chargers by the biggest one you can afford! low impedance chargers are the only way to go!! jewels are the measurement of stored energy on the wire the higher the jewels the more bite the fence will have!!!!high impedance chargers (weed burners) are a joke DO NOT PURCHASE ONE!!!! if some one gives you one, put it in a yard sale!!!!Cyclopes by Taylor (USA) is what i have now 30 jules on the wire loaded! Pell makes a good charger Gallagher also makes a great charger as well!!!!! both are out of new Zealand they do high tensile fence right !!!! i think the site is
www.kencove.com sells wire and droppers, strainer, etc etc ... but the most important thing they sell is a little book on the proper way to build high tensile fencing by the book before you buy any thing else hope this helps post script i build fences and our entire farm is high tensile wire!! don't cut corners! DIGETAL fence testers is the only way to go!
this is a 20 Jule Cyclopes made by Taylor of Arkansas! a ground rod drove 8 foot in the ground covers a 16 foot circle! so a ground rod every 16 feet hooked in sequence is a heck of an ANTENNA (5 rods 16 foot apart ) gives every one a reason to stay in the pasture !!!!
http://www.youtube.com/watch?v=EhKd_VJ1t7Y