Tribander prox. to monobander; small tribander stack

[tonyjw@primenet.com (Tony Wanschura)]

It's time again to into tap the know-how resident this reflector. 

First, what vertical separation would you recommend between a 20 
meter monobander and a 10/15/20m tribander on the same tower.  The 
two antennas will not be fed together.

Second, I'm curious about stacking distances for small tribanders.  
There is supposedly an article on this subject in the latest NCJ (I 
let my subscription run out).  Can someone summarize the conclusions 
of this article for me?

Thanks,

Tony  KM0O  
kayMOO, one of the Minnesota Bovine Contest Club (the other member 
is AC0W)