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PostPosted: Sat Jan 14, 2012 8:42 am 
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Joined: Fri Jan 06, 2012 12:28 am
Posts: 7
Would buying a unit made 7 years ago be a wise choice? Do they last forever? What fails most likely if there's a problem? Would the whole unit have to be shipped back for repair (if they'd repair it) or would they send you a new circuit board or whatever component has failed.

Considering unit SIR-3000.


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PostPosted: Mon Jan 16, 2012 6:26 am 
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Joined: Wed Apr 29, 2009 5:52 am
Posts: 96
Location: Zagreb, Croatia
Dear generalzod,
although GPR units are quite sturdy and long lasting (I've seen units >15 years old still in use) it is all a question of how they were treated (mechanical damage to the casing and contacts). One thing that you should check is the batteries - rechargeable batteries. If the unit was used/stocked in a harsh environment (heat/cold) or used very often perhaps the recharge cycles are used. Contact the manufacturer to see what would be the price for the new ones (or if you can get a replacement pack somewhere else) and see if the possible price for the new batteries+price for the used unit is near to the price of the new unit. It would also be wise to see if the seller is offering any warranty so you have a chance to test the equipment - just in case.
BR

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"If the only tool you have is a hammer, you will see every problem as a nail."


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PostPosted: Mon Jan 16, 2012 8:48 am 
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Joined: Fri Apr 17, 2009 7:52 am
Posts: 379
Location: Boden, Sweden
Hi generalzod,
Since you mentioned in some other topic that you are an EE professional then I guess you
can imagine that a precise timing instrument like a GPR would need some sort of calibration
after three years of use max, leave alone 5 - 10 years. We offer a free calibration to all our
units during the warranty period, three (3) years from the date of purchase. So, if you are
buying a used equipment do ask for the age and if it has been calibrated in the past two
years. There is a wide spread opinion that GPR units do not require calibration, but that's just an
opinion not supported by anything. Any measurement equipment does require
calibration for you to know what you are measuring, specially if you are dealing with small
ranges such as 6 - 10ns. The self-calibrating routines found in many commercial GPR units
are short term measures and do not compensate for long term changes in the unit itself.
Electronic devices such as clocks do change their properties with time, in the units using
analog timing generators, and yes, there are still plenty of those, the timing capacitor also
will change with time and therefore corrections need to be made to ensure proper use of
the unit.
Best regards,

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Reinaldo Alvarez Cabrera
Geoscanners AB
Sweden
http://www.geoscanners.com


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PostPosted: Fri Mar 30, 2012 7:42 am 
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Joined: Fri Mar 30, 2012 7:20 am
Posts: 6
We have a unit that is more than 10 years old now and it still works perfectly. Despite the hard use it seems a survivor. But this is not the case always. As the other guys told you it is a matter of use, weather and work conditions and of course luck. It is like buying a second hand car, even if you buy a Mercedes nobody can guarantee to you that it will last forever.

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Geomorph Instruments,
Your reliable GPR Supplier
http://www.gmradar.com


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