Whites SPP Adding Conductivity switch

[KarlS]

I'm not sure, but I don't think it is ground balance. More likely it is how the low and high signals are processed. You can add ten turn pot, but most likely it will be pain in the backside to adjust. What you really need is croase adjustment(existing pot) and fine adjustment. And that mean drilling extra hole in the box.
Karl

 

[old hand]

Thanks Karl I will have a play and see how I go regards john

 

[Roscoe]

G'day karl, Try running machine in normal GB position #8.5 then when you hit a target then turn Gb to #4. I did a quick test with my spp and i would not be detecting in GB# 4 all the time you are knocking out a lot of good stuff on GB#4. For instance sweep over a $2 coin in GB#8 then switch GB To #4 and see what happens? I found that the $2 coin completely disappears in air test when on GB#4. At this moment i would be running on normal GB and only switching to GB#4 to test target. I only had the machine for 1 day so i will have to test more.

John, I agree with you 100% this machine needs a Finer GB potentiometer. If you decide to fit one would you let me know how you do it.

 

[KarlS]

Thanks Roscoe, that must be mistake I made. I will run it in default mode next time. There still may be few goldies over there.
Karl

 

[Guest]

In high and backed of to GB 4 you must lift the coil a little to make trash or low conductive targets disappear' if it's a high conductive like a penny' the signal will still be there even 50mm or more above the surface.

 

[KarlS]

I think, not sure yet, that this discrimination method works much better with Mono coil then with DD. On other hand DD coil pinpoint much better and that's what makes me happy. I won't be using the SPP in the parks much, X-terra does very good job. It is just to get used to it, the controls and different settings, so when I get out to bush I know what I'm doing. I usually get only 4 to 5 hours detecting time and then I have to head home . Last two trips I spent most of time playing with settings instead detecting.
Karl

 

[old hand]

Roscoe I am going to try and do it the easy way it should work as we did it on all the early vlf detectors ,ebay item 3903581409197 I have ordered one,dick smith did sell them in the 80s but no more jay car don't have them .We will see how it goes regards john

 

[Guest]

This morning I went to test SPP with added conductivity switch for couple hours in nearby park. The area I have selected was large exercise lot covered in wood chip. I detect this lot with X-Terra regularly and I was curious if there is anything I missed with X-terra. The SPP was fited with 10x5 Commander DD coil, FM transmitter and I was using the earphones plugged to mobile phone. All settings at default, except ground balance that was set at 4. I left conductivity switch in default position also, flicking it into high and low when I hit target. As the picture shows, X-terra has cleaned place pretty well, except 5 cents coin and junk earring I did not find anything of value. Both the earring and the coin were about 4" deep and gave well defined signal when switch was in low, and weaker low (but not a grunt) signal when switch was in high conductivity setting.
All the iron junk gave high signal in low conductivity mode and no signal ( or just very short burp) when switched to high conductivity mode.
The battery in FM transmitter run flat after two hours so that was end of testing. I grabbed X-terra and on the way to my car, along the footpath I picked up $2.50.
I need to do more testing on some ground that wasn't so cleaned up like this one.
Karl

https://www.prospectingaustralia.com/forum/img/member-images/2409/1410829876_spp_junk.jpg

Hit the tot lot right under the swings. Don't be surprised if you pull out a few deep $2 and $1 coins 2 to 4" in
the soil right under the bark.

 

[Guest]

A DD coil will make a low tone on surface junk down to a certain depth when it turns into a high tone so in theory if you raise the coil over a low tone and it turns into a high tone it should be junk if it stays a low tone it should be something that would give a coin like signal but watch out for those aluminium tops'

 

[Roscoe]

Karl, I just done some in ground test with SPP, commander 8" mono coil Gain set at 1 to 2. I picked this low gain level as it gave clear signals on $1-$2 coins at 6" plus, but not to deep for general park use.

Test coins were 150mm in ground using machine speaker.

$2 coin GB8.5 low tone GB4 coin disappears
$1 coin GB8.5 low tone GB4 coin all but disappears if swept slow, fast sweep gone.
50c coin GB8.5 no signal GB7 or 9 low tone GB4 high tone
20c coin GB8.5 high tone GB11 low tone
5-10 cents high tone could not shift them
I tested a Iron nail GB8.5 low tone Gb4 high tone. Will have to test more Iron targets?

So for chasing $2 & $1 coins in parks i will set my gain low at 1-2, GB8-9, find a low tone target that's sharp and turn GB down to 4 if target disappears then there is a fair chance it might be a $2 or $1 coin.

John, I tried that number in ebay and nothing came up?

 

[KarlS]

Thanks Roscoe for info. I hope I can do about one and half hours testing tomorrow morning. Have to bring few coins with me, just in case there is not any in the ground. I have cleaned up surrounding parks with X-terra pretty good. I won't be using SPP in grassed areas of the parks, I just don't like to dig deep holes in grass .
What value of ten turn pot are you guys after, I'm retired electronics technician I may be able to find it for you.
Karl

 

[old hand]

OK Roscoe hope this works my computer skills are not to good

wedid use some thing simular to this on the old vlf det regards john

 

[KarlS]

Thanks Roscoe for info. I hope I can do about one and half hours testing tomorrow morning. Have to bring few coins with me, just in case there is not any in the ground. I have cleaned up surrounding parks with X-terra pretty good. I won't be using SPP in grassed areas of the parks, I just don't like to dig deep holes in grass .
What value of ten turn pot are you guys after, I'm retired electronics technician I may be able to find it for you.
Karl

 

[Roscoe]

Thanks John, I see what you mean now thanks. Do you just remove the original knob and just fit that one into place? This would be handy for prospecting for sure.

Karl, In a few weeks or so i might pick your brain on that conductivity switch mod mate, if that's ok?

 

[KarlS]

No worries, it's really easy if you can find someone to crimp wires into plug.
Karl

 

[old hand]

Roscoe if you have a look at item 3903581409197 its a old whites gold master on USA ebay this is exactly what we did us easy to fit but I cannot find that type ,So I will try and mod the one in the picture to fit regards john

 

[Guest]

Nice work Karl! being able to reverse it is a huge deal... Warranty wise..

Love the way you think, if a feature doesn't exist DIY...

 

[KarlS]

I went this morning for about an hour for another test with SPP. After trying different settings suggested I come to conclusion that although it works, it takes too much time to muck with ground and gain setting for not so accurate discrimination.
So I set SPP to default settings and increased gain to about three quarter full and flick conductivity switch to high. Then I dug on all low sounds. In hunted out Tod lot I got two 2 dollars coins, 20 cents and even 5 cents coin. Plus hand full of junk. But coin to junk recovery ratio was not that bad. I think I will use this setting form parks around here. I think it should detect silver as well.
$2 were 4 and 6 inches deep and gave very localized growling sound. The 20c gave much mellower sound and 5c low tone
Karl

 

[Roscoe]

That's interesting karl. Do you think your conductivity switch is working? 5c 10c 20c are all high tones (low cond.) on my spp, so if your switch was set to high conductivity (low tones) then you shouldn't have got any signals from 5c 10c 20c coins. Maybe the DD coil is confusing the high and low discrimination?

I agree Karl if chasing modern coins then use your x-terra. But if looking to clean out an area or chase deep old coins then the SPP would be the one.

 

[KarlS]

The switch is definitely working. I was wondering too as what's going on . Tested again - it is simple. With gain set high, the switch in high conductivity mode the nickel coins will be still detected but only at about half a depth they would be detected if the switch was in low conductivity position. The vice versa apply to goldies. So setting the switch in one position doesn't completely eliminate signals from the metal that is in opposite range of conductivity, but it greatly attenuate those signals.
Well, all what I have to do to now is to come up with setting that will find nice nugget every ten steps.
Karl