I know this has been kicked around some.---I'm thinking of trying the F75 DD coil on my F70.--Is this a good plan?---The areas I usually hunt in are quite mineralized and most of my hunt sites are fairly trashy.---It should help me with target seperation---will it mess me up with steel bottle caps (much more than the F70 concentric)?----What would other advantages & disadvantages be? I'm trying to locate & purchase a F75 DD coil--anybody know where I can find one?--Fisher has them on back order as accessory coils right now.---------Thanks, Del