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I'm looking at replacing the crystals on my sd2000 I'm not worried about a 4 crystal mod I just want to put lower MHz ones in ...i could have anything between 1.8 and 2.2 in as standard .... looking online I can only find 1 MHz and 1.843 MHz ...I used to own an sd2000 that Ismael fitted a vco for me but as he doesn't do this anymore I'm looking at doing some mods myself..... question 1. Anyone know if and where other xtals are available say 1.25 or 1.5...also does the of rating make a difference as I noticed some with capacitors. I don't claim to know much about electronics but capable of soldering
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Meant PF not of rating -
I don't know much about electronics either but I did recently build an SD2000 based on a schematic that's posted here. The drawing shows a 2.1 MHZ crystal as standard. While the factory units have 2 crystals, only one is used. The second was for use where 2 units would be used in close proximity to prevent interference. The dealers where equipped to change them. I don't know the value of the second crystal.
After doing a lot of reading, the consensus seems to be that the ideal frequency range for the SD2000 is between 1.8 and 3.0 MHZ. I used 4 crystals in mine starting with 1.8 and incrementing up to 3 MHZ. Using a ML mono coil I'm very happy with the results. I couldn't find a crystal between 1 MHZ and 1.8MHZ online either. Although looking in my junk box I did find a 1.6MHZ.
It would probably be simple to wire your existing 2 crystals using a double pole switch to change between the 2 you have. I used 2 - 18pf capacitors that run either crystal.
The Aussies are the experts on these things and check here from time to time.Comment
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Depending on your electronic skills, this thread may be interesting.
http://www.geotech1.com/forums/showt...ghlight=sd2200
add: pre built
https://www.ebay.com/itm/AD9850-6-Ba...gVj-:rk:9:pf:0
with rotary encoder
https://www.ebay.com/itm/8MHz-DDS-Fu....c100005.m1851Comment
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Thanks guys ...as I said I have little electronics knowledge .this is my third sd2000 the first I bought had dodgy mods done before it came into my possession and Ismael fixed it and added vco at a fair price ..but I sadly had to sell it ...my next sd2000 was given to me not working ..someone had had it apart and stuffed it ....I sent it off to woody who said it could not be repaired so I said keep it if was any good for parts or whatever....I recently got one off eBay that is in original condition ...with Ismael not modding anymore I contacted woody ...i think it was his son Dave who quoted me $1500 for a full mod ....now I have met woody and have nothing bad to say about him...he is just trying to make a living like all of us ...but there is a heap of info Ismael and even woody himself has put online on DIY mods. Change a few fets ...GPM mod and upgrade the lm394 and xtals ... there could be more I don't know of but I figure even if pay someone with expert soldering experience to fit parts for me it would be nowhere near $1500 ...the most expensive part is the mat12 at around $45 ....the only part that my be beyond my soldering skill is the GPM mod as those pads are very small and my fingers very fat. But I'm not trying to put woody or his business down for overcharging as I don't know the full details of what he changes but I reckon anyone who is game to modify detector s worth many thousands of dollars is entitled to charge whatever people will payComment
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I wouldn't worry about the MAT12 ..was the first to use this I reckon many years ago .... not much of improvement with thatComment
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