RxW

Receiver RxW will be ready for general use in Semester 99A. It is a dual channel receiver that operates roughly between 430 - 510 GHz (C-band) and 630 - 710 GHz (D-band). The actual tuning range might be slightly different. Updated information about the tuning range and other parameters will be published on the web when available.

RxW was built by MRAO with the D-band mixers supplied by SRON. The receiver actually has four mixers - 2 at C-band and 2 at D-band. However, the optics only allows one pair of mixers to be used at any given time. Further the LO system only supports use at one frequency at any give time. Thus the receiver is a dual channel C-band or D-band receiver with no mixed mode available. The receiver is normally operated in Single SideBand (SSB) mode with the unwanted sideband terminated on a cold load. However, Dual SideBand (DSB) operation is possible. The tuning is partly automatic. The LO chain still needs to be tuned manually by the TSS while mixers and diplexers are tuned remotely. Switching between C- and D- band also is manual.

As might be apparent from the above the commissioning of the receiver is not finished. The receiver arrived in Hawaii early June this year. However, the commissioning has been delayed by several problems. First and most severely by a failure of the compressor which operates the receiver's closed cycle cooler. Further there has been problems with the optical alignment, electronics and software. The most severe remaining problem is a wiring fault inside the dewar affecting a HEMT used for the D-band. Thus only one D-band channel is currently operating.

We are confident that all remaining problems will be solved before the start of the Semester 99A. The receiver will also be available for general use during the fall (latter half of Semester 98B) on a best effort basis. However, we do anticipate at least two periods when the receiver will be warm and not available. It should also be noted that until the end of the commissioning not all receiver parameters will be known and users need to measure efficiencies as well as check calibration carefully. Whenever new or revised information is available it will be placed on the web.

Current performance

Efficiency:

The beam efficiency measured on Jupiter is about 0.5 at C-band and 0.3 at D-band.

Beam size:

Not yet available.

Pointing:

The current relative pointing offset between the two channels at C-band is:

channel (B - A) Az: -0.9"+/-0.2" El: 1.0"+/-0.2"

The relative pointing between the channels at D-band has not been measured after the last alignment. However from earlier data the relative pointing offset is believed to be close to the C-band values.

Noise temperatures (SSB):

Frequency  Sideband  A-channel   B-channel   Line

 (GHz)                Trx (K)     Trx(K)         


 430.00      LSB       420         290           

 461.04      USB       300         300    CO 4-3 
     
 461.04      LSB       330         340           

 492.16      USB       340         340    CI     

 508.53      USB       330         490           


 
 630.00      LSB      ----        3000           

 636.53      USB      1400        1700           

 661.07      USB      1100        1100   13CO 6-5

 691.47      USB      1100        1100     CO 6-5