VLA/VHF Program Update 2005 October 31

Recent and Upcoming Events/Milestones

Jul 17   Complete field testing with prototype receivers and feeds at VLA. Begin
         Design and procurement for production units.

Aug 25   Second scientific peer review panel considers June 1 proposal for 
         observing time in the first trimester of 2007 (375 hours/source), to be 
         added to 85 hours already allocated in the 2005/2006 winter.

Sep  9   Panel recommends 250 hours for study of one    
         target, or 335 hours total.  450 hours were requested for estimates
         of likely sensitivity.  Impact assessment awaits measurement of      
         production receiver performance.

-Sep 26  Off site construction in Lincoln of full scale mockup of a VLA  
         subreflector.  The mockup enables measurements of feed (dipole) complex
         impedance for different lengths and separations from the existing NRAO 
         P-band feed and sub-reflector surface.

Sep 26-  Dipole and balun testing/optimization.  Improvement in the impedance 
         Match of feed, balun, and receiver over the prototype arrangement 
         should be substantial.

Oct 3    Preliminary approval of SAO funding for FY06, to be used for   
         completion of receiver construction and deployment.

         Shakedown of initial production receiver(s) uncovers fatal contractor     
         error in layout of the main circuit board and some minor design      
         inefficiencies.  Error eventually determined to be uncorrectable. 
         Deployment schedule suspended until new boards can be manufactured,
         stuffed and tested.

Oct 27   Revised board design delivered to contractor for layout work. 

Nov 7-19 Test measurements at VLA site of optimized feeds and baluns. Assessment 
         of relative gains for different separations from the P-band dipoles and
         subreflector.

Dec 1(?) Absolute system gain/temperature measurements of production receivers 
         coupled to the feeds.   

Dec 4-5  Next NRAO time allocation committee meeting.  Update on sensitivity due.


Socorro Travel

Nov 7 - 		Greenhill, Morales

Other Travel
Dec  4 - 11	Greenhill to Tasmania cosmology meeting

Notes 

Despite delay in manufacture of circuit cards, assembly of other elements 
Is complete, including weather tight enclosures, power supplies and control logic, and multi-wire power and control cables.  RF electronics (see Oct 3 entry) is the sole substantial activity.

Macos Diaz (BU graduate student in astronomy) continues work with the project at 
one day per week.  His present focus is finite element modeling for comparison 
with mockup test results. Lauren Peritz (Cornell engineering student) completed 
her work on balun electronics and returned to Cornell for her final semester on 
campus.  Idan Ginsburg continues his work in the group, executing assembly of 
basic hardware elements and testing.