DFM Engineering, Inc.
1035 Delaware Ave. Unit D
Longmont, CO 80501
Phone: 303-678-8143
Fax: 303-772-9411

PARI - Pisgah Astronomical Research Institute
Control System Upgrade
26-meter (85-ft) antennas

DFM Engineering, Inc. completed upgrading the first of two 26-meter (85-ft) antennas at PARI (Pisgah Astronomical Research Institute) located in a picturesque valley of the Appalachian mountains near the south western tip of North Carolina.

The antennas were originally used for communications with the Apollo Space capsule and later were used to track and communicate with various other artificial satellites.

The Institute is converting the site to perform radio and optical astronomy.

The original (1962) variable speed drives for the antennas consisted of a large constant speed AC motor driving a computer controlled variable displacement hydraulic pump. The major axis motor was 150 horsepower while the minor axis was 75 horsepower. The variable flow rate of high pressure oil was used to drive two constant displacement hydraulic motors per axis that drove the antenna through large gear boxes. The antennas could track at rates up to a few degrees per second, but could not track slowly enough to track stellar objects.

DFM Engineering, Inc. was contracted to replace the drive system with modern AC servo motors capable of smoothly operating over a wide velocity range sufficient to allow tracking of stellar objects and artificial satellites.

The new servo motors have a continuous power rating of 11 KW (about 15 horse power) each. These motors can operate over the full velocity range needed and are far more efficient than the hydraulic system.

The old system required about 200 kilowatts of power. The new system, while tracking, consumes about 10 kilowatts. The cost savings in power alone could amount to tens of thousands of dollars per year per antenna.

The Antenna Control System is very similar to the DFM Engineering standard Telescope Control System (TCS). A PC type computer is used to generate the motor commands, check for limits, provide an operator interface, and provide an interface to the observatory control computers. This system also adds a "Repeater" in the control room which is approximately 2000 ft. from the first antenna.

Presently, DFM Engineering is completing the hardware for the second 26-meter antenna. The installation will begin in late June so that the second antenna can be operational by mid July. This scheduling will allow Dr. Cline to achieve his goal of transforming the Institute into an educational facility.

Don Cline, at PARI has been instrumental in transforming the Institute that will eventually host visiting astronomers, about 30 undergraduate physics departments and offer access to facilities to many nearby primary and secondary schools.