KarlS
Karl
John, is it a ten turn potentiometer or vernier dial that attaches on existing pots shaft?
Karl
Karl
DD coils and the SPP
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Karl its a vernier that attaches to the pot shaft its ten turn .
this is the type we used in the 1980 s but I cannot find one of them so , its worth a try nothing to loose regards john 
Ronnie and Oldhand, Just so i know that we are on the same page here about the hiccup sound. When do you hear this sound? Is it only when you are ground balancing the detector or is it whilst you are swinging the detector? or both? or something different?
Its when you are swinging the detector, today with a dd on I got it do the same thing but I had to move GB 1 to 2 marks back towards the off position, in other word it was out of GB. Last weekend I was on one spot of ground and the threshold stayed beautiful and stable just like the detector was sitting on the ground turned on, another spot with the GB set as near as I could get the hiccup ever so often brake my consecration and having to come back and go over the spot again is a pain . I'm thinking on some hot ground the GB is that fine it is hard to get it perfect regards john
Well i am glad i asked, I have not experienced that before. When you re-ground balanced at the spot you got the Hiccup, did the detector re-balance ok? 1- 2 notches out that's a huge ground balance shift, wow? I have not experienced the hiccup whilst swinging the detector. I think your hiccup is different to my hiccup.
The Hiccup i refer to is when i ground balance and find the balance point the detector makes a hiccup sound when lowering and raising the coil. I have not found this to bad, just as long as a constant coil height is kept. My coil is always touching the ground so it doesn't bother me to much unless i have to break contact momentarily with the ground. I also found if i apply to much gain this hiccup was the detector letting me know to reduce gain.
I always check my ground balance every few yards when detecting, i got into the habit of this as some of the areas i detect the ground varies significantly. I suppose i will have to experience this myself when in the gold fields.
The Hiccup i refer to is when i ground balance and find the balance point the detector makes a hiccup sound when lowering and raising the coil. I have not found this to bad, just as long as a constant coil height is kept. My coil is always touching the ground so it doesn't bother me to much unless i have to break contact momentarily with the ground. I also found if i apply to much gain this hiccup was the detector letting me know to reduce gain.
I always check my ground balance every few yards when detecting, i got into the habit of this as some of the areas i detect the ground varies significantly. I suppose i will have to experience this myself when in the gold fields.
Yes I am sure it only does it on hot ground a friend has a 10x? razorback it does the same thing .I am going to try the standard coil latter this week see how it goes thanks
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Hi. All. From my experience the hiccup is the same as Roscoe's. Mainly when raising and lowering the coil whilst GBing. I do hear it sometimes while detecting though. Bloody nuisance if you ask me? It's beginning to really bug me! It happens on most ground around Bendigo and surrounds where I live. I'm hanging out Old Hand to see how you go with that pot. If it works, you'll be my best friend. And I suspect everyone else's too who hates this glitch! Whites should've done a bit more work on this to eliminate this noise IMHO.!
I was out this morning with a 14x7 nf I normally like to run the gain at 8 ,when raising and lowering the coil the hiccup dose not worry me as you are GB the detector to start detecting. Started of with gain at 8 but as you say hiccup now and then took the gain back to 7 that was a improvement, on gold 22s, 1 shot pellet that made me happy. The 10 turn pot is coming from china so there postage is slow once I have it fitted I will post the results regards john
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No worries. Will wait to hear your result.
Ok,
I tried a DD coil on a SPP and on a modified SL and here is what I found. On the SPP, the DD worked fine. On the modified SL, If I turned the gain to max, I would get a hiccup, but at about half gain, it worked fine. Now, at max gain I found if I altered the Special noise reduction circuit, I could eliminate the hiccup.
Now, my modified SL has several changes including a special preamp that is faster and supposedly quieter than the factory IC. This special IC is faster and has a rail to rail output. This means the special IC I used will act differently and could cause strange results.
I suspect your SPP is acting differently than most. So, you might want to take it back and check it against another one. If your unit works fine at half gain, then you need to check your half gain depth wise against another SPP half gain and then the other SPP at full gain. Right now, it sounds like you have a unit that has higher gain than most.
There is a single small internal pot inside the SPP and that is marked VR1. This pot is used to calibrate the GB control. So, if your mono coils GB correctly, then most likely the internal control is set right.
Reg
I tried a DD coil on a SPP and on a modified SL and here is what I found. On the SPP, the DD worked fine. On the modified SL, If I turned the gain to max, I would get a hiccup, but at about half gain, it worked fine. Now, at max gain I found if I altered the Special noise reduction circuit, I could eliminate the hiccup.
Now, my modified SL has several changes including a special preamp that is faster and supposedly quieter than the factory IC. This special IC is faster and has a rail to rail output. This means the special IC I used will act differently and could cause strange results.
I suspect your SPP is acting differently than most. So, you might want to take it back and check it against another one. If your unit works fine at half gain, then you need to check your half gain depth wise against another SPP half gain and then the other SPP at full gain. Right now, it sounds like you have a unit that has higher gain than most.
There is a single small internal pot inside the SPP and that is marked VR1. This pot is used to calibrate the GB control. So, if your mono coils GB correctly, then most likely the internal control is set right.
Reg
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Hi. Reg. Don't use a DD at all. Only time was as above which as I said couldn't GB at all. I do run my machine at higher gain than most. Got used to doing this on the ML 4000 I had, and learned to listen through the noise for better gold recovery, which worked for me. I have found the hiccup is still there when running at the marked pos on the dial. Not as much, but still there. Would be nice to eliminate it altogether at any gain. Would make the SPP much nicer to use. Everyone seems to be running other coils on this machine. Nobody seems to be using the one that came with it. Can't understand this really. I have no trouble picking up lead shot with this coil . Only reason I got a Dtech 8" was for looking for tiny gold in tight places .And also for coin detecting when I get around to fitting the conductivity switch. The standard coil seems sensitive and a good match for the SPP with a reasonable cover area too at 12" Regards.... Ronnie.
Not all DD coils are built exactly the same. Some tune the coil for minimal signal in the receive winding while others seem to try to minimize ground signals while tuning.
Now, Roscoe, you said if you reduce the gain, you notice the hiccup goes away. This is what I found on one detector. I also found that detector had more gain than the other I tried. So, when I reduced the gain I lost minimal depth but did lose the hiccup.
There is one more thing you can try to minimize the hiccup but it requires adding a jumper to short out a diode. This may or may not work since I don't know if the hiccup you are experiencing is caused by the radical ground which is nothing like we have over here.
As for the diode to try to short out, it is D21 located by U8:b. You can also short across the capacitor C42, near U12:a. You can simply use a small piece of wire, maybe a 28 awg or 30 awg and attach one end on one side of the parts mentioned and the other end of the wire on the opposite side of the part to be shorted out. If you do this, let us know if it helps.
If you short out D21, you might notice a very slight difference in noise. Normally, this is minimal but at the same time could give you a slight gain in depth. What we found over here is on a US Dime size object we can gain close to an inch in depth in certain areas. Usually, the depth increase is closer to a half inch.
Ronnie,
The reason you might be experiencing more of a problem than the factory ever experienced is the ground conditions you have might be worse than anything we have, which we can't readily simulate. Thus this quirk or its intensity may be native to certain areas where the ground conditions can create it and as such may require less gain to minimize it. I can create a similar situation when I increase the gain via using a different opamp. This extra gain doesn't do anything for depth but does intensify the ground signals. Reducing the gain basically reduces the increase in gain I got from the new opamp and I am back in business.
In your case, the ground signal my be so intense, it simply won't allow you to operate at maximum gain without causing the hiccup you mentioned. The other alternative possibility might be the detector has much more gain than others, thus causing the problem. Unfortunately, increasing the gain more than the standard factory standard mainly adds more noise and other problems with little to no depth increase.
If the ground condition is the problem, I am guessing the location won't allow most ML owners to use mono coils because of GB problems.
Reg
PS: When soldering on a TDI pc board, make sure to use a quality grounded soldering station where the tip is grounded. Static from cheap soldering pencils can cause damage.
Now, Roscoe, you said if you reduce the gain, you notice the hiccup goes away. This is what I found on one detector. I also found that detector had more gain than the other I tried. So, when I reduced the gain I lost minimal depth but did lose the hiccup.
There is one more thing you can try to minimize the hiccup but it requires adding a jumper to short out a diode. This may or may not work since I don't know if the hiccup you are experiencing is caused by the radical ground which is nothing like we have over here.
As for the diode to try to short out, it is D21 located by U8:b. You can also short across the capacitor C42, near U12:a. You can simply use a small piece of wire, maybe a 28 awg or 30 awg and attach one end on one side of the parts mentioned and the other end of the wire on the opposite side of the part to be shorted out. If you do this, let us know if it helps.
If you short out D21, you might notice a very slight difference in noise. Normally, this is minimal but at the same time could give you a slight gain in depth. What we found over here is on a US Dime size object we can gain close to an inch in depth in certain areas. Usually, the depth increase is closer to a half inch.
Ronnie,
The reason you might be experiencing more of a problem than the factory ever experienced is the ground conditions you have might be worse than anything we have, which we can't readily simulate. Thus this quirk or its intensity may be native to certain areas where the ground conditions can create it and as such may require less gain to minimize it. I can create a similar situation when I increase the gain via using a different opamp. This extra gain doesn't do anything for depth but does intensify the ground signals. Reducing the gain basically reduces the increase in gain I got from the new opamp and I am back in business.
In your case, the ground signal my be so intense, it simply won't allow you to operate at maximum gain without causing the hiccup you mentioned. The other alternative possibility might be the detector has much more gain than others, thus causing the problem. Unfortunately, increasing the gain more than the standard factory standard mainly adds more noise and other problems with little to no depth increase.
If the ground condition is the problem, I am guessing the location won't allow most ML owners to use mono coils because of GB problems.
Reg
PS: When soldering on a TDI pc board, make sure to use a quality grounded soldering station where the tip is grounded. Static from cheap soldering pencils can cause damage.
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Hi. Reg. Before this machine I had a ML GPX4000. Same areas. Absolutely no problems, and I was running the gain at around 13 which I found got me more gold. Standard gain recommended for the 4000 was around 7. When it did play up usually a quick bounce with the fast track button depressed sorted it. Had a little bit of noise but learned to listen through it. The problem I find with the SPP is mainly in the ground balancing as I have said before. The window between the high and low balancing tone when turning the balance knob is so tight that you need to turn it so much of a fraction each way that IMHO it is the most difficult operation to perform on this machine. It seems to really need a fine adjustment control to address this problem. My friend just bought an SPP last week and comparing the two, they are the same. Same hiccuping and same tight GB setting. Having said all that the hiccuping is not really having an effect on the ability of the machine. If a target is in the ground, even a shotgun pellet you will still hear it. For me it is mainly an annoyance issue, and I am still surprised that a bit more work on the circuit design couldn't have fixed it when whites built it. It's a pity, because apart from these issues it is a little gem of a machine. From all other points of view it is nice to use. Regards....Ronnie.
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Ronnie I'll meet up with you somewhere in the next few weeks and show you a few razorback coils I'm sure they will fix all the problems you are having.
Hi sorry to say the small razor back that I had a lend of from another member did it to .
Ronnie,
Keep in mind the SPP was not designed for OZ soil and the SL which is the same design is not sold there. Part of the reason for this is it had never been fully tried there before. With OZ having some of the worst soil in the world, more experimenting and design changes really should be done. However, the SPP is being sold at a very low price and probably should have been sold with the knowledge some quirks might show up.
I have to take some of the blame for the hiccup since it appears to be enhanced by the noise reduction design, and that is partially my design.
The original TDI had a slight hiccup that was minimized by fooling with the blanking design that eliminates the second half of the signal so you only hear the wee or the woo.
Unfortunately, that design is speed dependent and can be altered slightly by too fast or slow of a sweep speed. Furthermore, the noise reduction makes this feature even more temperamental. To eliminate or further reduce this hiccup would most likely require a total redesign of the SL circuitry but since the sales are just not there, it was not redesigned and engineering time was spent on more lucrative coil hunting machines.
I have done some work and tried a few other things but never really spent much time on the problem since the problem is minimal over here.
I am guessing if the gain was reduced to the level where the hiccup is minimal, I suspect the actual depth loss would also be minimal. Hopefully, when Luke comes to where you are and if he has similar results, he will run some simple tests for me, including reducing the gain to the level to remove the hiccup and then check depth on small nuggets and compare that to maximum gain with the hiccup.
In the mean time, I will try some rather unique ideas I have to enhance small gold signals.
Reg
PS: Your previous machine, the 4000 when new cost dramatically more than the little SPP does new, so I would expect it to work better. However, I will continue to work on ideas to further enhance the SPP. In the mean time, it is a really durable detector.
One other note, on the SPP, I think you will find the GB pot is a 10K. So, adding a 500 ohm or a 1k in series with the present GB pot will give you a decent vernier control.
Keep in mind the SPP was not designed for OZ soil and the SL which is the same design is not sold there. Part of the reason for this is it had never been fully tried there before. With OZ having some of the worst soil in the world, more experimenting and design changes really should be done. However, the SPP is being sold at a very low price and probably should have been sold with the knowledge some quirks might show up.
I have to take some of the blame for the hiccup since it appears to be enhanced by the noise reduction design, and that is partially my design.
The original TDI had a slight hiccup that was minimized by fooling with the blanking design that eliminates the second half of the signal so you only hear the wee or the woo.
Unfortunately, that design is speed dependent and can be altered slightly by too fast or slow of a sweep speed. Furthermore, the noise reduction makes this feature even more temperamental. To eliminate or further reduce this hiccup would most likely require a total redesign of the SL circuitry but since the sales are just not there, it was not redesigned and engineering time was spent on more lucrative coil hunting machines.
I have done some work and tried a few other things but never really spent much time on the problem since the problem is minimal over here.
I am guessing if the gain was reduced to the level where the hiccup is minimal, I suspect the actual depth loss would also be minimal. Hopefully, when Luke comes to where you are and if he has similar results, he will run some simple tests for me, including reducing the gain to the level to remove the hiccup and then check depth on small nuggets and compare that to maximum gain with the hiccup.
In the mean time, I will try some rather unique ideas I have to enhance small gold signals.
Reg
PS: Your previous machine, the 4000 when new cost dramatically more than the little SPP does new, so I would expect it to work better. However, I will continue to work on ideas to further enhance the SPP. In the mean time, it is a really durable detector.
One other note, on the SPP, I think you will find the GB pot is a 10K. So, adding a 500 ohm or a 1k in series with the present GB pot will give you a decent vernier control.
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Hi. Reg. And Zuke. Thanks for the info Reg. Old Hand is working on a vernier pot fix above so hopefully he will be successful with that. Your right of course re. GPX4000. You do get what you pay for. Hopefully you and others might find an answer to the little hiccup.Maybe a simple fix will show itself. We can live in hope. I will as you suggest though run with less gain and hopefully won't lose precious depth. And Zuke. Am looking forward to meeting with you sometime soon. Maybe between you and John and Reg and anyone else who gets involved we'll tweak a bit more magic from this little machine. All the best to all...Regards...Ronnie.
KarlS
Karl
I have spent three days on my sister's property around Kandos. One day was dedicated to detecting. As expected I haven't found any gold, just usual junk. But did spend couple hours testing SPP. Now I understand what Ronnie and Old hand are complaining about. I selected spot close to the river that had mixture of soil and river wash. The X-terra 705 ground balanced there at 15. That is not very mineralized ground. The SPP with 7,5 inch TDI OZ mono coil and all the knobs in default position GB at 8. The targets 1 cent coin, 2.5 grams aluminium nugget and 6 grams lead buried 9 inches could be just heard. I then switched to Commander 10x5 DD coil. GB was problematic and best possible balance was right on the end of the scale. The targets could be heard much clearer and signal was less noisy. But if you did not kept coil at constant height above ground it would squeak, or hiccup often. Just to try something, I changed battery pack for one that outputs 12.6 volts, but could not see any noticeable difference in GB.
I think that cap mod that Reg mentioned is really necessary because on occasions when you change distance between the coil and ground quickly, detector starts squealing. I also think that to use DD coils Ground Balance range needs to be increased. Adding 1K pot in series to existing GB pot should increase GB range and also provide fine tuning. The diode mod is also interesting. But it means to drill two holes in detector box and definitely void the warranty. I will think about it
The trip was not completely wasted, I had picked two fist sized pieces of quartz that gave small but noticible change in threshold. Now home and with aid of magnifying glass I can see few tiny specs of gold or pyrite in it.
Karl
I think that cap mod that Reg mentioned is really necessary because on occasions when you change distance between the coil and ground quickly, detector starts squealing. I also think that to use DD coils Ground Balance range needs to be increased. Adding 1K pot in series to existing GB pot should increase GB range and also provide fine tuning. The diode mod is also interesting. But it means to drill two holes in detector box and definitely void the warranty. I will think about it
The trip was not completely wasted, I had picked two fist sized pieces of quartz that gave small but noticible change in threshold. Now home and with aid of magnifying glass I can see few tiny specs of gold or pyrite in it.
Karl
