Until recently the modifications available to the Minelab range of Pulse Induction detectors were only giving a small gain in sensitivity and depth. The newest collection of modifications greatly improve all of the Minelab range from the SD-2100 SD-2200 GP Extreme GP-3000 GP-3500 GPX-4000 and all the way to the GPX-4500.

We have found that some Minelab detectors do not work very well with certain types of coils. This can be greatly improved by using the Variable Coil Dampening mod. This mod dampens the coil ringing that occurs after switch off. If the coil is under damped the ringing will cause the detector to very noisy in operation.

The Pulse timing modifications can increase the sensitivity and depth and also greatly reduce the response to Hot Rocks when in the Deep timing position. The Sensitive position is fantastic to pull specimens from Mullock heaps. The Medium or General prospecting Mode is an all round detection setting that covers all bases.
The Sensitive position brings the receiver timing closer to the end of the Transmit pulse and will find the hard to detect Gold with fast time decay properties such as Reef break, Spurry Gold or filament types of Gold.

The Other Pulse positioning mod can give a SD series detector timings similar to the GP series of detectors.
This same modification when applied to a GP series detector can give the most substantial depth and sensitivity increase that I have ever seen. When tested on a GP-Extreme the detection depth was far more than a GPX-4500.
To get the same depth with a GPX-4500 we had to crank up the gain so high that the detector was so unstable we could not use it to prospect. When the stabilizer was used we could no longer detect the target.  That is not to say that the GPX-4500 is not a bad detector, it sure is a great detector but it only goes to prove that all these detectors can be improved. If that was not true we would all still be using the SD-2000.

The other modifications that are available include the addition of Soft Recovery Diodes in the transmitter power stage to reduce noise, also some detectors in the GP series are missing an add on that was connected to the transmitter stage. If this is missing we add it in.

One Major modification is the addition of Low ESR capacitors to crucial stages of the detector to reduce noise that is generated inside the detectors by its own switch mode power supplies. This can cause noise in the amplifier stages of the detector and cause noise that masks some low level target signals. I have had around 20 years developing switch mode power supplies and am very experienced to update this part of the detector electronics.