St40 and p79 in hull transducer

Hi I have a st40 depth display that I installed with an in hull p79 transducer and it has been acting up since the beginning. I read some where that the ST40 was not recommended for the p79 transducer because it was not powerful enough. Would a st60 display or Isereies display work better and could these units talk to another ST40 slave.

Thanks

Duane