GBT Gregorian Receiver Status

F.J. Lockman and R. Norrod

September 3, 1992

The attached table summarizes the current status of the Gregorian
receiver system described initially in GBT memo No.66.  The second
column gives the nominal frequency coverage of each receiver.  All
will perform well up to their band edge.  The "Wide IF" will
block-convert the entire front-end bandwidth to the 1-8 GHz range.
NRAO will provide converters tunable over this range with 10 KHz
resolution, allowing users to observe widely separated spectral lines
simultaneously, for example.  The lower-frequency receivers will use
an IF system with a bandwidth of about 500 MHz.  Column 5 identifies
receivers that would be used with a tertiary reflector (to be
designed) for pointing or beam-switching.  Column 6 shows whether we
plan to build initially one or two feeds for a given receiver.  The
feeds would be separated by 5 to 7 HPBW's on the sky.  Note that each
feed of a receiver will detect both polarizations, so "dual feed"
implies that there will be two feeds, four RF amplifiers and four IF
lines.  A general priority ranking of the receivers is given in column
7.  Those of rank 1 and 2 will be completed by the time the GBT comes
online in early 1995, with the others to follow as soon as possible.


September 3, 1992


                      GBT GREGORIAN RECEIVERS


Receiver   Freq.       BW     Wide IF   Tertiary  Dual Feed   Rank   Status (completion date)
           (GHz)      (GHz)

   1     1.15-1.73    0.58       No       No         No        1    Under development (Sept. 1993)

   2     1.73-2.60    0.87       No       No         No        4    

   3     2.60-3.95    1.35       No       No         No        3    

   4     3.95-5.85    1.9        No       No         No        2    Under development (Nov. 1993)

   5     5.85-8.20    2.35       No       No         No        3    

   6     8.00-10.0    2.0        Yes      No         No        2    Ordering parts (Sept. 1993)

   7     10.0-12.4    2.4        Yes      No         No        3    

   8     12.0-15.4    3.4        Yes       ?         Yes       1    Ordering Parts (May 1993)
   
   9     15.4-18.0    4.6        Yes       ?         No        4

  10     18.0-22.0    4.0        Yes     Yes        Yes        2    Under Construction (Dec. 1992)

  11     22.0-26.5    4.5        Yes     Yes        Yes        1    Under Construction (Dec. 1992)

  12     26.5-33.0    6.5        Yes     Yes        Yes        3    (1994?)

  13     33.0-40.0    7.0        Yes     Yes        Yes        3    

  14     40.0-45.5    5.5        Yes     Yes        Yes        1    (1994)

  15     45.5-52.0    6.5        Yes     Yes        Yes        2    (1994)