[amsat-bb] Re: DO-64 observation

wouter weggelaar wouterweg at gmail.com
Mon Aug 11 06:12:56 PDT 2008

Hi Luc,

Thanks for your report here on the BB,
Did you try to switch your polarization between LHCP and RHCP?
As Delfi-C3 goes over the earths poles, it flips itself 180 degrees in
Z axis (perpendicular to earth). Otherwise one side will be always
exposed to sunlight and things might run hot / degrade in time.
Due to this flip, the polarization sense changes depending on which
pass you are tracking (ascending from south to north, or descending
from north to south)
If you do not switch polarization sense, you can observe big
differences between those two.
Please bear in mind that Delfi does not have any active attitude
control system and solely relies on passive stabilization.
During a pass, polarization might change due to slow rotations. You
could try to switch polarization within a pass and see whichever is

Delfi-C3 does have an RF AGC within the IF-stage, so uplinking more
power than necessary only limits other weaker stations and does not
improve your own signal.

We received some reports about people uplinking using a FT817 with
abt. 5 Watts into an arrow antenna, so your 1 or 2 watts with a good
antenna could do miracles...;)
Reports of Delfi-C3 (DO-64) transponder operation are greatly
appreciated and can be sent to info at delfic3.nl or via the BB.

On behalf of the Delfi-C3 team,

Best 73's

Wouter Weggelaar
Delfi-C3 Command Team

On Sun, Aug 10, 2008 at 5:58 PM, Luc Leblanc <lucleblanc6 at videotron.ca> wrote:
> First experience with do-61 (DELFI C-3) this morning here.
> 1-No body was on the satellite only me calling CQ
> 2-From AOS to TCA signal was very good about +-3 DB above noise level
> 3-At TCA signal dropped below noise level too week for SSB but week for CW
> 4-From TCA to LOS signal remain below noise level and became too weak even for CW
> I suspect the satellite antenna configuration show some directivity or it is the satellite attitude who seems to favour some part of the
> orbit pass? I was never able to received my SSB dowlink on the eastern pass only a week CW carrier one time. There is some audio AGC as
> increasing the audio level make's not a big change on the dowlink. I was able to uplink with the FT-847 RF gain control completely turned
> off (about 1 or 2 watts).
> I don't know if my results are in line with what the team planned but when the sat was on data mode i was able to copy it from AOS to LOS
> but i think the TX power is reduced in transponder mode?
> It make's another one to experiment with and a preamp is imperative to be able to work it with ease. Just have to get some folk's on it
> here to be able to check it again.
> "-"
> Luc Leblanc VE2DWE
> Skype VE2DWE
> www.qsl.net/ve2dwe
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