VLF Detectors - all makes

In the market for a VLF Detector  to add to my detecting kit , a GPX5000 & Xterra 70.The frustration i find in trying to decide in which one to buy ,is that they all have such wide ranges of output in KHZ !! The Eureka 3 freq up to 60 khz , the Fisher Gold Bug 2 the same and up to 71 khz ,etc,etc .I know VLF'S can be difficult to use ,but they definetly have a place in detecting .A while back i had the 5000 out ,trying a new spot that looked promising and after a couple hrs of no luck ,was putting it back in the car ,when i decided to dig out the Xterra 70 and give it a go,( it was in the back of my mind the post & articles i've read on the VLF  versus  Pulse ) well after about half a hour over the same area  i'd gone over with the 5000 inadvanced settings ,as the ground was very low in minerilization ,i got about half a dozen signals ,NOT dig me signals by any stretch of the imagination ,but soft bround ground noise ,with both ways of the swing !! Using i might add a 18.75 KHZ small coil . So this time i decided to bucket the targets ,the target signals quite often dissapearing once dug out ,took home and panned off ,and BINGO some colours in the dish !!    Ofcourse once the excitement wore of a bit ,the realization hit me ,that this has happened before ,and looking back in hindsight    how much gold have i walked over  ??    So really my QUESTION IS  ,really probably directed to all the various detector manufactures's ,why can't we have a detector that say you can adjust between 3 KHZ and 71 KHZ and between ,having 68 variable adjustments   ??  The reason being i feel you could adjust it to the closest output to suit the ground minerilization ,without having to sacrifice depth without  using stabilizer etc , and also the fact that we all know that ground minerilization can be so variable !! I'm certainly no tech head ,and don't professs to any answers or solutions ,but does anyone else feel this way ??  Interested in your opinions .   

Good Idea Hugh,but not with the current type of technology in use today.Variable KHz or pulse rate isn't the main issue here,but how does one go about in making a coil winding to suit all the variable changes of output frequency to optimum operation? The sensitivity of the Eureka Gold at 60 KHz is no where near the sensitivity of the gold bug 2,neither will it pick up tiny gold at the same depth as the GB2,for its coil winding ain't wound to suit more a particular frequency(eg 60KHz) than the other two.More like a coil winding wound for average all round use,but optimum to none. Even if detector manufacturer's could do as you've asked of them,would it be in their interest to do so by having one detector,one coil that suffices for all your detecting needs? I don't think so.Why the thought of it alone,would be regarded as a blatant attempt towards sabotaging their current,long term,in line,drip feed system.    

    Cheers Kon. 

.....but how does one go about in making a coil winding to suit all the variable changes of output frequency to optimum operation?

Minelab have done it,  simultaneously txing from 1.5khz to 100khz on their flagship coin/relic detectors...if you believe it that is.   
Whites on their v3i model like the one im using tx simultaneously on...22.5-7.5-2.5khz. So the question is...which of the three freq on the v3i..or Eureka gold, is better tuned for the coil they come with.?? For that matter, the same could be asked as to which coil is better suited to a detector that claims the use of 28 freq or 17 freq continuously.???? 
If the BBS/FBS detectors actually tx off the claimed amount of freq, they'd be king at finding small gold and chains ect......but their not.

Example...claimed 1.5-100khz.....it would out perform the GB2 at 71khz....not the case  is it.? 

The small amount of extra/less winding from the lowest to the highest is only very small.
It go's deeper when you look into how the FBS/BBS detectors actually work, compared to the Whites models that tx off three freq compared to how the Minelab ones work.
The Eureka only txs of one freq at a time, as doe's the x-terra/s.

The x-terra's coils are chipped to control the tx freq, so each coil is trimmed to the freq meaning its a far better antenna for the given freq. That chip could have been put in the control box (just like the Eureka ) and made to work with multiple coils at the freq you select. Thus making it far more user friendly and versatile...again, like the Eureka just a digitally controlled model.
The 18.75 khz coil of the x-terra, may work if the plugs are the same on the Eureka's freq of 20khz. ??? The windings would be very close.??

Hi Hugh
You said you got a signal then it disappeared, so you put the dirt in a bucket to pan, the colours you got when you panned? are they large enough to give a signal when rubbed on the coil?? from your description IMHO it sounds like you are possibly picking up a concentration of mineralisation & not a single target, I would be happy to be wrong.

I have tested a mates E 70 and it performed poorly in comparison to my Gold Bug Pro.

Thank you gentleman for your replys,very much appreceated .All of the opinions make sense , espically " how does one make a coil to suit variable changes of output frequency to optimium operation " it still puzzles me slightly that none of the various detector makers thou haven't come up with this idea  ,keeping us on a " drip feed system  " from a marketing / selling  point of view ,is something that i hadn't thought of either ! Glad to ,to read the comment about the top of the line coin /relic detector  1.5 khz -100 khz ability ??!! That did always puzzle me ,probably more for the fact ,if it did have such capabilitys ,why weren't more people raving about it ??  Out of the half dozen signals that i bucketed ,most dissapeared when passing by hand in front of the coil , errr no    unfortunately i didn't dribble /push them over the coil , and YES i diffently agree with you rc62burke ,there pockets of mineralisation ,i also    bucketed all of the 6 target scrapings into one bucket ,so don't really have any idea of which few colours i did get came from which hole ??   going to take a collection of containers out with me again when i go back out there again ,so i can log them  !! And yes i can beleive that the E70 would perform badly against the GB2 .What i'm trying to do basically is ,useing a electronic form of " LOAMING " the lazy mans way ,this particular area i'm searching in ,old gold bearing area ,till 1935 anyway produced rich veins / shoots of very fine / flour  gold hosted in sandstone .Did think about building rock crusher and going thru taking samples etc,etc . The terrain doesn't help much either ,slatey steep hilly country with sharp gullys,spinefex and scrub .Can't even get my quad bike in most places ,the ol timers obviously used packhorses to get  their ore out .    Gaw'd just realized that i'm starting to whinge !! even with all the mod cons & technollogy ,i have at hand      No definetly have the highest respect  for the ol timers  .   Thanks again ,every one .

kon61 wrote: The sensitivity of the Eureka Gold at 60 KHz is no where near the sensitivity of the gold bug 2,neither will it pick up tiny gold at the same depth as the GB2,for its coil winding ain't wound to suit more a particular frequency(eg 60KHz) than the other two.

    Cheers Kon. 

Kon, I used to have an XT18000 and have used a mates Eureka Gold. Very similar except the Eureka iron reject is miles better, and runs a little smoother in hot ground. I totally agree with your comment but it is only true IN AIR, or very mild ground. Take a GB2 to any hot ground and it's useless. You end up dropping the sensitivity right down to make it bearable and then that extra sensitivity goes out the window. Most of the videos on youtube are from guys using it in the US, and I think that sucks people in and when they try one on the red dirt here they get a nice surprise. As to the Eureka the new 6" goldseeker coil works very nicely in 60 khz (wishing I didn't get rid of my 18000 now) and is far smoother than the bug2 in the mineraisation. Best thing about the Eureka (and 18000) is you can strap on the 11" dd round and 20kHz and get much better depth compared to the gold bugs and goldmasters.
The GB2 would be awesome if you could flick between 71 and 19kHz, and if it had some DD coils available.

Yes I can understand what your saying there NuggInOne,at one stage,I owned both the 17 and 18000.Not exactly true there,for my tests were on virgin shallow buried untouched nuggets below the 0.4gm mark in reasonably hot ground.The new Eureka gold might operate a little quieter/smoother than the XT 18000 or the GB2 over hot ground where the GB2 would scream and yell,but have you seen what happens when you boot scrape the signal surface and switch the GB2 into discriminate mode,you'll find what's left is a loud clear positive ping,ping signal on the gold at full depth of target.Running smooth and quiet with good discriminating capabilities,don't necessarily mean your achieving greater depths on the tinier stuff than the higher frequency unit.A clear cut example of this is on all the GPX Series detectors where they'v managed to get them running smooth and quiet by cancelling most ground noise out on mono coils,but at the cost of both sensitivity and depth.Like yourself air tests mean little to me,when I'v seen coil field strength halve on positive targets over hot ground as compared to benign or low mineralized.
As for the latest Gold Bug 19KHz,ask anyone who owns one if they can run it smoothly over hot ground with its standard 5 inch dd coil in all metal? and I bet the answer will be they can't seem to get it out of discriminate mode.  

   Cheers Kon. 

Hugh62, It is possible that the bits of gold that you panned off were just randomly in the soil that you took home & werent the actual signal that you got or thought you got. I dont know about the Xterra as I dont have one but with my Whites GMT & Gold Bug 2 there is no way you can wave a handful of dirt over the coil to see if the target is in your hand as the detectors will pick up the salts in your hand & give a signal any way, target in hand or not.
NuggInOne, The Gold Bug 2 runs at the one frequency of 71 khz & doesnt have a 19 khz option.

JW

Thanks for your interest in my post . Firstly the signals that i dug were a soft broad ground noise ,typical heavy minerilised soil noise ,BUT with both ways of the swing of the detector ,AND at different angles ,DEFINETLY  not dig me signals ! In the past ,i've generally ignored these type of signals ,puting it down to just ground noise / heavy minerilisation etc .Unfortunately as i wrote earlier ,i didn't seperate my target's ,putting them all into one bucket ,so no idea really where the few bits of colour came from   There is a update on this ,i did go back out and went over the ground again ,a 100m by 100m sq area approx,with both the 5000 and xterra 70,and tryed every different setting possible with both detectors ,but nothing     And yes i agree that waving your hand in front of the coil will give off a signal ,i found this espically when i first started useing the detector years ago ,before i cottoned on to what the problem was , ( even waving a stick in front of the thing was giving of a soft signal response !! ) but i learnt that quite often just by laying the detector on the ground ,will upset it's ground balance or noise cancel  !!  now aday's i can pick up straight away  if the detectors a little UNHAPPY     And a quick auto ground balance , ( off the target area of course ) OR even  sometimes a quick auto noise cancel will quickly make it happy again , and remove's this problem .     Re reading Nugginone's comment was IF YOU COULD FLICK  between 71 & 19 khz ,and yes i agree with him it would be great . Congratulation's to also on your finds and pics ,i was just reading ,struth thou i nearly froze just looking at those pictures ,the cold and wet condtions    Lovely 32 deg here today up at sunny  Mt Isa ,nth west QLD .