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Re: R: looking higher..10GHz?



Hi Dom,

I answered Mark, as well.  I suggested that feedhorn might match an
offset-feed dish fairly well, but wondered whether he might need circular
pol.  As you know I am going to build a 10-GHz septum feed so we will see
how that idea works out.

I noted the strange uplink freq of 2560 MHz but assumed that was a
non-amateur frequency to be used by P5A staff.  I don't believe that
Amsat-DL will want anyone transmitting on the uplink as I suspect this to
be used for command of the Mars mission.  My take of 10.450 GHz is that it
will be utilized for scientific data/telemetry feed from Mars on the P5A
mission.  It will be a receiving opportunity for hams vs. an operational
transponder link.  

But I could be wrong.  Perhaps someone from P3E will comment?

73's Ed - AL7EB

At 02:49 PM 3/20/2005 +0100, i8cvs wrote:
>Hi Mark, N8MH
>
>2560 MHz (S) uplink for P5-A Transponder Experiment on board of P3-E
>is not a correct frequency because the maximum allowed frequency for the
>Amateur Satellite Service is 2450 MHz as showen in the frequency table
>planned for P3-E wich is available in the AMSAT-DL site at
>
>http://www.amsat-dl.org/p3e/tabelle.htm
>
>About the feed on the ebay it is a rectangular feed horn made for 10368 MHz
>with a gain of 9 dB so that it is good to illuminate a dish with a F/D ratio
>of 0.6 like an offset dish as you can calculate and verify using the program
>HDL_ANT  version 3b3 from Paul Wade W1GHZ (N1BWT)
>
>On the other side the above feed horn is linearly polarized and it is ideal
>for 10 GHz tropo communications at 10368 MHz
>
>For satellite applications with 10450 MHz downlink of AO40 I have built
>a Chaparral feed using a circular waveguide with two SMA coaxial to
>wavelenght transitions to get RHCP and LHCP because at the time of
>construction the direction of circular polarization for the X band antenna
>on AO40 was not available.
>
>I have the above Chaparral feed on a 60 cm prime focus dish with F/D= 0.38
>with a home built low noise HEMT preamplifier and I actually get 3.5 to 4
>dB of sun-noise with a solar flux in the average of 108 sfu at 2800 MHz
>during the last week.
>
>Unfortunately due for the X band TX failure on AO40 I never had the chance
>to test the above setup on satellite except for sun-noise experiments.
>
>For 10450 MHz I have built a transverter from a Kit for 10368 MHz sold by
>DB6NT changing the XTAL local oscillator and retuning it to get in frequency
>10450-10452 MHz with an IF from 146 to 148 MHz using obviously only
>the receiving part of it.
>
>When P3-E will fly I will be ready but I belive that to became a reality in
>2005/2006 P3-E needs generous donations from the amateur community
>otherwise........come back to the HF or use the BB to communicate
>worldwide.
>
>I hope this help
>
>73 de
>
>i8CVS Domenico
>
>----- Original Message -----
>From: Mark L. Hammond <mlhammond@charter.net>
>To: Amsat List <amsat-bb@amsat.org>
>Sent: Sunday, March 20, 2005 2:03 AM
>Subject: [amsat-bb] looking higher..10GHz?
>
>
>> I saw this tonight:
>>
>http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=1502&item=5761236048&;
>rd=1
>>
>> Also, please consider the following from:
>http://www.amsat.org/amsat-new/express/
>> P5-A Transponder Experiment: 2560 MHz (S) uplink and 10450 MHz (X)
>downlink. Also usable as a linear
>> transponder with approximately 50 KHz bandwidth.
>>
>> Inasmuch as P3E is destined to have 10GHz down, I wonder what type of dish
>might match up with this feed?  It seems like a very inexpensive feed, if it
>makes sense to consider.  If not, it's like throwing money away ;)
>>
>> Can anyone share their thoughts on this feed and what type of dish might
>match up?  (Of course, the issue of a 10GHz downconverter comes to mind,
>too!!)
>>
>> Thanks,
>>
>> Mark L. Hammond  [N8MH]
>> ----
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>----
>Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
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----
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