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Impulse AQ Coil Connector False Signals


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I just posted on another thread asking why the delay range can’t be extended further. It removes capacitive problems plus a lot of fast salt noise as well as keeping in the zone for the majority of decent size gold targets. I applaud the development of he AQ’s circuitry to allow such fast delays as well as the crucially damped coils to allow this BUT at what cost. 15uS to 20uS is the Goldilocks zone for all other PI’s.......is the AQ any different? Asking because I don’t know and don’t have an AQ. Sure would Ike to try one DownUnder 👍

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12 hours ago, Joe Beechnut OBN said:

Words from Eric Foster on the subject..

Without actual in use reports on how one made with the stainless connector vs the composite one acts when dipping across the water line in salt water, we may not know how well the shield and insulator are carried through the connection with the stainless connector. The dilemma of trade offs, testing, information flow, clarity of information and interpretation of what the information really means. Frustration. I'm still leaning to paying for the expensive connector for two reasons (unless the first one isn't true):

1) The sound off from the knee to waist deep wash across the connetor shouldn't be as bad.

2) Since it is reported that they have to use the expensive connector on the Gold version, quantity pricing may help get the connector price down.

Which ever way it goes, I still anticipate having one in what ever form it is available in, when one is available.

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  • 6 months later...
On 7/8/2020 at 7:12 PM, Steve Herschbach said:

First off, I want to point out that what I am about to describe is not uncommon with high power detectors that have a coil that can be disconnected. The only way to really eliminate the problem is to hard wire the coil, which is another reason for why this option is chosen by so many manufacturers of underwater metal detectors. The White's TDI Beachhunter is a good example. The problem has its root in coil capacitance and the high voltages involved, and the difficulty of getting good shielding using a removable connector.

If the Impulse AQ is submerged halfway, so that the water level is anywhere in roughly the area indicated in the photo below, you will get continuous false signals. Just holding the unit stationary in the water at this level will cause signals as the water moves around the connection area. If you are not aware of what is happening it is every easy to mistake this for electromagnetic interference (EMI).

The problem is worst in the Tones mode, which I just happen to be using a lot. It is accentuated by a short pulse delay, high sensitivity settings, and low ATS settings. If you want to reduce the false signals, here are some solutions:

  1. Use the All Metal or Volcanic modes instead of Tones
  2. Increase the Pulse Delay to 9 or higher
  3. Reduce the Sensitivity to 4 or lower
  4. Increase the ATS to 8 or above

Or some combination of the above.

In practice this only occurs when wading, and only at a certain depth. My solution was simply to stay either deeper or shallower. This does leave a strip or area unhunted. You can either switch the settings as suggested above, or do something to change the height. Like hunt that strip with mask and snorkel, for instance. 

Anyway, hopefully this is put in the manual as it is something inherent in the operation of the detector, and can drive you nuts if you run into it and do not know what is going on. It took me several hours of detecting to put two and two together, and it was then confirmed that yes, that is the way it is.

fisher-impulse-aq-coil-connertor-false-signals.jpg

That's a great rundown and laying out of the solutions, Steve.  Mines trussed up with Flex Seal--still not quite sure if it's helping--I think so though--maybe about 30%.  Jimmy's straight cable fix seems to help too. 

cjc

IMG_3739.JPG

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On 7/9/2020 at 2:48 AM, Willy said:

Yes, you can do that to solve this problem but you then generate a sensitivity to external EMI for the whole system.

I still think of Eric's Aquastar coil with the stainless bead--shame something like that can't be incorporated here. cjc

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On 7/9/2020 at 4:16 AM, Skullgolddiver said:

I perfectly remember this thing on the Excalibur battery connector, never been a big problem with some good gel grease ...Now...Using a metallic connector installed from the source (FT plant), I think the connector electrolysis phenomenon can be on the outer part of it right ?

So I see a temporary solution : heat shrink tubing right around the end of cable and connector...

or Flex Seal--easier to remove.  I also just extend the wand to hunt that zone--like an Excal behind the arm. cjc

IMG_3739.JPG

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On 8/25/2020 at 5:54 AM, Tony said:

I just posted on another thread asking why the delay range can’t be extended further. It removes capacitive problems plus a lot of fast salt noise as well as keeping in the zone for the majority of decent size gold targets. I applaud the development of he AQ’s circuitry to allow such fast delays as well as the crucially damped coils to allow this BUT at what cost. 15uS to 20uS is the Goldilocks zone for all other PI’s.......is the AQ any different? Asking because I don’t know and don’t have an AQ. Sure would Ike to try one DownUnder 👍

The AQ limited has a 15uS setting. The 11.5 is actually 15uS. I think the reason most other PI detectors stop at 15uS is because their circuitry was unable to sample faster than that in salt or heavy mineral locations and still remain stable. That’s not to say though that the unlimited AQ won’t add slower sample rates. We shall see. 

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On 3/3/2021 at 10:00 PM, cjc said:

or Flex Seal--easier to remove.  I also just extend the wand to hunt that zone--like an Excal behind the arm. cjc

IMG_3739.JPG

I’m not so sure it’s the connector as much as the electronics in the control box aren’t shielded. My VALLON PI shields the entire circuit board and they use a 7 pin Souriau bayonet style connector. The center pin is the coil+ and all the remaining 6 pins are tied together as coil- which shields the connector. Maybe Fisher could look at that as a possible fix for the noise. I read one post who says his machine gets noisy when the water is about 6 inches down from the control box. That most likely is movement of the coil cable itself. You need to secure your cable for zero movement the best you can. Good luck everybody and spring is just around the corner here in the US !!!

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CJC, I was the person that asked Eric Foster to make the 10 inch coil for the Aquastar.  Because the big coil for the Aquastar would see too much minerals in the ocean water.  When the big coil was in ocean water 3 feet or deeper.  This would  cause the front end electronic circuits to shut down.  I hand carried the Aquastar big coil from Hawaii to Eric Foster in England.  He then tested the coil and told me that the amount of minerals in deeper ocean water would cause the Aquastar's front end electronic circuits to shut down. 

My favorite beach here has the largest shopping center which has 348 stores with in 1/2 mile, 4 or 5 TV stations with in 1 1/2 miles.  And the Honolulu main airport within 2 1/2 miles.  So needles to say there is a lot of electronic interference. I was running a bare wire from my hand grip to the bolt on the coil to help ground the Aquastar and me to earth ground when in the ocean water.  When I told Eric Foster what I was doing.  He then made me a 10 inch coil with the stainless bead.  The  stainless bead was connected the Aquastar circuit ground.

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3 hours ago, TerryinHawaii said:

CJC, I was the person that asked Eric Foster to make the 10 inch coil for the Aquastar.  Because the big coil for the Aquastar would see too much minerals in the ocean water.  When the big coil was in ocean water 3 feet or deeper.  This would  cause the front end electronic circuits to shut down.  I hand carried the Aquastar big coil from Hawaii to Eric Foster in England.  He then tested the coil and told me that the amount of minerals in deeper ocean water would cause the Aquastar's front end electronic circuits to shut down. 

My favorite beach here has the largest shopping center which has 348 stores with in 1/2 mile, 4 or 5 TV stations with in 1 1/2 miles.  And the Honolulu main airport within 2 1/2 miles.  So needles to say there is a lot of electronic interference. I was running a bare wire from my hand grip to the bolt on the coil to help ground the Aquastar and me to earth ground when in the ocean water.  When I told Eric Foster what I was doing.  He then made me a 10 inch coil with the stainless bead.  The  stainless bead was connected the Aquastar circuit ground.

Certainly unique to the Aquastar.  I had one for a while found it a bit heavy and one risked the board to make adjustments on the beach.   You should PM Alexandre he's interested in how this ground worked.  cjc

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