NEWINGTON, CT, May 8, 2001--The inaugural AO-40 transponder tests have been a huge success. Reports from amateurs making their first contacts on AO-40 have come from all over, and more surely will follow over the next week as the experimental operation continues.
"It was just great!" enthused AMSAT-NA President Robin Haighton, VE3FRH, who worked a dozen or so stations via AO-40 over the weekend, including contacts with other Canadian stations as well as with Alaska, Virginia and Arizona. "Once we get it pointing directly at us, we'll be laughing," he said of the spacecraft. "It will be very strong and very effective."
AO-40 ground controllers opened up the next-generation satellite's transponders May 5 for general amateur use on an experimental basis. Stations can uplink on either 435 MHz or 1.2 GHz. The transponder downlink is at 2.4 GHz. The operation is experimental, the schedule subject to change, and the transponders could be shut down at any time without warning.
Mike Seguin, N1JEZ, in Vermont, was first to report his contacts on the AMSAT bulletin board. "I've successfully logged a dozen contacts in the first hour of operation, including two contacts using the Mode-L uplink," he said. "I also logged my first DX contact with IZ8EDE." Seguin said his final tally was 24 contacts. "A great first day! Let's hope for many more."
Ed Krome, K9EK, in Indiana, echoed N1JEZ's comments. "Wow, AO-40 was terrific on this first morning of transponder operation, he said. "After almost 10 years, what a thrill!
 The AO-40 antennas at KK5DO in Houston, Texas. [KK5DO Photo] |
Bruce Paige, KK5DO, in Texas also got lucky, racking up several European DX contacts, including G6VLB, G3WDG, and F6CBQ. "I heard the beacon about S8, S9," Paige said. "The SSB QSOs were S5-S7. They sounded really good."
Seguin said the comment he heard most often was how weak the S-band downlink was for some stations. "In these situations, the natural tendency is to increase uplink power," he said. AO-40 was operating without the benefit of the LEILA system, which can compensate for stations that are too strong in the uplink. Seguin suggested that it was just a matter of getting used to the satellite at this point.
At this point, AO-40 may be available for use several hours a day, starting at MA 136 and continuing through MA 240, as the spacecraft heads closer to Earth. During the weekend passes, the transponders were available for six hours or so from a given point on Earth.
The tests have shown that uplink frequencies (without taking Doppler into account) are 435.495-435.780 MHz and 1269.211-1269.496 MHz, and the downlink passband is 2401.210-2401.495 MHz. The transponders are inverting, so a downward change in uplink frequency will result in an upward frequency shift in the downlink.
The AO-40 beacon, as monitored in Connecticut. [00:33] |
Users are being asked to avoid the "middle" telemetry beacon at 2401.323 MHz and give it a clearance of 5 kHz on either side. Stations should keep clear of 435.645-435.685 MHz and 1269.360-1269.400 MHz. For maximum QSO signal strength, stations should aim for a passband signal that's 10 dB below that of the middle beacon.
AMSAT-DL (Germany) reported reception reports "with good signals" from stations using dishes as small as 35 cm in diameter or 16-turn helix antennas and running as little as 25 W on UHF or 100 W on 1.2 GHz.
Some of the activity over the weekend on AO-40, as monitored by Maggie Leber, K3XS, in Pennsylvania. [00:56] |
"During the whole operation temperatures kept normal and the power budget was positive with an sun angle of about 4 degrees," AMSAT-DL said of the first day of AO-40 transponder operation.
Haighton expressed appreciation for the "very hard work" of Project Leader Karl Meinzer, DJ4ZC, AMSAT-DL President Peter Guelzow, DB2OS, and the worldwide support group of command stations and technical advisors "for providing us with a great satellite."
"To satellite enthusiasts there is nothing quite as exciting as working a new bird, especially when we have all watched and waited as AO-40 went through its troubles and (now) is returning to us as a great satellite," Haighton said in a statement to AMSAT News Service.
Following the transponder experiment, ground controllers plan to raise AO-40's perigee by approximately 200 km.--thanks to AMSAT News Service
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