Vallon VMH3CS Mine Detector

[Mdtoday]

For anyone in OZ looking for the 6 pin connector Eric was referring to in earlier posts about audio adapters (UTS6JC10E6) was quoted.
It is available from Element14

http://au.element14.com/souriau/uts6jc10e6p/plug-hiseal-size10-6way-pin/dp/1795870

Brian

[tifred]

thank you Brian

[Ferric Toes]

Yes I use the quick compensation at times too when the machine false signals for no apparent reason....
I do wonder if it does need to be ground balanced again when the sensitivity is changed....Hopefully Eric has an answer
Intuition tells me that if you make the thing more sensitive, then it would be more sensitive to ground noise also....so another GB may do the trick...

Not knowing how the ground balancing works, it is difficult to answer with any certainty. Since the detector is affected more by EM noise at higher settings, it seems logical to assume that ground noise will increase also. In an area where the ground is quiet it maybe beneficial to GB at the higher sensitivity and then switching down to default gain should maintain an improved GB.

It is reported by others, and confirmed by myself, that Australian ground in noisier in the heat of day and quieter at night when the ground cools down. After rain, the ground is also quiet. This is because the heated ironstone on the surface shifts it's time constant slightly compared to the ground that is in shadow or buried. For gravelly ground in the sun you end up with a spread of TC's which the GB cannot balance optimally. At night it all cools to about the same temperature and if it rains, even more so, and the spread of TC's is at a minimum. Hence less noise.

I have confirmed this effect in the lab by heating and cooling samples of ironstone and plotting the decay time.

Eric.

[kingswood]

Not knowing how the ground balancing works, it is difficult to answer with any certainty. Since the detector is affected more by EM noise at higher settings, it seems logical to assume that ground noise will increase also. In an area where the ground is quiet it maybe beneficial to GB at the higher sensitivity and then switching down to default gain should maintain an improved GB.

It is reported by others, and confirmed by myself, that Australian ground in noisier in the heat of day and quieter at night when the ground cools down. After rain, the ground is also quiet. This is because the heated ironstone on the surface shifts it's time constant slightly compared to the ground that is in shadow or buried. For gravelly ground in the sun you end up with a spread of TC's which the GB cannot balance optimally. At night it all cools to about the same temperature and if it rains, even more so, and the spread of TC's is at a minimum. Hence less noise.

I have confirmed this effect in the lab by heating and cooling samples of ironstone and plotting the decay time.

Eric.

Thanks Eric. I will try your idea and also will try GB again when sensitivity is increased to see if all quietens down. It does get more "chirpy" when on 13 than it does on 12...will see if another GB while on 13 stops some of this.

[Carolina]

I have noticed with my VALLON, a east to west sweep will produce a false where the return west to east is silent. Likewise a north to south and south to north is also silent. If the signal is not repeatable in west to east, I move on. Keep in mind I only hunt in salt water beach's. I have also removed sand to see if the signal becomes repeatable west to east to no avail. Another thought is in other cases, how can you be certain the chatter is ground noise, RFI or EMI? Another thought is maybe the machine is telling me I am just running it to hot for conditions? Re- ground balancing has little effect for me. Quick compensation does at times calm things down. Sweep speed also plays a role in these responses. Slow down. The above are two distinct responses. Chatter and non repeatable falses.

[Mdtoday]

I have noticed with my VALLON, a east to west sweep will produce a false where the return west to east is silent. Likewise a north to south and south to north is also silent. If the signal is not repeatable in west to east, I move on. Keep in mind I only hunt in salt water beach's. I have also removed sand to see if the signal becomes repeatable west to east to no avail. Another thought is in other cases, how can you be certain the chatter is ground noise, RFI or EMI? Another thought is maybe the machine is telling me I am just running it to hot for conditions? Re- ground balancing has little effect for me. Quick compensation does at times calm things down. Sweep speed also plays a role in these responses. Slow down. The above are two distinct responses. Chatter and non repeatable falses.

That's interesting Carolina and I agree on your points. My experience on even mild ground with different PI units the sweep speed and height being kept at a steady pace/height helps a great deal.
I generally notice interference more as short duration but higher amplitude chirp or buzz sounds. If I'm unsure, I mark the ground and move on then come back to the same point later and double check.
We have just had some rain and I was heading out to the goldfields to test my unit but work called me in...

Brian

[kingswood]

I have noticed with my VALLON, a east to west sweep will produce a false where the return west to east is silent. Likewise a north to south and south to north is also silent. If the signal is not repeatable in west to east, I move on. Keep in mind I only hunt in salt water beach's. I have also removed sand to see if the signal becomes repeatable west to east to no avail. Another thought is in other cases, how can you be certain the chatter is ground noise, RFI or EMI? Another thought is maybe the machine is telling me I am just running it to hot for conditions? Re- ground balancing has little effect for me. Quick compensation does at times calm things down. Sweep speed also plays a role in these responses. Slow down. The above are two distinct responses. Chatter and non repeatable falses.

Thanks for this. I dont think its EMI....its more like chirping on the ground, so perhaps is running to hot. Never have an issue with sensitivity at 12.
I havent really noted any west-east differences, but will take special note tomorrow
I plan on starting out with the sensitivity at 13 with a GB and see how it handles it.

[Davor]

Vallon is very sensitive to EMI. that's about the only part one may complain about. However, places this detector is mostly used are seldom infested with EMI.

[Teleno]

Vallon is very sensitive to EMI. that's about the only part one may complain about. However, places this detector is mostly used are seldom infested with EMI.

My Vallon came in today and I've just unpacked it.

I'm trying it at home keeping the coil in the air away form metals. After the start routines, the detector beeps intermittently and the first 3 - 7 LEDs can't stop dancing. Then I went out to the street (blocks of 4 story buildings on both sides) and it still does the same.

It responds to metal as expected though, but the spurious signals are continuous. Pushing "C" doesn't help. Reducing sensitivity helps only a bit.

I wonder if you guys manage to keep it quiet or I just happen to have got a defective unit.

[Carolina]

If it responds properly to it's modes of operation, vibrate,vibrate/LED, vibrate/LED/speaker, volume control, manual compensation,manual frequency search, etc. and no error sequence off LED's are present, my bet would be EMI. Have you searched or changed frequencies? I think EMI might be the lowest early morning around 4 or 5 AM. It certainly sounds like EMI to me.

[Altra]

My Vallon came in today and I've just unpacked it.

I'm trying it at home keeping the coil in the air away form metals. After the start routines, the detector beeps intermittently and the first 3 - 7 LEDs can't stop dancing. Then I went out to the street (blocks of 4 story buildings on both sides) and it still does the same.

It responds to metal as expected though, but the spurious signals are continuous. Pushing "C" doesn't help. Reducing sensitivity helps only a bit.

I wonder if you guys manage to keep it quiet or I just happen to have got a defective unit.

Go back in this thread to Erics post #722 page 29 or so. You need to adjust the frequency until you find a quiet channel. It made a big difference for me.

[kingswood]

I can now confirm that when I increased the sensitivity to 13 and did another GB, the vallon was much more stable
In fact, was able to stay on 13 for the whole 2 hours.
Dug about 2 foot down for a signal that screamed on an old pushed heap on our block!...Got quite excited!...Ended up been half a rusty can that someone has thrown down an old goanna hole
Good depth

[Mdtoday]

I can now confirm that when I increased the sensitivity to 13 and did another GB, the vallon was much more stable
In fact, was able to stay on 13 for the whole 2 hours.
Dug about 2 foot down for a signal that screamed on an old pushed heap on our block!...Got quite excited!...Ended up been half a rusty can that someone has thrown down an old goanna hole
Good depth [ATTACH]39774[/ATTACH][ATTACH]39775[/ATTACH]

Thanks Kingswood, Yep, same here, so that's a win I reckon
on the other hand Kingswood, you can't be too far away from a bit of good colour
how do you find the audio tone after a bit of use?

Brian

[Ferric Toes]

Vallon VMH3CSME

Or, Change Search Coils More Easily.

I had a blitz on a Vallon over the last couple of days and changed things around to make it a more versatile machine for hobby use. It means pretty well a complete strip down to do it but it all worked at the end of the day. The first thing was to use the 6 pin socket on the front as a coil connector instead of audio and data. I was going to change it for a Souriau but decided to stay will the MIL one as it was in good condition. Next to go was the cable in the shaft and the 6 way connectors which seen to be a Vallon special and almost impossible to replicate.

The Vallon swivel on the shaft has to be cut off and a simple adapter piece made to join the bottom end of a Whites shaft to it. The Vallon stock coil is modifiable to take a cable out of the top and adapters made so that the Whites swivel end can be used.

The coil cable ends up going through the black tube into the electronics box, but the same black tube now takes the audio to the 3.5mm jack on the rear support just below the battery cap. Much more convenient. There is enough room to get a 1/4in jack socket, but I decided that to test the concept a 3.5mm one would do. Finding a place for the step down transformer and filter for the audio was a bit of a challenge as there is little room in the main box. That is where it ended up though, potted into the dessicant tablet, after it had been emptied.

Eric.

[Carolina]

I like it !!! Also the model # !!!