Preparing the Feed Assembly
If the feedhorn you have selected has an adjustable scalar ring, move it to the proper wave-guide setting.
The
2.4M, 2.7M, and 3M antennas all have the same f/l. The F/D ratio is listed below for each. Be
sure to measure from the center of the dish to the throat of the feedhorn when using a Chaparral
style feed. You should be measuring 35 ¾” from the center of the dish to the throat of the feedhorn
for C band. Ku band is more critical so please if using a C/Ku band feedhorn to error on setting it up
for measuring the Ku which would be 35 7/8” from the center of the dish to the throat of the
feedhorn.
Major adjustments for Ku band can be made by placing the three-piece collar on
either side of the horseshoe collar.
Special note: Seavey feeds are measured to the scalar ring and not the throat.
Unless you have specified what brand name and frequency your feedhorn is, you will have received by
default the
C14F
collar. It is best if you have discussed with your sales rep the feedhorn you are using prior
to shipping so that
DH Satellite
can make sure you have the proper collar to mate to your feedhorn. You do
need to make sure your feedhorn and collar are the correct combination.
Take the scalar ring of the feedhorn and place it under the collar with rings pointing toward the dish. Turn
it until all three holes line up between the two and insert the ¼” x ¾” bolts through the scalar ring and then
through the collar; fasten with the ¼” nuts. Most
C-
band and dual feeds have a 3-bolt pattern on the scalar
ring just for this. Tighten all nuts and bolts. Figure #7 is the final assembly for the Ku band showing a Ku
straight through feedhorn being used.
Check to see that the feed is at the focal length, the actual focal length should be ¼”
inside the wave-guide, for C-band and 1/8” for Ku band.
8' 35 ¾” Focal Length - .375 F/D - Wave Guide 9/16”
9’
35 ¾”
Focal Length - .33 F/D -Wave Guide 5/8”
10’
35 ¾” Focal Length - .3 F/D -Wave Guide 7/8”
KU4FL
FIG. #6
PAGE 10
FIG #7
C14F COLLAR AND STRUTS
Strut Local on Ring Face of 4PC Sectional
Antenna 8 Block Ring
