[amsat-bb] Re: DO-64 observation
lucleblanc6 at videotron.ca
Mon Aug 11 12:20:07 PDT 2008
On 11 Aug 2008 at 15:12, wouter weggelaar wrote:
> 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
Thank's Wouter for your comments.
The change in signal strength appears at TCA exactly at west and it was a southbound pass. I guess the antenna main lobe was directed at me
and when the satelllite passed my TCA point the main lobe was not directed at me.
Half the pass was very good and the other extremely weak i'm using a 14 elem cross yagi stuck in right hand polarisation i know a 3DB
difference due to polarisation change on a yagi but much more when using the wrong polarisation. This old KLM 2M 14C suffer numerous
winters 2 crash down and the relay and the relay board where broken up to a point of no repair the only one solution is to make two
separate antenna. I someone used to modified on of theses old beam it will be interesting to know what the impedance is at the end of the 2
4 to 1 balun? It will be nice if it will be 52ohms! But i guess it is 100 ohms as the 2 balun line are tied to a SO-239 connector.?
The audio quality is nearly as good as FO-29 by the way nice sat to experiment with.
Luc Leblanc VE2DWE
WAC BASIC CW PHONE SATELLITE
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