Hollis Dinwiddie EVLA Front-End CDR – Feed Circle & Rx MountingApril 24, 2006

1

EVLA Front-End CDR

Feed Circle&

Receiver Mounting

Hollis Dinwiddie EVLA Front-End CDR – Feed Circle & Rx MountingApril 24, 2006

2

Flattened Feed Circle Layout

Hollis Dinwiddie EVLA Front-End CDR – Feed Circle & Rx MountingApril 24, 2006

3

Feed Circle Layout

Hollis Dinwiddie EVLA Front-End CDR – Feed Circle & Rx MountingApril 24, 2006

4

Vertex Cabin

Hollis Dinwiddie EVLA Front-End CDR – Feed Circle & Rx MountingApril 24, 2006

5

Vertex Cabin

• Each Feed is Tied into the Vertex Cabin Except the L-Band

• The Size and Receiver Weights Determine the Mounting Method for the Feeds and Receivers

Hollis Dinwiddie EVLA Front-End CDR – Feed Circle & Rx MountingApril 24, 2006

6

Receiver Weights

Receiver Weight (lbs)L 173S TBDC 84X 49

Ka TBDK 76

Ku TBDQ 79

Chuck Kutz 205

Receiver Weights

Hollis Dinwiddie EVLA Front-End CDR – Feed Circle & Rx MountingApril 24, 2006

7

Receiver Mounting

• Three Options for Receiver Mounting– Fully Fixed to Vertex Cabin– Fixed to Feed and Fixed to Vertex Cabin– Fixed only to Feed

Hollis Dinwiddie EVLA Front-End CDR – Feed Circle & Rx MountingApril 24, 2006

8

Receiver MountingQ and Ka

• The Receiver is Directly Mounted to the Feed Tower.

• The Feed Holds No Structural Load

• The Receiver is Attached to Side of Vertex Cabin

• No Major Stress Concentrations

Hollis Dinwiddie EVLA Front-End CDR – Feed Circle & Rx MountingApril 24, 2006

9

Receiver MountingK and Ku

• Feed Attached to the Feed Tower

• Receiver Attached to the Vertex Cabin Wall

• No Significant Stress in Feed

Hollis Dinwiddie EVLA Front-End CDR – Feed Circle & Rx MountingApril 24, 2006

10

Receiver Mounting

Hollis Dinwiddie EVLA Front-End CDR – Feed Circle & Rx MountingApril 24, 2006

11

Receiver MountingL S C X

• The Feed is Secured at the Mounting Flange and the Throat Section

• The Receiver is Attached Solely to the Feed

Hollis Dinwiddie EVLA Front-End CDR – Feed Circle & Rx MountingApril 24, 2006

12

Mounting the L-Band

Hollis Dinwiddie EVLA Front-End CDR – Feed Circle & Rx MountingApril 24, 2006

13

Keeping the Feeds DryRadome

• Sealing The Feeds– All Feeds or Feed Towers are Sealed with

Radome to Keep Moisture Out• Types of Radome

– Esscolam 10 for L, S & C– Gore RA7906 for X, Ku & K

Hollis Dinwiddie EVLA Front-End CDR – Feed Circle & Rx MountingApril 24, 2006

14

Keeping the Feeds DryDry Air Systems

• All Metal Feeds Sealed with O-Rings

• Desiccants • Dry Air Compressors

– Costly• Positive Pressure

Vertex Cabin– Experimental