[Moon-Net] 2.4M PRIME FOCUS / 2.4M OFFSET/ ALSO SEPTUM FOR 1296

TexasRF at aol.com TexasRF at aol.com
Mon Nov 21 23:22:13 CET 2016


Serge, the offset dish will have better efficiency because of less feed  
blockage and better illumination. The offset dish has a higher focal length 
and  the preferred feed is one of the dual mode/W2IMU designs that is tailored 
for  your particular f/d. One size is not optimum for all f/d. I may be 
wrong, but  know of no commercial sources for these feeds so you will have to 
build your own  feed.
 
Use of a septum polarizer is a separate issue so you can "borrow" an  
existing septum design for that part of the project.
 
If you are not up to building and tuning a high f/d feed, you may well  
prefer to go with a prime focus reflector as most of the rest of us have  done.
 
There are Canadian sources for 10 ft prime focus dishes on Ebay if you  
decide to go that way. They are made for C and Ku band TV and aluminum  
construction. They typically are made with four segments to make assembly easier  
and lower shipping cost. 
 
Some of them come with a linear actuator polar type positioner that can be  
modified for elevation control.
 
73,
Gerald K5GW
 
 
 
In a message dated 11/21/2016 3:01:12 P.M. Central Standard Time,  
ve1kg at eastlink.ca writes:

Which is best a 2.4M prime focus dish or a 2.4M  offset dish? & WHY? What 
kind of septum would you use on both dishes for  1296???
Thank you 
Serge,  VE1KG


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