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Messages - woody

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76
The extra add on's are $450 for extra long pulse and VF if not on the detector, a input preamp upgrade can be carried out at the same time and that takes it to $650.

There are lots of complicated mods but I only do them on specific requests if you need the detector to get specific gold in specific hot ground.

77
Only the DD has a resistor across the receive winding, 1K ohm

78
Technical / Re: SDC2300 coil specs
« on: August 01, 2017, 12:47:43 am »
The SDC works with any ML coil for P.I , I installed a 12" Nugget finder on a SDC2300 and it worked perfectly.

79
General Discussion / Re: Wanting to upgrade my GP Extreme
« on: May 27, 2017, 09:09:29 am »
Hi Jud,  does your email still work?  Been trying to contact you as your detector is ready.

80
The older units can only be pushed so far but gp extreme and up is very much a decent improvement. The older units like the sd series can be improved but the later detectors are more versatile.

81
General Discussion / Re: Detector Coil
« on: May 24, 2017, 10:49:29 pm »
I have made some coils over the years, i wish that i still had them but other prospectors wanted to give them a go so if i ever get around to firing the vacuum former again i will make up some more.

82
General Discussion / Re: Detector Coil
« on: May 24, 2017, 10:42:30 pm »
Hi Ron,

I bought one of the Detech 10 x 15 mono coils , it can pull a 14 gram at 16 inches in hot coil.  Nenad has them or Stinky Pete at Detech in Daisy hill in victoria.

For $340 they are a good light coil, i used it all day continuos swinging and it was easy ..

83
General Discussion / Re: Detector Coil
« on: May 24, 2017, 10:17:40 am »
Im not sure if Carbon coils is still in business making coils.  Still most manufacturers of coils are still making one huge mistake with the coil designs..

84
As of today I have done 2 test detectors with the newer components installed on brand new boards.   
These are operating with outstanding performance, it definitely makes me want to get out and go over old ground.
These new parts have internal interference filtering that seems not to affect the noise figure and stability of the detector.
Operation is rock solid even running close to full gain.

85
General Discussion / Re: modded GP3000 settings
« on: April 27, 2017, 06:50:37 pm »
The trick to getting the best performance is to start the detector with the frequency control full clockwise, this allows the internal electronics (PLL) oscillator to lock over all of the adjustments using the variable frequency. If you start the detector with the detector frequency control not set to maximum clockwise the detector could go out of locking for the internal oscillator and the detector will either make crazy chirp noises or make bwarp bwarp noises.
If it goes crazy just switch it off and set the frequency to full clockwise and start again.

The frequency control when turned clockwise sets the detector for very tiny gold, the anti clockwise is for larger deeper gold,  set the frequency in mind with the coil size that you will be using, do not go using a 25" coil in high frequency as you will lose depth on bigger gold.  Rule of thumb..... Small gold = small coil = high frequency.    Large coil = larger deeper gold = lower frequencies..     Set the gain to half way (roughly) and ground balance the detector, then move the coil like you are detecting and take notice of the ground noise.. If there is none then increase the gain and set it to the point that ground noise just starts to appear.  Always reground balance after adjusting gain of frequency.

A useful tip, lowering the frequency will reduce ground noise as the ground signal has longer to decay, the upside is that by doing this you can use much more gain to compensate and still have a huge advantage in noisey ground.

Pulse induction detectors have great difficulty detecting specimen type gold, try a very small coil with the high frequency to be able to detect quartz veins..   There is also an advantage in using DD coils and upping the gain for a better signal in relation to ground noise response.

86
General Discussion / If you cannot join the forum..
« on: April 17, 2017, 12:50:05 pm »
We had some issues with the anti spam system , we are told it has been fixed.. So try joining up.

87
There seems to be a lot of new components being made available that can be used to replace components in old detectors to massively improve the performance, we have been in the lab trying out these new parts and some of the results are mind blowing to say the least.... more to come.

One of the most annoying problems using a P.I detector is that they seem to suffer from a lot of interference, well some new devices have been made available that have anti emissions filters built in, I have tried some of these components and noticed an increase in target response at the same time having a quieter more stabile detector. 

88
Some more refinements, I have a GPX-4500 sitting on the work bench at full gain running a mono coil and the detector is just about dead silent except for a very small amount of 50 hz EMI from mains electric cables. small gold performance is exceptional and large deep target response is way beyond anything that i have seen before. I was thinking that removing the high frequency signal component would screw up the ground balance but this is not the case, ground balance is exceptional. this detector upgrade will be the one to beat. As a side note to anyone experimenting with detector input circuit design, any type of diode in the receiver path used as a a clamp or speed up setup on an opamp can cause serious intermodulation from mixing unwanted signals with the dv/dt of the input switching, once it occurs it is near impossible to remove, some soft knee fast recovery diodes can be substituted but its not the be all end all cure, dc servo steering of response time and also keeping dc offset and drift to tight specifications using chopper stabilised servo control has merits, just need to be careful in filtering out any feed through clock noise such that can be observed in the LT choppers in some detectors that i have inspected, a simple 10 ohm resistor and 3300pf capacitor removes most of the noise at some small expense to THD and common mode rejection. When dealing with nanovolt signal levels there is now scope for greater improvement in the signal to noise levels, the limiting factor is still in the input series Fets that can gate modulate the the input signal and resistive and capacitive losses and stray coupling on the input circuit.  All these improvements will get more gold, that is 100% for sure.

89
Mods and Price list / Price list and mod info
« on: February 28, 2017, 10:34:19 am »
Price list for upgrades.

The upgrades start at $250 and go up to $2200, all upgrades carry a 5 year warranty.
If there is any problem with your Minelab in the  future we can repair it, we work on Minelab detectors all day long.  Experience is 30 years electronic engineering, 18 years repairing and upgrading Minelab detectors.

We can upgrade the following detectors,

SD2000, SD2100, SD2200 GP Extreme, GP3000, GP3500, GPX4000, GPX4500, GPX4800, GPX5000.

We have done some work on the SDC2300 and the GPZ7000 but have found the design platform is too difficult and too time consuming to work with, when we upgrade the GP and GPX series detectors we have found superior depth and small gold performance than the SDC and GPZ.
As an example, an upgraded and fully modified GPX4500 will detect deeper than the GPZ7000 and will also detect smaller gold deeper than a SDC2300.

 We have carried out testing and found that we can beat these newer detectors in most types of ground. The SDC will detect the most tiny gold, I refer to this as time wasting Gold, spending 10 minutes looking for a fly speck of gold is not prospecting, you are far better off getting half gram or larger bits. Trying to sift out fly specks robs you of productive swinging time and will reduce your chances of shining the coil over a larger piece of gold.

All detectors can have increased performance by replacing the input Field Effect transistors with lower loss types that have recently become available.

The SD2100 to the GPX5000 can have variable frequency added, this makes a very big difference in regards to the size of the gold, the depth and type of coil that you are using.

All detectors can have a variable gain board added that greatly increases the sensitivity and also allows for correct ground mineral reduction so that gold targets can be distinguished in noise ground or in noisy electrical environments. The minelab gain on the GPX does not work the same way as our gain, matching the input stage to the ground is critical to hearing the targets that standard detectors miss.

The upgrades that we carry out allow for optimisation of coil size, ground type and depth.

Our modifications and upgrades allow the operator to be able to control the detector to best suit the multitude of variables so that more gold is won in the field.

The full upgrades on a SD detector $1500 , on a GP is $1800 and GPX is $2200 and all come with a 5 year warranty that is fully transferable. Newest upgrades (mods) include the deep gold low frequency mode that makes a huge difference to being able to find big deep gold in the most noisy ground.

We can just do smaller upgrades starting at $650 but we find that most prospectors want the best and go for the full upgrades.

When these upgrades are carried out it is like using a newer more modern detector, in just about every case our customers have gone over old ground and pulled out more gold after the upgrades.
Yes, I have also pulled out more gold from area’s that have been detected over by lesser technology.

90
How to repair faulty detectors / Can you trust your detector coil?
« on: February 22, 2017, 07:37:46 pm »
Found a couple of issues with coils, might pay to check them out.

https://www.youtube.com/watch?v=WfUxkfj1b7Y

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