PROGRESS REPORTS

The following is a chronology of events for the project including pictures of the windstorm damage.

CURRENT STATUS (6 Aug 97):

The antenna structure is completed. Elevation drive motor has been installed. Azimuth drive motor and drive chain, limit switches, positioning potentiometers and feed installation remain to be completed.

CURRENT STATUS (26 Nov 97):

Drive motors, drive chain, potentiometers and limit switches are installed and checked out. Feed supports and the cradle assembly to hold the feed are installed. I need a plastic garbage can the right size to cover the feed! Getting close now! More pictures coming soon.

CURRENT STATUS (26 Dec 97):

I have added more pictures showing my progress. The antenna is essentially finished. (Well, for now. These things are probably never REALLY finished!) All that remains outside is to install the coaxial cable. The feed shown is for 23 cm. I have a 21 cm feed roughed out, but I am thinking about some ideas for a variable polarization design before I complete it. I am now writing the software to control everything. So far I have the tracking program working on a 286 PC. I am using an A/D board to read potentiometers which simulate those on the actual dish and controlling small relays which will in turn control larger relays in the dish motor controller. After some finishing touches on the software and building the motor controllers and power supplies, I will finally be ready to listen!

CURRENT STATUS (1 Jan 98):

The software is working fine, and I can track sun, moon, satellites and celestial objects (in software). I am able to enter celestial coordinates in RA and DEC using two external 3-turn potentiometers which are read by the A/D board and displayed on the screen of the PC. Also displayed are the local coordinates of altitude and azimuth so I can immediately see where the antenna will go when it is switched into the automatic tracking mode. I also need to add the capability of entering celestial coordinates in galactic longitude and latitude. The motor controller is now finished and needs only a final test before connecting it to the antenna. I built two current-to-resistance transducers so that the PC can monitor the motor currents (amperes and degrees/second per ampere) while operating, just in case of overload.

CURRENT STATUS (14 Jan 98):

DISASTER! A freak windstorm moved through the area last night and damaged the antenna. Although the actual damage is not serious, it will require complete disassembly of the reflector. An iron casting in the mount broke under the wind load. The feed horn was ruined.

DISASTER!

1. The bottom of the elevation mount showing where the weld came loose.

2. The top of the rotating mast.

3. Overview of the mess.

4. The back of the dish showing damage to the screen and rings.

5. The feed horn and plastic cover.

CURRENT STATUS (15 Apr 98):

The antenna has been rebuilt! The mount has been strengthened so that the earlier problem cannot happen again. Never underestimate the force of the wind on a large parabolic antenna! The damage has caused me to waste 3 months in getting back to where I was on January 13; however, all appears to be working fine now. I am looking forward to receiving Hydrogen-line emissions soon! The feed assembly was rebuilt. The 1420 MHz feed horn has two ports consisting of 1/4 wave probes at 90-degree spacing. A 4-position relay is installed to allow switching between the two feed ports as well as to a hot load (ice water-cooled resistor) and a cold load (liquid nitrogen-cooled resistor). The load resistors are used for setting baselines for data collection as well as for quick check of system noise temperature.

CURRENT STATUS (3 May 98):

SUCCESS! Hydrogen-line emissions can be heard on the R-7000 receiver as an increase in background noise and seen on the Tektronix 2710 spectrum analyzer. I have written software to control the R-7000 for eventually taking data, but, for now I am encouraged by the results on the spectrum analyzer.

CURRENT STATUS (8 Dec 98):

I have modified the elevation sensor from a potentiometer operated by a hanging weight to a digital inclinometer. The potentiometer worked but was not precise enough. Its operation was slightly jerky due to friction. The digital inclinometer outputs a continuous ASCII text string showing its position which is read by a serial port on the 286 PC. Also, I have increased the counterweight from 300 pounds to 400 pounds, but I think I will eventually have to rebuild the counterweight system for better performance.

SPRING 1999:

Things continue to go well. I have obtained two YIG filters which will require power supplies for their heaters and tuning magnets. I will design the power supplies to provide +/- 5 volts so that they can also be used to improve the azimuth position accuracy (10-volt swing instead of only 0-5 volts).

SUMMER 1999:

The low noise preamplifier did not seem to be working. I replaced the PHEMT and now it seems to be fine. must have been due to some type of static discharge.

DECEMBER 1999:

Time to improve the web page to improve the look and include more details. I am getting a lot of e-mails lately requesting information. I have added the block diagrams and explanations. I have also included prices and possible sources of components.