Stacked TH7's

[Dave_Raymond-CSUS04@email.mot.com (Dave Raymond-CSUS04)]

     I'm in the process of getting ready to build up a rotating Rohn 55 
     130' tower.  I have the guy rings and the rotating base already built 
     up.  I'm planning on guying the tower with a stationary set of guys at 
     40', then guying it with guy rings at 80' and 120'.  
     
     I was planning on putting 3 TH7's up at 42', 82, and 122' (it's 
     convenient to mount one above each set of guys-also, there will be 
     ultimately be other HF antennas on the tower).  However, after 
     reading the TH7 stacking info in the recent NCJ, I'm not so sure 40' 
     spacing is the way to go.  
     
     I've not gotten into using the various modeling software (yet).  
     Anybody out there tell me what the front to back ratios look with this 
     spacing?  Are they really poor?  How about 30' spacing?  I could go 
     either way.
     
     Any comments, ideas, or recommendations??
     
     73....Dave Raymond/WA0FLS