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CX7BY > SAT 13.06.04 05:51l 52 Lines 2368 Bytes #999 (0) @ AMSAT
BID : ANS-165.03
Read: GUEST
Subj: SO-50 Turn-on Procedure Released
Path: DB0FHN<DB0RGB<OE5XBL<OE5XBR<ON0AR<ON0AR<7M3TJZ<CX2ACB<CX7BY
Sent: 040613/0328Z @:CX7BY.MVD.URY.SA #:16210 [Montevideo] FBB $:ANS-165.03
From: CX7BY@CX7BY.MVD.URY.SA
To : SAT@AMSAT
AMSAT News Service Bulletin 165.03 From AMSAT HQ
SILVER SPRING, MD. June 13, 2004
To All RADIO AMATEURS
BID: $ANS-165.03
Robin Haighton, VE3FRH, President of AMSAT-NA reports that, "I have been
advised that I can now publish the tone to allow all users to open SO-50 as
the power availability appears to be good."
The order of operation is thus (allow for Doppler as necessary):
1) Transmit on 145.850 MHz with a tone of 74.4 Hz. This will arm the 10
minute timer on board the spacecraft.
2) Now transmit on 145.850 MHz (FM Voice) using 67.0 Hz to PTT the
repeater on and off within the 10 minute window.
3) Sending the 74.4 Hz tone again within the 10 minute window will reset the
10 minute timer.
Drew Glasbrenner, KO4MA, a member of SO-50's command team adds, "Please!!!
All new users, be VERY SURE that your equipment is good enough to hear the
satellite before attempting to enable it with the 74.4 Hz tone." He asks
that, "If you have any doubts at all, let someone else turn it on." Drew
noted that, "What will be disastrous is if some of the users that have
marginal receive systems spend half the pass transmitting the 74.4 tone at
50 watts. 2 seconds is enough, and the receiver is VERY sensitive."
The spacecraft repeater consists of a miniature VHF to UHF repeater with a
receive sensitivity of -124 dbm, having an IF bandwidth of 15 kHz. The
receive antenna is a 1/4 wave vertical mounted in the top corner of the
spacecraft. The receive audio is filtered and conditioned then gated in the
control electronics prior to feeding it to the 250 mW transmitter. The
downlink antenna is a 1/4 wave mounted in the bottom corner of the
spacecraft and is canted at 45 degrees inward.
Also, for those trying this sat out for the first time, bear in mind that
with a single 1/4 wave whip for the downlink transmitter on the satellite
you will experience occasional severe fades caused by A) cross polarization
if using a linear antenna or B) the spacecraft body blocking your view of
the antenna. Blocking happens even with large AO-13 class stations with a
preamp. Drew concluded saying "This week I've noticed the downlink is
particularly good at the beginning of the ascending passes, and not so good
near the end of the pass."
[ANS thanks Robin, VE3FRH and Drew, KO4MA for the above information]
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