More Frequencies on the 2100?

Hi Ismael how have you been, Ive got a couple questions that I think your the guy to ask. I was talking with a friend the other day about changing frequencies on a minelab 2100. He stated that Minelab included two sets of crystals on every 2000 and 2100 and that anyone can change between the two by just moving a jumper located on the circuit board. Have you heard of this? If so why wouldn't it be possible to combine them both with a jumper and have four frequencies? Is this possible? or would they need a switch like you talked about in your mod.Thanks for your time and Merry Christmas. AzNuggetBob

Well Bob from your photo shots you have now posted in the infamous thread \"Full m/lab SD2000 schematics\" you have indeed achieved your 4 frequency mod. The photos shots look great so goodonya.

I see the fella from Oz who started this infamous thread with the 2000's schematics is curious as to what your mod is capable of.

Bob I reckon you made a good point in your last reply to me in the other thread that due to the 4 freq. onboard the 2100, more depth on bigger nuggets and higher sensitivity to smaller nuggets and could explain why some 2100's work better than others in different situations. Bob I have posted previously that there were tests that showed large variations in performance of 2100s with some more sensitive to small targets while others best on larger targets with more depth. Your reasoning may well be right.

Also Woody is having success doing more mods for the 2000 and from his last reply to the thread in question, is doing mods for the 2100 also.

Keep up the good work and hopefully your mods to the 2100 can snagg missed gold for you.

Cheers,
Gaz.

G`day guys,first post today,g`day Ismael you still about.
Yes Gary AzNuggetBob mod is an interesting one,he mentions crystal on 2100 but on the pic i have of the 2100 i dont see any but i do see the jumpers,i am just a winny curious as to what he did,maybe he doesnt wanne tell me.

Zed

Hi Zed, I will try to explain what I did to my 2100. BTW I posted the pictures of the mod over there on Geotech in protest of minelabs (At the time of my posting) indecision on moding and openly sharing information. Anyway It would appear that minelab changed the transmitting system by no longer using the crystal can type transmit system they used in the 2000. I did some checking and it appears they switched to a VCO in the 2100. Although I have not yet identified the exact make or model yet because they ground off the factory I.D. markings. I also noticed that they kept the frequency change by jumper move they have on the 2000 but now it is times two, having 4 frequencies to choose between. There are 6 pins in the jumper setting, two sets of three with the center pin in each three being common and the outer pins being separate frequencies. I don't have an oscilloscope any longer and I don't know any other way to verify the exact frequencies being transmitted. I suspect the frequencies only differ slightly as this is all that is needed to stop cross interference with other near by minelab detectors and that is why minelab kept this option. I do think this is at least one of the reasons some 2100 perform slightly better than others. So basically all I did was add two on/on toggle switches to the control box face plate moving the ability to change the jumpers from the inside to the outside. Its that simple. I hope this explanation is clear. Take care all AzNuggetBob

I consider this mod experimental. Attempt it at your own risk! I assume no responsibility.

Note: I also found out that according to the factory specifications of these VCO chips the frequency range can be changed slightly (adjusted) by simply adding or subtracting a volt or two to the VCO chip.

Something else to consider is that there may be problems with parasitic capacitance and inductance because of the longer leads and resistance in the switches. any ideas on this Zed. AzNuggetBob

G`day Bob,thanks for the swift reply,i havent seen anyone mod a 2100 before so my curiousity was a little up as to what you did,thanks for sharing the details,its a pity you dont have your scope any more, a person can do lotsa work with a scope,no matter.
If you have the right multimeter you would be able to measure the frequency the detector was running at,some DMM have a function for measuring frequency.
On my 2200 they use a similer setup and i used to change the frequecy by changing the value of a smd capacitor,
the range would go from 1.5 meg upto 4 meg,it was fun to play with.
The results were mixed but there were improvements in some areas,ultimatly you would need to remove the paint around the cct and trace out out the tracks and components to get an understanding of what is going on and
go from there but a scope is essential so as to make sure you are getting a proper wave form.
The parisites that you refer to are every where in a cct,in your case you would need a scope just to make sure but if your happy with the way your detector is running then i wouldnt be to concerned.

Zed