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HH PI vs. high power PI's like TDI or Goldscan 5c

Phlipper

New member
I have been rolling with a HH PI for wet sand and wading applications over the last couple of years. I really like them, and, as a matter of fact, have just picked up a second one for use as a back-up.

I know this question is impossible to answer conclusively because there are so many variable factors involved, but I was wondering if anyone could give me a rough idea of what the performance gain might be by going to a White's TDI or a Goldscan 5c or maybe some other high power PI over the Headhunter? I generally hunt a huge beach area with very fine sand an a large tidal range---8 foot +++, so I really need all the depth I can muster. I think my Headhunter fitted with the 11 inch coil tops out at about 14-15 inches on an average gold ring . At that depth, the signal is also quite small and easy to miss.

I am looking for real answers here, not baloney or fish stories. If I can only eek an inch or two of greater depth, my inclination is to stick with the Headhunter. If I can get substantially greater depth, I might take the plunge and go to one of the high power units. Thanks in advance for your input and experience.
 
Give me about a week or so and I'll get back you with results from my
Minelab GP3500 which I plan to hunt the beaches with.
I have used the Goldquest SS (10us) and have depth recordings from that machine as well as
the original Deepstar.
Have you actually tested a gold ring at 15". Hard to measure depending on size and shape of the ring.
Best to use a standard target such as a US nickel. The Deepstar hit a nickel at 14" to 15" so that is the benchmark for me.
I will post my results when the 3500 gets here on a US nickel.
Tony
 
http://www.youtube.com/watch?v=8Dch7XjHcSE

I ran into this video and found it very interesting. I repeated the test using the same method and found similar results---I could get a discernible signal on a US nickel at around 15 inches or so. My observations in the field have been similar, though I know how difficult it is to be certain of the depth of a field dug target.
I am no expert on these matters and am not an engineer, but my understanding of PI technology is that if I can get 15 inches on an object in an air test, that depth should be repeatable on a moderate/lowly mineralized salt-water beach.
 
Tony,
I've got the Goldscan 5c.
If you ever want to see how it compares on a trial like the last one we did with the Deepstar, let me know and I'll come and compare it.
I'm just as curious to know.

david di
 
Hello David,

Good to hear from you.....I'd be happy to do some tests when it cools off.

Maybe in a few weeks time.

Hope you are well,
Tony.
 
I have just returned from the beach with my GP3500 fitted with Commander 15"x12" Mono.

With a US nickel dropped into the bottom of a measured length of PVC tubing and the tube then buried flush with the top of the beach sand, a definite diggable signal was attained at 16"-17".
I was astounded that I would be able to break the holy 15" barrier. This is the first detector that I have owned that has achieved this including Garrett Seahunter, Goldquest SS, Minelab SD2200v2, Sovereign GT (PP mode and Amp).

Relevant settings were;
Tracking = Fixed
Coil = Mono
Soil = Normal
Boost = Deep

This was heard using a speaker/amp set up.

I am very, very impressed.
Interestingly, there was only a small increase in depth when using our Aussie $1 and $2 coins. $2 coin was 13"-14".
It was the US nickel that showed the biggest jump in depth compared to all previous machines.

Tony.
 
I currently have a TDI with standard 12' dual field coil and I used to have a HH and I can't compare them head to head, but I not sure would gain much if any with the TDI, plus the HH is way lighter. I think the TDI pinpoints better tho. There are a lots more coil options available for the TDi. If you do decide to get a TDI I would hang on to one of your HHs
 
Thanks for the replies.......
There is just no way I would go with one of those monster Minelab gold machines for beach work....especially for a gain of 1 inch !!!
Looks like I will be sticking with my Headhunter !!!
 
Okay, here are the facts;

HH PI is a low powered machine as is the Goldquest SS (both running at 10
 
''''''''''' "Plus, I can sweep big 18" coils and cover an area that the 11" coil can only dream of."
For how long???
 
With a bungy........10 hours.
 
RE: "stupid air tests"

"There is no reason an air test should be worse than an "in ground" test, except for noise. When I do tests in my garden, which is in quite a noisy location, it is very noticeable that the noise diminishes as the coil is lowered toward the ground, even from 6 inches down to 1inch height. For an air test, always have the coil horizontal. Noise signals are polarized so that a vertical coil will always pick up far more noise than a horizontal one. For a realistic air test, lay the coil on a piece of 1in thick wood, MDF, or plastic on the ground surface, then wave a target over the top of the coil. The range obtained will not be measurably different to that if the target was buried. The above is true for PI detectors, but not necessarily so for induction balance types, where the operating frequency can make a very noticeable difference."------Eric Foster


And you are way off on your HHPI depth figures. I have buried a 7gm 14kt gold band at a measured 15 inches in wet, salt sand and gotten a discernible signal. This was, admittedly, on an island with almost certainly very low levels of EMI...but that was the point.
 
So please tell me how far I am off with my HHPI depth figures on a US nickel...1"...2"...3"...4"..... ???

I'll stand by earlier statement of a US nickel at 12" to 13".....I make no reference to a gold ring depth as there are too many variables (unless we are all using the same ring).

My Goldquest SS at 10
 
This is a good read and from Eric himself.....the second last sentence suport my tests as well.

""A PI relies on a strong current pulse into the coil to obtain maximum depth. The more current into the coil the greater the potential of obtaining more depth. Next a very low noise front end of the detector is required so any return signal can be noticed. This takes a lot of engineering time and energy to maximize this feature.

So, as a general rule, high power PI's go deeper and those that have the greatest development in reducing front end noise also have a tendency to get the greatest depth.

Typical high power PI's include the ML PI series, Eric Foster's Goldscan series, and the Whites TDI. There are others, but these are the most often referenced. These detectors use heavy batteries so they can provide the greater current needed to maximize depth.

Lower powered PI's such as the Beachscan, Goldquest, Headhunter (HH), Whites dual field (DF), C Scope CS 6 and some of their other PI series, as well as other brands using typical AA batteries are usually a low power or lower powered than the above mentioned high powered PI's. Normally, these detectors have a current limiting resistor in series with the coil to limit the current, which in turn extends battery life.

Many of the low powered designs used today or even those of the past are detectors originally designed by Eric Foster. The evolution of some follow closely to Beachscan. The Headhunter is one of them that I believe was built between the Beachscan and the Goldquest. All of these are low powered PI's and most, but not all use, 8 or so AA batteries.

Now, the HH uses two 9v batteries. This is more voltage than that produced by 8 AA's but the two 9V cannot and do not produce nearly as much current into the coil as the AA battery pack and it is the current into the coil and not the voltage that is what is needed to produce the stronger pulse. The two 9v batteries was chose to provide the necessary voltage for much of the control circuitry and not to provide more coil current and do so at a lighter weight. In fact, I suspect a larger value resistor is installed in the coil circuitry to reduce the coil current than found on the Beachscan series. Also, keep in mind that is is a larger pulse current is what is needed to increase depth.

Keep in mind the Minelab PI series uses a heavy duty 6 volt battery that also uses more pulse current than other PI's that I know of even though the voltage is less than most others including the GS 5 and TDI. Also keep in mind that the ML PI also goes the deepest and does so because of both the increased current into the coil and the advanced engineering in reducing noise generated in the front end of the electronics. This advanced depth capability is also reflected in the price of the detector.

So, in a nutshell, the operating voltage by itself has little to do with just how deep a PI will go.

Now, discussing the low powered PI's such as the HH, the Beachscan, the Goldquest, and others, the low power label has little to do with the depth potential. Yes, they do not put the largest pulse into the coil, but the increased repetition rate helps in the depth potential. No, the low powered PI's won't go as deep as the high powered PI's but the depth difference isn't as great as one might think.

One other factor that applies is the fact that the technique presently used to ground balance a detector such that one can ignore or cancel the ground mineral signals is done by adding more samples taken later in time and then subtracting the later signals that have been amplified enough such that the signal from the ground in the later sample equal the main sample and the later is subtracted from the main sample. The result is the ground signal appears to go away. What also goes away is part of the signal from many targets. Thus, ground balancing detectors will not have the depth on many of the same objects as a straight PI of similar design not using or having the ground balance feature. This is why on the TDI, turning off the ground balance (GB) in areas where it can be done results in more depth on most objects. This is also why many TDI owners complain that they can see an obvious depth loss on some objects when testing with the GB on versus GB off.

I mentioned the low powered PI's do quite well against other PI's and part of the reason is the fact they do not have the ground balance system. So, they do not suffer the depth loss caused by using a GB design.

The bottom line is there are a lot of factors involved as to what affects the depth potential of a PI detector. Also keep in mind, there are anomalies not related to the detector that can influence the potential depth one might be able to detect an object. Normally, this occurs on a one time basis and is not the norm. Normal repeatable depth capability is generally much less. However, we as humans demand our bragging rights and take advantage of them. So, it is not unusual to read of abnormal depth capabilities being posted. This is far more common on some of the gold prospecting forums where one can easily picture a fisherman's ruler being used.

Now, with all the above mentioned info I will also mention that something as simple as EMI (external electrical noise) plays a large part on what one might be able to detect an object, so testing should be done often and at different locations to really get an honest evaluation. While building coils I ran into some strange things that stumped me at first and one of those things was the noise factor. I found while tweaking coils I could get depths ranging from about 11" to a maximum of 17" air test on a nickel. Now, that is a huge variation that caused me some problems because it wasn't consistent. So, coil testing became a challenge. The final result was there was very little depth difference between two similar size and shape coils once all the other factors were equal. Oh yeah, the realistic nickel depth of detection on my low powered PI's was about 11" to 12" and that was on a good day.

I hope this clears up some of the errors in thinking many people may have as well as why one can read such dramatic differences in postings about depth of detection."
 
hi,
a series of tests was carried out in Europe
with many pulsepowers, gp, tdi

Aquastar was the best on low conductors = 18K gold and white gold / palladium
a more realistic test of nikel .................

one machine is better, the Manta, PI prototype high voltage 8.8 us

:yikes: https://www.youtube.com/watch?v=f6OzVYUOdS4

http://www.mantametaldetectors.com/news/
 
Thanks Mr. Bill.........I was giving the HHPI too much credit at 10
 
LE.JAG said:
hi,
a series of tests was carried out in Europe
with many pulsepowers, gp, tdi

Aquastar was the best on low conductors = 18K gold and white gold / palladium
a more realistic test of nikel .................

one machine is better, the Manta, PI prototype high voltage 8.8 us

:yikes: https://www.youtube.com/watch?v=f6OzVYUOdS4

http://www.mantametaldetectors.com/news/

Thank you......very interesting. I shall watch !!!
 
Tony said:
So please tell me how far I am off with my HHPI depth figures on a US nickel...1"...2"...3"...4"..... ???

I'll stand by earlier statement of a US nickel at 12" to 13".....I make no reference to a gold ring depth as there are too many variables (unless we are all using the same ring).

My Goldquest SS at 10
 
Thanks Phlipper.......,I have been wrong more times than I can remember but during this time I learnt a great deal....:)

I am always happy to contribute to this forum but my aim is to never sound "big headed", etc as I am always still learning about these machines. I guess it comes to trying so many different machines and spending a great deal of time doing solid tests over and over (so as to rule out any unknown variables). I have been asked many times why I am so "particular" about detection depths. It is because when I first started detecting, there were so many claims of 18"+ on coin/ring sized targets and I could never achieve this feat....what was I doing wrong, why were my machines faulty ??? I was calling the manufacturer's and asking why their machines couldn't do this and that.........bitterly disappointed when I realised what was a realistic depth but relieved that it wasn't me or my machine.
All "AA" battery operated PI's are very close in performance (they range from about 10
 
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