Years of trouble with the oval coil..the batteries been changed and it won’t show the fully charged flash ,butit seems to be fully charged ,so I have given up on it and just use it.bad design somewhere inthe coil
Oval coil is my favourite as on sweet corn field they’re planted on a 2 feet pitch and I can detect between the plants anytime and spud fields which are in furrows allowing me to stab it anywhere.mind you ,you could use 9inch round as well