Lincoln Calibration Spheres were launched in the 60s and are still used today to calibrate ground radar systems. But they are entirely passive (think very expensive hollow metal spheres).
GEOS-3 launched four years after AO-7, and lead a very active RF life up until was decommissioned in 2016. It is still in orbit and people use it as a test for laser ranging devices -- again passive, and not as old anyway.
I believe that AO-7 is indeed the oldest satellite that has an active RF purpose.
73, Bob, WB4SON
On Wed, Jul 3, 2019 at 11:56 AM Mike Seguin via AMSAT-BB amsat-bb@amsat.org wrote:
Hi Graham,
If you like, you could mention that AO-7 was commanded successfully for the first time after it returned on July 11, 2002. The Command sent was to change the speed of the CW beacon. It worked!!
Mike, N1JEZ
On 7/3/2019 10:52 AM, Graham Shirville via AMSAT-BB wrote:
Hi All,
I am preparing for a satellite talk and QO100 demo this Monday 8th July at the Milton Keynes Amateur Radio Society!
I have a slide that shows Oscar 7 as having been launched in 1974 and I am tempted to state that it is the oldest satellite in earth orbit that is still functioning! (not just the oldest Oscar) Would I be correct?
I will, of course, explain about how it was "out of service" for some years in the intervening 45.
many thanks
Graham G3VZV
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73, Mike, N1JEZ "A closed mouth gathers no feet" _______________________________________________ Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: https://www.amsat.org/mailman/listinfo/amsat-bb