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CX2SA > SAT 01.05.05 14:46l 84 Lines 3649 Bytes #999 (0) @ AMSAT
BID : ANS-121.06
Read: GUEST
Subj: ARRL Field Day - AO-51
Path: DB0FHN<DB0THA<DB0ERF<DB0FBB<DB0BI<DB0NOS<DB0EA<DB0RES<ON0BEL<TU5EX<
ON0AR<UA6ADV<CX2SA
Sent: 050501/1238Z @:CX2SA.LAV.URY.SA #:43635 [Minas] FBB7.00e $:ANS-121.06
From: CX2SA@CX2SA.LAV.URY.SA
To : SAT@AMSAT
AMSAT News Service Bulletin 121.06
From AMSAT HQ SILVER SPRING, MD.
May 1, 2005
To All RADIO AMATEURS
BID: $ANS-121.06
For the ARRL Field Day Event this year AO-51 will be configured in
Mode V/S FM Repeater. The uplink will be 145.920 mHz with the 67 Hz
tone enabled.
The downlink will be 2401.200 mHz. There will be two long duration
operating sessions leading up to Field Day when AO-51 will be
configured in Mode V/S to give users the opportunity to test their
Field Day stations. In May there is a 6-day session that has
already been announced via the ANS bulletin and on the AMSAT AO-51
schedule page. In June, AO-51 will also be in Mode V/S the weekend
and entire week before Field Day. Take advantage of these operating
sessions to setup and test your Field Day station before the actual
day arrives.
Working the Mode S downlink on AO-51 does not require a large
investment in equipment for your Field Day station. A satellite
dish is not required to operate this mode. Gould, WA4SXM, copied
the S downlink using just his G3RUH patch feed during the early days
of testing the S band transmitter on Echo. Drew, KO4MA, has
operated portable with a Transystems downconverter using the dipole
feed and a corner reflector on numerous occasions. Mike, KE4AZN,
has operated portable with either a 3.5 turn helix feed (feed only,
no dish) or a homebrew K5OE patch antenna, held out the window of
the car. Mike has also operated mobile on Mode V/S by attaching the
helix feed and downconverter to the trunk of the car. Clare,
VE3NPC, has reported excellent receive signals using a 3.5 turn
helix and a K5GNA downconverter.
Any of these Amsat members can be contacted at their "@amsat.org"
email address and would be happy to help Field Day users get setup
for Mode V/S.
If your IF is on VHF (which most are), an HT or other mobile FM rig
will work fine as your downlink receiver. The large 5 kHz steps of
these radios actually make tuning the fast moving Doppler on S band
much easier.
Use the scheduled Mode V/S sessions to practice before heading out
for Field Day. If you have not worked the S band downlink on AO-51
previously, a few passes monitoring the downlink and practicing the
Doppler correction will be very helpful. The Doppler shift on an
AO-51 pass is approximately +/- 50 kHz. There will be lots of
activity on Field Day, therefore getting your Receive capability
working well before transmitting to the satellite, will keep your
station from causing unnecessary QRM.
The uplink for AO-51 does not require a large Yagi antenna to be
successful. Any good mobile omni direction whip antenna or other
omni directional antenna will work fine, especially if all stations
work together during the passes and not try to dominate the
satellite. Therefore, it should not be difficult to setup an
antenna that will work for the uplink to AO-51. If you have a Field
Day station with Mode V/U capability, you already have the uplink
covered.
A webpage will be setup with a few pictures and text on various AO
-51 Mode V/S station options. This will not include every option
available, but will hopefully assist a new Mode V/S user with some
ideas to get started setting up their station, and show that is it
not difficult to get setup and working the S downlink on AO-51.
Web URL: www.graceba.net/~mkmk518/echofieldday.html
With the V/S configuration of AO-51 and the other satellites
available, we will have a nice compliment of modes to operate during
Field Day.
73 KE4AZN
Echo Command Team
Amsat VP Operations
[ANS thanks the KE4AZN for the above information]
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