[TowerTalk] Mixing a 20m yagi with a 40m yagi on the same boom.....

[Robert Thain]

Hello,
 
I have a question from my radio club,
 
We have a Hygain 4 element 20m monoband yagi (204) and a Cushcraft 40-2cd.
We would like to put them on the same boom. 
Something like a  EF-420/240 from force12.
 
Ideally we want to keep as much of the existing hardware as possible (Ie keep the hygain boom)
 
Have you done this (or similar)? Can it be done ? If so what changes need to made ?
 
Where should the 40m beam be placed on the '20m' boom. ie how should it be interlaced ?
 
Your input is greatly appreciated.
 
We do not have any body who is familiar with antenna software, I "think" it should be easier with that.  
 
Please reply direct and I'll summarise.
 
thanks Robert (g0hgw(at)yahoo.com) (at) = @