AGO2 Station Report
2000-2001 Summer
UT Day 352 - 358





On-site personnel:

Kevin Killilea, Thai Verzone (Field personnel/Groomer), Tom Barfield and Todd B. Johnson (AGO engineers) comprised the service crew for the AGO-2 2000 season.

Station:

The station was cold upon arrival and the emergency shut-off valve had activated. There was no ice on the exhaust shroud, however a 1-inch plug of ice had formed inside the air filter. This restriction of airflow is not a probable cause for station failure since there are several ways air can enter the shelter. There was no propane left in the system, and on one of the tanks there was a substance residue with an odor of ethyl mercaptan indicative of a leak. It is believed that the station ran out of fuel on or about Julian Date 172, the 21st of June.  The technical service team switched the fuel supply to the auxiliary tank and easily started TEG. After the TEG was engaged, the station temperature rose to 20-25 C. This temperature was maintained throughout the service call. The bottom of AGO-2 was approximately 2 feet below grade. This is about the same height as last year. The bowl around the station seems to be in equilibrium and it was decided that the station did not need to be raised this year.

TEG:

The TEG was rebuilt and burner temperatures were maximized. The TEG Turbo was modified to allow it to extract power directly from the PSC. The turbo source now has the highest priority for power use at the AGO station. Experiment # 13 was not functioning properly so the Turbo was connected to experiment # 12 for its power. New batteries for the turbo were installed. Batteries for the electronic shutoff valve were also replaced. The manifold propane pressure is set at 3.0 psi. The maximum burner temperatures that could be reached were in a range from 200 ? 250 C. These temperatures, while lower than expected, yielded a sufficient voltage and current to drive the station electronics. Freon pressure is 20 psi.

The maximum burner temperatures that could be achieved were:

#1 210 C

#2 235 C
#3 245 C
#4 245 C
#5 240 C
#6 245 C
Aluminum baffle plates were installed above the vertical air fins to restrict air movement through the internal TEG heat exchanger.
Data Control Unit (DCU):
Two Storage computers (Rev 2, SN: 00-009 and 00-010) were installed in the DCU. The old storage computers were removed and will be shipped to Augsburg College for data retrieval and processing.
Power Supply Controller (PSC):

The PSC was operating when the team arrived at the station. The PSC was operating normally and all channels, with the exception of channel 13, were checked and worked effectively. Power was being delivered to all experiments. The BAGOEXP board was updated with PIC TIPIC002 rev. 04. See AGO2.AGO for experiment power settings, priorities, and other station information.

Data Acquisition Unit (DAU):

All functions were normal. New non-volatile random access memory was installed in the DAU and the software was upgraded to Rev. 3. See AGO1.AGO for DAU settings.

Global Positioning System Receiver (GPS):

The GPS was functional when the AGO electronics were turned on.

Bell Labs Fluxgate Magnetometer:

Data was examined to verify the operation of the experiment. From the data it was determined that the site was at a geomagnetic null. The magnetic variometer indicated a 20% positive position off center, when on the D axis. The service team determined that there was a need to realign the sensor level and to zero the D axis. This was done on day 356 and the box containing the sensor remained in its original position. The cover for the vault was raised to the surface and marked with flags. Data for the experiment was collected prior to the leveling of the magnetometer.  See images A2_CH03.gif, A2_CH04.gif, and A2_CH05.gif.

Current settings for the magnetometer are:

Sensitivity : 1000 nT

H Offset : + 00 01 968
D Offset : OFF 00 00 000
Z Offset : - 02 02 850
The electronics were checked per the servicing documentation. There was no fault found in the H axis bias selector switch and all wire harnesses were in the correct position. The magnetometer was leveled and the D axis was zeroed. The data collected was as follows:
Axis Meter Out DAU
Reading Reading
H: -10.000 V 0002 Hex.
+ 0.000 V 0800 Hex.
+10.000 V 0FF8 Hex.
D: -10.000 V 0055 Hex.
+ 0.000 V 0800 Hex.
+10.000 V 0F8C Hex.
Z: -10.000 V 0001 Hex.
+ 0.000 V 0800 Hex.
+10.000 V 0FF8 Hex.
Tohuku ULF Search Coil:
The search coil experiment data showed no variance in relation to data collected the previous year. The receiver data rate was changed to 0.1s. Data was collected from the experiment and stored on the service computer. See images A2_CH06.gif, A2_CH07.gif, and A2_CH08.gif.
Stanford VLF Receiver:
The Broad Band experiment boards were installed in the system. Boards containing R12 and R13 were examined. One board contained a set of 10k ohm resistors and one board did not. R12 and R13 on the second board were replaced with 10k ohm to account for the new antenna load. All boards now have the required 10k ohm configuration. The battery/power system was modified and the batteries were removed. A larger version of the E/W antenna was installed which modified the existing antenna. Data was collected and examined for possible problems in the system. Dummy loads were not available so the calibration was conducted with the antenna both attached and disconnected from the system. Data was collected from the experiment and stored on the service computer. See images A2_CH09.gif, A2_CH10.gif, and A2_CH11.gif.

Settings for the experiment are as follows:

8 ? 16 kHz 20 dB

16 ? 32 kHz 20 dB
0.5 kHz 20 dB
4 ? 8 kHz 20 dB
24.0 kHz RF 20 dB
IF 15 dB
1 ? 2 kHz 10 dB
2 ? 4 kHz 10 dB
30 ? 40 kHz 10 dB
1 ? 2 kHz 10 dB (E/W)
Line Receiver N/S 30 dB
Line Receiver E/W 35 dB
VLF Receiver Calibration Table:
Channel Band (kHz) Freq. (kHz) w/Antenna (VRMS) w/o Antenna (VRMS)
9 0.5 ? 1 0.75 3.48 2.21
10 1 ? 2 1.5 1.68 1.59
11 2 ? 4 3 5.06 4.70
12 4 ? 8 6 8.47 8.35
13 8 ? 16 12 8.97 8.96
14 16 ? 32 24 9.11 8.94
15 30 ? 40 35 8.61 8.75
19 1 ? 2 1.5 6.02 2.04
20 24.0 24 8.17 8.02
University of Maryland Riometer:
The experiment was observed for a 24-hour period and data collected on the service computer indicated normal activity. There was no indication of data clipping at a lower than expected values.
Dartmouth LF/HF Receiver:
Dartmouth was upgraded for a sample rate of 40 samples per second. Data was collected, examined and stored on the service computer.

Allsky camera:

The Allsky camera upgrade was completed using a spare camera control board and by removing one A/D converter from the processor board. The serial connection was established through the ground support equipment connector on the front panel and data was verified through the service computer. A copy of the image seen from the camera image program was stored on the laptop.

Anubus Seismic:

The experiment could not be completely serviced. The Epson handheld terminal was dead on arrival at AGO-2. The equipment had been checked out prior to arrival in the field and the switch was off when the case was opened in the field. The batteries were dead and attempts were made to charge the system, however the unit would not turn on. Accordingly the equipment was left operational and as-is. Data was collected from the experiment and stored on the service computer.  See images A2_CH96.gif.
 

Miscellaneous:

GPS position: S 85 40' W 46 24'. Elevation: 6100 ft.

Notes for the future:

1) Whenever a power source or experiment has been modified, it should be tested for greater than 1 MOhm isolation to chassis BEFORE the unit is connected to the PSC. The PSC is very sensitive to violations of this specification.