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(antennas destroyed by winter storms)
After eight years of intermittent operation, The SETI League's 1296 MHz EME Beacon suffered catastrophic antenna failure in March 2009, due to high winds. It is unclear at this time whether a repair will be attempted, the eight 55-element loop yagis will be replaced, or another antenna design will be attempted. Watch this space in the weeks ahead for further details.
The SETI League Moonbounce Beacon, first activated at low power on 4 March 2001, has experienced intermittent outages since 23 July 2001 for rebuilding, and the addition of a solid-state high-power amplifier. On Sunday, 17 February 2002, the W2ETI beacon began operating experimentally at nominally 200 Watts of output (100 Watts at the antenna), key-down during the first full minute of every five-minute clock interval.
After a ten week outage for maintenance, the W2ETI 1296 MHz EME Beacon was again returned to service at the 200 watt level on 22 October 2002. The solid state power amplifier's reliability and stability remained a problem, and several unscheduled outages followed.
The beacon remained operational at full power throughout the two weekends of the 2002 ARRL EME competition, and was copied by at least two stations. The power amplifier then began operating at slightly reduced power, until suffering a power failure on the morning of 12 March 2003. This resulted in a one-month outage, which provided us with the opportunity for much-needed system refurbishment. The beacon was returned to service at the 100-Watt level on 13 April 2003, just in time for planned tests with the Arecibo and Jodrell Bank Radio Observatories.
Subsequent outages for power module replacement occured on several occasions, with output power levels generally ranging between 100 and 150 watts. Power amplifier reliability remained a problem. The beacon power amplifier used sixteen Mitsubishi M57762 RF modules in its final stage. These modules proved quite unreliable, especially when used continuously twelve hours per day. Having replaced several such modules over the period of a year (at a cost of roughly $100 US apiece), we began studying alternatives to this particular solid state power amplifier.
Following a power supply failure on 6 November 2003, the W2ETI Moonbounce Beacon underwent an emergency repair, and was returned to service just in time for the November 15-16 ARRL EME Contest period. It remained operational until thunderstorms in the Spring of 2004 inflicted lightning damage. The beacon was taken off the air in mid May, 2004, to replace a stuck relay, and to evaluate the feasibility of rebuilding the power amplifier with more robust devices. The EME beacon remained offline for nearly two years, awaiting extensive repairs to the badly damaged PA.
The beacon was returned to service in March, 2006, after nearly a two-year outage. The completely refurbished beacon gained a new half-kilowatt MOSFET linear power amplifier, the MKU 13500 A, obtained from Kunhe Electronics in Germany. During this extended maintenance period, the beacon also gained a repackaged exciter, atomic and GPS frequency standards, new control computers and associated software, new power supplies, and a 3 kW UPS. This latest iteration of the beacon is depicted on the personal website of station trustee Richard Factor, WA2IKL
The beacon was taken offline on 27 February 2007, for re-cabling and installation of new antennas. An array of eight 55-element loop yagis from Directive Systems was installed in June 2007, and underwent a period of testing, alignment, and aiming. The intent of the new antenna array was to increase the beacon's Effective Isotropic Radiated Power (EIRP) to a level which will permit reception by the typical Project Argus radio telescope. Unfortunately, the alignment of the yagis was compromised by high winds just weeks after installation. Two years later, while still undergoing repairs, the yagis were completely destroyed by severe winter storms.
The EME beacon remains a work in progress. Even after it is eventually returned to service, there may continue to be unannounced outages while we work to improve its antennas, and also as we work toward doing test transmissions in JT-65 digital mode. Watch this page for status updates, and thanks for your patience.
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this page last updated 14 March 2009
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