JET PROPULSION LABORATORY                 INTEROFFICE MEMORANDUM

                                          TBHK 89-06

                                          April 13, 1989



TO:         N. A. Renzetti

FROM:       T. B. H. Kuiper

SUBJECT:    RADIO ASTRONOMY SIGNIFICANT EVENTS


The monthly radio astronomy meetings initiated last year by Gerry
Levy were resumed. Last week's meeting was devoted to plans for
new radio astronomy equipment. There was a consensus that, when
the K-band maser upgrades are completed, the Ground Based
Development task should be devoted to building one 43 GHz HEMT,
for use both at DSS-13 and on the 70-m antennas. This frequency is
of interest for VLBI, spectroscopy, and antenna evaluation. If the
70-m antennas prove to be useful at this frequency, additional 43
GHz receivers may be built later.

It was also agreed to continue to upgrade the general purpose,
IEEE-488 equipped instrumentation in the R&D cones. DSS-14 and
DSS-43 currently have IEEE-488 extenders between their R&D cones
and their radio astronomy areas.

A meeting was called by Roger Burt to discuss requirements for the
DSS-14 R&D cone in the 1-MW transmitter era. No specific
requirements could be provided for radio astronomy because the
scientific needs and technological opportunities are always
changing. However, there is a general requirement for maintaining
current capabilities for the foreseeable future, and for providing
adequate space for continued R&D activities.

Canberra Complex

Rex Quinn has returned from a Parkes task and met with Graham
Baines at the CDSCC on the way home.

Graham was informed that, because of lack of installed cables, the
controls for the 18-26 GHz maser magnet tuning will have to be
installed in the cone area. The radio astronomy development budget
cannot currently support the high cost of installing these cables.
Other controls, such as BWO and LO tuning, will be remotely
operable via the IEEE-488 link.

Rex and Graham further discussed a parts list, to discover any
possible missing pieces not returned to JPL, in anticipation of
re-assembling all pieces later this calendar year.

Goldstone Complex

The phase-lock loop of the 18-26 GHz receiver has been fixed. The
circuit will now be adapted to operate with the YIG-tuned Gunn
oscillator borrowed from the Canberra 18-26 GHz receiver.
Meanwhile, an interim continuum observing capability using an
IEEE-488 controlled power meter continues to be pursued.

No further 32 GHz observations were made during the previous week
because the Dicke switch failed. The unit is at JPL for repair.

Madrid Complex

Cooldown of the 22 GHz Maser for MDSCC will start on 12 April in
the JPL Cryogenic Lab. This step is necessary prior to roof tests
to verify performance because of the lapse of time since the maser
was last operated.