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AO-40 Update, 2004-02-03



Stacey;
Are there any environmental conditions which could be exploited in
getting the voltage high enough to activate the relay. For example, if
the spacecraft were coming out of an eclipse and were very cold, would
the solar panels be more efficient and the relay coil having lower ohmic
losses, could there be a chance of toggling the relay?

Thanks Joe

Date: Mon, 02 Feb 2004 21:59:04 -0500
From: "Stacey E. Mills" <w4sm@AMSAT.Org>
Subject: [amsat-bb] AO-40 Update, 2004-02-03

The AO-40 command team has established a routine of trying to cycle the
main battery off (aux. battery on)  and then the S2 Tx ON every orbit,
using simple machine codes.  Following this, the sequence to disconnect
all
transmitters is sent, to protect them from low voltage.  If we have
approximately 10 volts on the main buss, then these commands should be
making it through, but the S2 transmitter was not designed to run below
20
volts and is not coming on.  The battery relay has been tested in the
amsat
lab, where a duplicate exists, and it will cycle reliably at 12 volts,
but
not lower.   If we have less than 10 volts, then the commands will not
be
received because the IHU-1 and/or command receivers are insufficiently
powered.  Either way, the IHU-1 is not currently running IPS.  The
machine
code commands only function in reset mode.   We assume that we currently

have less than 12 volts and that either the IHU-1 and relay are not
functional (<10 volts) or the relay isn't functional (<12 volts),
because
cycling the relay should get us out of this situation by disconnecting
the
main battery.

(snip)

- --W4SM for the AO-40 Command Team



--
Joe Leikhim K4SAT


"Jazz is not dead.  It just smells funny." -F.Z.


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