For some reason when fisher brought out the x series there were that many new models being pushed out they were more powerful than their predessor a retired fisher engineer in America said it was a ploy to sell the newer model
If two of the circuit resistors are changed they all have substantial depth gains this old beast has been done and depth is not a problem on the beach most of my finds here are upto a foot no where near a pi but up for filey with its sand then clay but far deeper than stepsons ace 250 he regrets selling his fisher 1236x2 on this forums auction

Thought we had found your bling stash today I'm sure we are homing in on it
