Preparing the feed assembly
If the feed horn 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 feed horn is, you will
have received by default the
C13F
collar. It is best if you have discussed with your sales
rep the feed horn you are using prior to shipping so that
DH Satellite
can make sure you
have the proper collar to mate to your feed horn. You do need to make sure your feed
horn and collar are the correct combination.
Take the scalar ring of the feed horn 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 (see fig.
#6). Tighten all nuts& bolts. Figure #7 is the final assembly for the Ku band showing a
Ku straight thru 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”
Fig. #6
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