The amateur radio satellite AMSAT-OSCAR 7 was launched by a Delta rocket from Vandenberg Air Force Base on November 15, 1974 and provided many years of service until it went silent from battery failure in mid 1981.
For 21 years nothing more was heard until June 21, 2002 when Pat Gowen G3IOR came across a beacon sending slow 8 -10 wpm CW on 145.973.8 MHz. It sounded like old OSCAR satellite telemetry, it had the familiar HI HI followed by a string of numbers in groups of three. After monitoring by many radio amateurs it turned out to be OSCAR-7, and it seemed to have come back from the dead.
Pat’s email to the AMSAT Bulletin Board announcing his discovery can be seen at
It is believed that in 1981 the batteries failed short-circuit, however, in 2002 they became open-circuit enabling the satellite to run again from the solar panels. Since that day OSCAR 7 has been operational when in sunlight and provided radio amateurs with many long distance (DX) SSB/CW contacts.
Remember when working OSCAR 7 use the least uplink power possible to minimize your downlink power usage, and maximize the number of simultaneous contacts supported in the passband.
A BBC News report Radio ham finds lost satellite about the reception of OSCAR 7 by Dave Rowan G4CUO can be seen at http://news.bbc.co.uk/1/hi/england/2149381.stm
A collection of photos by Dick Daniels W4PUJ taken during the construction, test and launch of the AMSAT-OSCAR 7 spacecraft in 1973 and 1974 can be viewed at http://n4hy.smugmug.com/AMSAT/AMSAT-Oscar-7
Details of the June 1981 battery failure and a list of AO-7’s achievements can be found on pages 37-40 of the 1981 AMSAT Satellite Report Archive at http://www.ka9q.net/asr-1981.pdf
Later pages of the 1981 ASR archive note that amateurs continued listening to the AO-7 frequencies in the hope it would return. They were reports of a weak beacon carrier in July and August 1981 but although amateurs continued listening nothing was heard in the months after that.
ARRL report June 24, 2002 – It’s Aliiiiive! AMSAT-OSCAR 7 Satellite Returns from the Dead https://web.archive.org/web/20051104135636/http://www2.arrl.org/news/stories/2002/06/24/101/
Oscar 7 Information https://web.archive.org/web/20110605102903/https://www.amsat.org/amsat-new/satellites/satInfo.php?satID=9
Video of 2E0HTS Working the OSCAR-7 Satellite
2010 video of the then AO-7 distance record
‘Getting started on amateur radio satellites’ by G7HIA published in the March 2007 RadCom. Download the article at https://ukamsat.files.wordpress.com/2011/05/satellites_radcom_mar07.pdf
Copyright 2007 Radio Society of Great Britain. For personal use only – no copying, reprinting or distribution without written permission from the RSGB.
Join the AMSAT Bulletin Board AMSAT-BB http://www.amsat.org/amsat-new/tools/maillist/maillist.php
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