[Moon] 3 cm circular polarisation

[Peter Hansen]

Hi there gang. Many of us use old used dished that was used in satellite service in X and Ku band. The feeds we have are optimized for the particular dish. I tried many other feeds but only the one build for the dish really makes a good performance. So why go for worse performance if it is not nessesary.
That was just my 50 cent on the topic.
73 Peter OZ1LPR

From: Moon [mailto:moon-bounces at moonbounce.info] On Behalf Of Dom DEHAYS
Sent: 21. september 2014 20:59
To: SM6CKU; Moon-Net; moon at moonbounce.info
Subject: Re: [Moon] 3 cm circular polarisation

Hi Ben ,

of course , there's no pb for U to use what U want. Just one thing : 0,5db loss in front of the preamp is NOT 0,5db loss on signal , but probably closer to 1dB....so your monn noise could be 3dB.and something like 2dB more on sun noise

73
Dom
----- Original Message -----
From: SM6CKU<mailto:ben at sm6cku.se>
To: Dom DEHAYS<mailto:f6dro at wanadoo.fr> ; Moon-Net<mailto:moon-net at mailman.pe1itr.com> ; moon at moonbounce.info<mailto:moon at moonbounce.info>
Sent: Sunday, September 21, 2014 8:44 PM
Subject: Re: [Moon] 3 cm circular polarisation

Dom,
My preamp (DB6NT) has a NF of 0,75 dB, the SMA to SMA male connector is 0,1 dB, the isolation relay is 0,15 dB and the coax between relay and LNA is 0,15 dB. A total of 1,15 dB which has been confirmed by measurements. I agree that a WG version will improve these figures, but I prefer not to use WG pieces. I can accept the 0,5 dB loss compared to that solution. 2,5 dB of moon noise instead of 2.
But this has nothing to do with linear or CP....
I will try to take some photos tomorrow.

73 de Ben
----- Original Message -----
From: Dom DEHAYS<mailto:f6dro at wanadoo.fr>
To: SM6CKU<mailto:ben at sm6cku.se> ; Moon-Net<mailto:moon-net at mailman.pe1itr.com> ; moon at moonbounce.info<mailto:moon at moonbounce.info>
Sent: Sunday, September 21, 2014 12:15 PM
Subject: Re: [Moon] 3 cm circular polarisation

Hi all ,

I have no personnal objection to go CP on 3cm eme BUT it should be done with a waveguide access on the RX side of the feed.Most feeds with a polarizer I have seen yet use an SMA connector on the RX side , it is a problem as we need to use a coaxial sma relay for isolation and a cable ( and/or adapter(s)) to connect a coaxial preamp . This will give  significantly reduced Rx performances compared to a waveguide system.

73
Dom

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.moonbounce.info/pipermail/moon/attachments/20140922/c8d65b03/attachment-0001.html>