Topband: active antenna height

[Gary Smith]

I've decided to make the plunge and buy one of the 8 element active 
arrays for 160M-40M. Looking at the price for the antenna kit, it's 
just too much considering the cost of the electronics, so I need to 
roll my own.

I was thinking of getting the Telescoping Aluminum Tubing that comes 
in 6' lengths from Texas Towers; .375", 5" & 6.25". If I slide each 
inside 6", that'll come to a 17' tall element. Is that sufficient 
height? Would adding another 2-3 feet make any difference with these 
kind of active antennas?

73,

Gary
KA1J