There are two laser rangers which can be used for the DistoX.
Disto A3 - best option
Stabila LE50 - a bit tighter fit because there is more internal plastic, this is a rebadged A3. A UK company is still selling these new.
http://www.ahc-camberley.co.uk/catalog/ ... s_id=12469Some have suggested the Stanley TLM200 but I would suggest you not bother with this. It has much reduced functionality and is only capable of 30m.
Ebay is the obvious place for a Disto A3 and you could broaden your search to include the UK, Ireland, Germany etc. ebay sites.
Gumtree and Craigs List are alternatives.
Another place to try are the Leica Geosystems Disto distributors. Look for any that hire out instruments or if they offer trade-ins. They may have a Disto A3 or know some customers with one.
As to the DistoX upgrade. The process involves replacing a few screws and lead-free soldering four wires with standard precautions about electrostatic discharge and electronic board handling.
Calibration is key to DistoX performance - it is a sensitive magnetometer. Calibration is done on your Bluetooth equipped PC or PDA running the PocketTopo application in an electromagnetic quiet zone, cave, empty field, forest etc.
Lithium one-use batteries provide the longest life and these need to be packed in place with wadding to avoid movement. New batteries must be calibrated.
Alternatively there are ZnCl low magnetic signature batteries which can be used but will only last for about 100 measurements before running out. Martin Sluka reports that a new calibration is not required.
Lots of great documentation on DistoX and PocketTopo at
http://paperless.bheeb.ch/