40' DISH EXTENSION PROJECT

(Updated: November 28, 2009)

The objective of this construction project is to increase the aperture of the existing 340" (8.6 meters) diameter Kennedy dish to 480" (12.1 meters) diameter by constructing additional steel support structures and six additional aluminum petals to form a large annulus around the existing dish. The new annulus will double the receiving area of the dish resulting in a 3 dB increase in both transmit gain and receive gain relative to the original 340" diameter dish. Extending the aperture of the dish will change the f/D ratio from 0.43 to 0.30. Previous measurements by K5SO on the dish using the VE4MA-style feed with scalar ring show that the feed will be able to properly illuminate the extended dish by repositioning the scalar ring to a new position that is about 1" further from the reflecting surface of the dish than the previous scalar position.

EXTENSION DESIGN DIAGRAMS

CONSTRUCTION PROGRESS

Photo above: Four of the six new steel support members (painted black) are in place under the 340" diameter dish to receive the new steel hexagon structure. Initial scaffolding assembly and leveling is underway in this photo. (Oct 16, 2009)

Photo above: K5SO checking the new steel hexagon structure for correct bolt plate fit before attaching the members to the new steel support arms on the dish. (Oct 16, 2009)

Photo above: Twenty-foot high temporary scaffold assembly is nearly complete in this photo. The final top plank is resting on next lower level, awaiting installation on top. Scaffold sections are tied together and also tied to the existing feedhorn maintenance stand for safety and added stability. (Oct 16, 2009)

Photo above: K5SO with steel hexagon structural beams and side support beams prior to installation. (Oct 18, 2009)

 

Photo above: K5SO installing a steel side support beam for the new hexagon structure. (Oct 18, 2009)

Photo above: K5SO installing a steel hexagon side beam with Tom K4KIY observing. (Oct 18, 2009)

Photo above: Steel hexagon beams mounted onto dish with vertices of the hexagon nominally positioned beneath the rim of the dish; awaiting final minor vertices position adjustments. (Oct 18, 2009)

Photo above: Steel hexagon support structure is installed and properly positioned, awaiting fabrication and installation of the aluminum extension petals. (Oct 20, 2009)

Photo above: Rolling inner rim of the first petal extension to match the curve of the outer rim of the 8.6m dish. Rim material is 1-1/2" x 1-1/2"x 1/8" wall square aluminum tubing. Pipe wrench is used to keep the tubing aligned properly in the tubing roller. Multiple passes through the roller are necessary, increasing the bend slightly each time. (Nov 24, 2009)

Photo above: Rolling of the three main concentric support arms for the first of six extension petals is complete. Left to right are: the outer rim of the extension petal, middle arc support, and inner rim of the extension panel that mates to the outer rim of the 28' dish. (Nov. 28, 2009)

 

More photos will be added as additional progress is made.

 

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