[asac] [almanews] ALMA Memos 341 and 342 Released

[Carolyn White]

ALMA Memo #341

Selection of HFET or SIS Mixer for ALMA Band 3

J. C. Webber
January 3, 2001

The selection of an HFET amplifier or SIS mixer for ALMA Band 3
(nominally 89-116 GHz, with the option of extending the low end 
to 85 GHz) has been debated for several years. In this memo, I 
attempt to set forth the criteria on which the choice should be 
based and provide some of the information needed to make the 
final decision.

View a PDF version of ALMA Memo #341 at
http://www.alma.nrao.edu/memos/html-memos/alma341/memo341.pdf

Download a postscript version of ALMA Memo #341 from
http://www.alma.nrao.edu/memos/html-memos/alma341/memo341.ps

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ALMA Memo #342

An Improved FX Correlator

J. Bunton
December 19, 2000

The advantage of FX correlators increases as the number of 
antennas increase making it well suited to ALMA. Initial 
correlator designs use the XF topology to avoid the cabling 
problems with traditional FX correlators. This memo shows how 
the cabling problem can be eliminated and demonstrates an 
implementation using of the shelf technology. Initial estimates 
show that this design could be an order of magnitude cheaper to 
implement than a custom chip XF design.

View a PDF version of ALMA Memo #342 at
http://www.alma.nrao.edu/memos/html-memos/alma342/memo342.pdf

Download a postscript version of ALMA Memo #342 from
http://www.alma.nrao.edu/memos/html-memos/alma342/memo342.ps
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