[Antennaware] G5RV balun question

[John]

I have a G5RV type antenna I homebrewed. It is around 100 feet long,
fed in the center with around 25 feet Radio Shack twin lead (300ohm).
At the end of the twin lead is currently a HI-Q brand 4:1 voltage
balun, and then a run of 75ohm coax to the shack.  I want to replace
the balun with something that will keep RF off of the coax shield-I
understand I need a current balun for this.  What are the best brands
and models to use for this?

73 John AF5CC