SD2200d frequency mod?

Hi guys, it's me again.

Firstly, I am quite happy with my 2200. Although I recon I would be happier with a GPX, I'm not quite there yet
With the tests that I have done, I have come to realise that with the DD coils, I loose sensitivity with the larger coils. Although I always knew this, I am a little surprised that the sensitivity loss that I get when using my 14"DD Elite. Half grammers and below, must virtually be scrubbing the coil to get a reaction. A couple of inches down in the soil and I pretty much have no hope of hearing them. The 11"DD is more sensitive and the little Joey DD picks them well but of course looses a cosiderable amount of depth. Quite different to using monos where you loose pinpointing ability with the larger coils but you still have overall sensitivity even with the very tiny subbies. So with DD coils, I must decide before switching the detector on, how deep the ground is and the potential size of the nuggets in the area and then put on the appropriate coil.

I know some of the 2000s and the 2100s had a frequency mod performed and generally position 4 increased the frequency to 3.0MHz, which made them more sensitive to the smaller bits with a little sacrafice to the depth. Does anyone know if it is possible to be done to the 2200d, seeing as it doesn't use frequency crystals? If so, does anyone know what is involved and maybe who could carry out such a task? Or is it a fairly straightforward mod that someone like me, that is capable with a soldering iron and knows the difference between my capacitors and resistors can do? I presume Link can do it, but does anyone know anyone else that maybe is a little bit more approachable and can maybe speak in a language that I may understand and discuss my options with? Ismael Jones would be from all I've heard, the perfect person for this, but I have heard he no longer does this sort of thing....pity.

Thanks all............

Hi CD,

Just wondering why you don't use mono coils? I pretty much only run mono coils and any time I do try a DD I just don't like it. One little mod that can be done is a switch to turn a DD coil into a mono coil. It will transmit and receive off only the left side of the coil. It will be a lot more sensitive and if the ground gets too noisy you can just switch back to DD. This can also be done with a small plug that goes between the coil and detector.

As far as the mod you speak of goes, yes there is a way to alter the clock speed but it is best if you have a scope to confirm what is going on and that everything else is still working as it should. Also when working with the ML boards you need to be extremely careful when removing parts that you don't damage the board. It would also be good to check the rest of the detector out first to make sure there are not other problems that need to be rectified. Also be aware that ML will not repair or service a modified detector however I don't know how keen they are to do the old sd's any more(please confirm this with ML) If ML won't repair it, I will!


Cheers Mick

Hi Mick, and thank you very much for your response.
As far as adjusting the clock speed, I do have a CRO but it has been quite some time since I've used it and even then I wasn't up to speed with my abilities in this field. I would like to have the ability to flick up the frequency and then flick back to standard when I choose, like what is possible with the 2000s & 2100s, but I don't want to risk my machines present abilities to achieve this and especially when not having even a schmatic to work with. I suppose I'll just have to concentrate just that little bit harder for those faint signals when I'm out there and keep saving my pennies to put towards a GPX.
In answer to your question re why I don't use mono coils, I have found them extremely noisy on my SD machine during my trials. Even this last weekend I tried once again using a NF SL 16" mono that I still have, and I found that with the continual waviness of noise, I was retracing my steps constantly and second guessing every sound. Because on the SD I don't have the ability to adjust filters, gain etc, I don't have the ability to quieten it down and I cant tolerate all that noise. Mind you I am using a 7.3v system and it has been suggested that if I use a standard 6v battery, it may become quieter, but I have not tested this theory as my standard dome top battery is completely unchargably dead. I know oher peoiple can put up with it, I also know my shortfall is that I can't unfortunately. I do like your suggstion about the flickswitch re converting the DD to a mono temporarily though. I can definitely advantages and situations that that would be helpful. Do you have a link to a schemaic diagram for this project?
Many thanks once again.

Hi CostasDee,

Mick was the one who mod my SD2000 and it worked very well . ( with so many frequencies to choose from in order to quiet down the EMI and also the type of nugget you are looking for). I fetched over half kilo of nuggets and specimen from his machine.

I think he can mod your sd 2200 as well . ( probably 50% less than other will charge u )

Cheers,