I thought it was about time that I described the mods that we perform on the 2100 and 2200 detectors and what they do.SD2100 Modifications...
The modifications to this detector are similar to the GPM mods on the 2000 and work exactly the same.
The control below is the combination power and frequency select . The positions are (from top rotating clockwise),
1 - On Standard Frequency,
2 Frequency similar to 3rd frequency on sd2000 frequency (Higher)
3 Frequency similar to 4th frequency on sd2000 (Highest)
All of these frequencies will give sensitivity gains on targets. Used in conjunction with the tune control you can select a quiet frequency and also a stable threshold as with the VCO on the SD2000.
Again these two controls are the exact same modification as the GPM on the sd2000. Looking at the picture the right most control is channel 1 and the left most channel 2. These increase the detectors receive gain and as such increase overall performance. As with the 2000 you will have to trial these to get the best gains. As a rule I suggest that you use a large test target of around 5gms and after balancing the detector as normal set the balance switch into each position (1 & 2) whilst adjusting the control corresponding with the selected position and testing over the test target for best response.
The pros are obvious the cons are that you may find an increase of ground noise and also run out of ground balance, mostly with channel 2.
The 2200 can have quite a few modifications that greatly enhance its performance. The detector in the pictures is my own which is for sale. I am only asking $2600 which is quite good considering its ability (see forum post "Field Tests" for results.
Starting from the top is a rotary switch for selecting frequencies the same as the 2000/2100 except it uses the inbuilt VCO to select frequencies. Next down is an extra switch to turn the detector on and off as these detectors can lock up when trying a combination switch as in the 2000/2100. The extra frequencies really give the 2200 an edge especially when going up in frequency. I have seen deeper results from faster frequencies which is the opposite to the 2000 and the gain is considerable. All other switches are the same until the one near the boost switch. This addidtion selects different timings inbuilt into the detector but are not selectable by the user. I'd imagine that ML was already preparing for the mode select featured in the GP series (sensitive, normal and salt). They do not work that way but each setting has it's own ability to detect different target sizes and change the detecting parameters. The settings do improve performance. The middle setting is normal. The next switch (near the ML Logo) selects another mod that increases sensitivity and can null out some hot rocks and being more sensitive and deeper on small gold.
The only mod on this side is the Gain control. This acts similar to the GPM on the 2000 with the only difference is there is only one control that works on all channels which makes it more simple to use and the gain id significant. The major difference with this gain and the GPM is the amount of turn gives a lot more sensitive and therefore needs very little adjustment. By this I mean a turn of 1/8 can increase sensitivity a lot so care needs to be taken when using this otherwise you can increase gain to the point of the machine being hard to GB and noisier than usual. Overall, as you can see by the results in the forum post it gives a significant increase in depth and sensitivity. There are 2 other mods I can perform to this but as yet have decided not to, they are a socket for a tracking button on the handgrip like the 3500 and a manual tune also like the 3500. All detectors from the 2200 up can have these mods.
Well at the moment that is about it. The instruction manuals for these 2 modified detectors are in the download area.