[NLRS] Re: OSCAR antenna

[Andrew T. Flowers, K0SM]

AO-51 has an uplink on 2m and downlinks on either 435 or 2401 depending 
on which mode is turned on.  As for hearing it, it is currently in 
high-power mode making it fairly easy to hear on omni antennas even with 
the polarization fades.  On 2401.200 (next week) I have been able to 
hear it just fine with a coffee-can (or soup can) antenna and a 
makeshift aluminum horn.  AO51's S-band transmitter is linearly 
polarized, so you will need be able to twist the antenna with this kind 
of setup, much like one does with an "arrow" antenna in mode V/U.  
There's a guy on ebay selling some S-band helices that should work great 
for AO51, and this would eliminate the need for the twisting.  (Look up 
"S-band helix").  He also sells some to feed 2-ft dishes from time to time.

As for the uplink, a couple watts into an omni has worked pretty well 
for me.  You don't need a PL tone when it is in mode V/S.

-Andy K0SM


Mark Oswood wrote:

>There was an article in Mar 2003 QST  called "Work
>OSCAR 40 with Cardboard-Box Antennas!"  I haven't
>built one, but it looked pretty simple.  It is a
>corner reflector made with a cardboard box and
>aluminum foil.  I have to look the article up.  I
>don't remember if this was for V/U or L/S band.  Might
>be an easy way to try things out without a big
>investment.
>
>As for AO-51, I think you can hear it on an
>omnidirectional gain antenna like a J-pole.  See
>
>http://www.amsat.org/amsat-new/echo/Echo_Linkbudget.php
>
>for power calculations.
>
>Of course, if you want to try the microwave downlink,
>you will need a dish or loop Yagi, etc.  I have one of
>the dual-band crossed Yagis from Arrow antenna (3el on
>2 meters, 7el on 70 cm).  This works well for hearing
>the low orbit birds, and can also be used as a
>portable beam for VHF/UHF operations.  I have used it
>to check into the Sunday night net 2 meter net with 5
>watts in the past.  
>
>The problem with the handheld beam is trying to
>coordinate tuning for Doppler shift while aiming the
>antenna by hand.  I think the Ham Radio Deluxe
>software can be set up to auto-tune for Doppler on the
>FT817.  I will probably give this a try when the
>weather warms up a little.
>
>73,
>Mark W0LM
>
>----------------------------------------------------------------------
>  
>
>>Message: 1
>>Date: Tue, 7 Mar 2006 07:09:59 -0600
>>From: "Carl Estey" <cestey at mn.rr.com>
>>Subject: [NLRS] WTB:  S-Band 2401 Mhz Antenna
>>To: <nlrs at mailman.qth.net>
>>Message-ID:
>><000001c641e8$736fc240$6601a8c0 at CAROLNEW>
>>Content-Type: text/plain;	charset="us-ascii"
>>
>>After seeing a message about 2401-Mhz downconverters
>> for sale I have
>>started to consider listening on AO-51 but need an
>>antenna.  Does anyone in
>>the area have any surplus antennas for 2401?  I am
>>also interested in
>>knowing about antennas that are fairly easy to
>>build.
>>
>> 
>>
>>73
>>
>>Carl Estey WA0CQG
>>
>>wa0cqg at arrl.net
>>
>>(952) 250-3110 (Cellphone)
>>
>> 
>>    
>>
>
>----------
>Mark C. Oswood, MD, PhD
>oswoodm at yahoo.com
>
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>  
>




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