[amsat-bb] Re: Delfi C3 transponder frequencies ?

Alan Cresswell alancresswell at xtra.co.nz
Mon Jul 28 15:38:10 PDT 2008

Hi David and Ib,


Delfi transponder was operating over ZL on the 2132 UT pass a short while


Started with a 6.3kHz offset (Satellite input on 435.5495MHz, Output on
145.9068MHz).  This drifted down to about a 6kHz offset at the end of the

Good beacon signals until Delfi was about 61 deg S  when it sounded as
though it was FMing and the note became rough for about 2 minutes.

Little or no signal back from the transponder.

It recovered before LOS a few minutes later.

Note that Delfi has been in full sun for more than half its orbit before it
hits ZL and progressively loses the sun before going into eclipse South of
ZL so the above may not represent what happens as Delfi comes out of eclipse
in the Northern hemisphere.


All very interesting.  Still no one to talk to in this part of the world.
"Heard in VK" is the best so far.  Next pass is 4 Deg low to West (over VK)
so perhaps this time if the transponder is still on.






From: G0MRF at aol.com [mailto:G0MRF at aol.com] 
Sent: Monday, 28 July 2008 13:37
To: alancresswell at xtra.co.nz; oz1my at privat.dk
Subject: Re: [amsat-bb] Re: Delfi C3 transponder frequencies ?


Hi Alan / Ib


I never thought I would say this.....but part of the answer is on you tube.





If you watch the video carefully, then you can see with a little stopping
and starting the two frequencies on their radio when they were testing the
transponder.  It's about 1min 20sec into the video.


145.9005  =  435.5512


So that would seem consistent with Alan's observation and equating to a
nominal clean room temperature.   However, certainly seems to be that an
offset has been there from the moment the transponder was finished.









In a message dated 27/07/2008 20:27:18 GMT Standard Time,
alancresswell at xtra.co.nz writes:

Hi all,

On the one good pass over ZL so far I had to use a +6kHz offset on my uplink
to receive on the nominal downlink frequency.
i.e. satellite input frequency of 535.556 (nominal 435.550) to hit the
145.900 satellite output frequency.



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