Ferric Toes]

It certainly looks in good shape. Most of the display housings get a bit battered; not sure why. I have made a jig so that on the bad ones I can take a skim off the edge with a milling machine to tidy it up. It is strange that the display unit is not sealed around the edge and there are two small vent holes underneath. This results in dust getting inside and all over the small circuit board although the components are protected by a silicone rubber coating.

I see you have got one with the improved arm rest, which is a great improvement on the rabbit ear type that many have.

If ever you want to take it apart, let me know, as the right sequence is not immediately obvious.

Keep us informed as to how you get on when you power it up and do some tests.

Eric.

[Ferric Toes]

To bring it up like almost new, use ArmorAll trim and plastic restorer available in car accessory shops. It shines up the coil nicely as well, even on the underside. I put it on with an old toothbrush that gets the dust out of the lettering and scratches too. The fibreglass shafts polish up nicely too as do the threads in shaft couplers and the knurled adjusters.

Eric.

[KingJL]

If ever you want to take it apart, let me know, as the right sequence is not immediately obvious.

Eric,
Thank you for the offer.... and I will take you up on it. That is my next step... dissassemnly, careful inspection, and lubrication (with silicon grease) of all seals. Your insight and assistance would be greatly appreciated.

Also, I would be interested in finding a source for an unserviceable lower unit to use as basis for a probe using a coil I have wound on a 4"x 1/2" ferrite core (1800 uH).

[KingJL]

Keep us informed as to how you get on when you power it up and do some tests.

First power on and test, the unit was very "chatty" in the front yard, with many signals repeatable, indicating that something was really there. Moved to some cleaner ground, ground balanced the unit, and found the operation much quieter. Did a test using my size 11 1/2 gold band... lying flat in the same plane as the coil, detected at 15" (led signal level 3)... lying (standing) perpendicular to the plane of the coil, detected at 12"-13" (led signal level 3). The best I could ever do with my Hammerhead with a 10 1/2" 300uH double d was 10" lying flat in same plane as the coil.

[TH'r]

Hi TH'r,
Good to hear that you have acquired a VMH3CS and it is in good shape. The detection ranges indicate that all is working fine and that you should do well with it as a relic hunting detector. What instructions did you get with it? It is usually just the field card which is quite basic. In addition to the LED display and the internal piezo speaker, there is a vibration device that you can feel through the handle. This can be disabled as it is not necessary for TH work and increases current consumption. Press C and + and hold down while switching the control knob to ON (Normal). Release C and + after 1 second.

Did a piezo headphone come with it? I was out searching farmland a week ago and found that headphones were necessary as the internal speaker has limited volume. I used Gray Ghost piezo phones as low impedance phones do not work. The audio volume can be changed by setting the control switch to the speaker symbol and pressing + or - , to change the volume level. Another useful point I learned that day was that I got better results by searching in the 'mineralised' mode in that I was detecting significantly less small ferrous items; the search being for mainly for coins.

Let us know how you get on when you take it into the field.

Eric.

Hello Eric; My senior ears experienced the afore mentioned lack of volume on my first field trip. I have since installed, with Velcro, the modified & pictured small Amp, which delivers more than adequate volume. Was an after market Vivitar amp (stereo?) system with 8002B IC's. I removed the two hard wired 2" speakers, added my own from junk box, and connected a plug from E-bay. Amp. cost me $2.99 USD from a big box overstock store.

[6666]

I have ordered one to, delivery date end of this month, fingers x'ed.

[kingswood]

I have ordered one to, delivery date end of this month, fingers x'ed.

Awesome!...Another Australian

[6666]

Awesome!...Another Australian

Hi, I was going to buy one last week but they sold out, but today they relisted and ordered one.
Begged them to send a good one
I understand that the ground in WA can be very nasty like the ground here in the Victorian gold fields
or even a bit worse, so if your machine works ok in WA, then I'm hopefull it will handle it here.
Dont get out much, but found some nice small bits in NW NSW last year and was thrilled to bits,
interesting to hear that you have salt lakes containing gold.