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Wildblue / Hughes Ka LNB polarity switching?

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Ex Member
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Aug 23rd, 2010 at 4:03pm  
Hi folks,

I have a Ka band LNB which is from the Hughesnet  / Wildblue system. It has H and V waveguide inputs on the front side and an output F -type for IF / volts. I have tried adding 22KHz tone, and 13/18v but cannot get the LNB to switch polarity. I have a picture of the relevant LNB, its pcb etc at http://www.uhf-satcom.com/kaband/

Would any of the WildBlue experts be able to tell me what the receiver / modem outputs to change polarisation?

On a related topic, where does one get hold of the depolarisor and Ka-Band feed horns?

thanks and regards,

Paul
http://twitter.com/UHF_Satcom
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Ex Member
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Reply #1 - Aug 23rd, 2010 at 5:40pm  
Wildblue and HughesNet do not use the same Ka-band TRIA. Can you be more specific as to which one? I'm thinkin' it's probably one of the older WB rigs. That Monolothics transceiver uses linear polarization. But it's converted to circular by means of an external cast polarizer positioned between the OMT/filter and the feedhorn. Polarization is subsequently changed between left hand and right hand by physically rotating the cast polarizer

//greg//
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Reply #2 - Aug 23rd, 2010 at 6:32pm  
Hi there, thanks for the reply. As far as I can see, the LNB used a separate depolarisor assembly, along with an OMT.

I got the LNB off ebay, and have retuned it to the 20.2 to 21.2GHz downlink band, where its working really well. The actual LNBs I got are the same as on eBay "Hughes Net Satellite LNB FSS 19.7 20.2 Ghz 15008250005" - I could not find much in the way of technical spec on them, but I'm guessing the noise figure is around 1.5dB based on the front end device.

I've looked at the PCB and on the DC supply input, you can clearly see there is a R/C filter and some transistor switching, so its clearly some tone / signal that needs to be added to the DC feed in order to get the unit switched to the other polarity.

We dont have WildBlue here in the UK, so its pretty hard to find info / used parts to play with, but we do have quite a number of Ka band satellites.

regards,

Paul
http://twitter.com/UHF_Satcom
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« Last Edit: Nov 17th, 2014 at 9:28pm by Admin1 »  
 
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Reply #3 - Aug 23rd, 2010 at 7:14pm  
Once it is resolved clearly by the OP if this is  Hughes or Wildblue part please go back and edit your posts to remove the wrong name.

I'm thinking it is Hughes, not Wildblue.
Note this picture says Hughes, not Hughes Net
...
I think the ebay ad is wrong to include the word "Net".

The Wildblue TRIA is an integrated device with transmit on one polarisation and receive on the other. In the US a polariser is inserted to make LHCP/RHCP or RHCP/LHCP.  In Europe (called Tooway) the polariser is not used and the system operates linear polarisation.

Best regards, Eric.
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« Last Edit: Aug 23rd, 2010 at 8:43pm by Admin1 »  
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Reply #4 - Aug 23rd, 2010 at 7:32pm  
Apologies, I responded to a post in the USA/Canada forum, without checking the location in your profile. But at the same time I was not aware that HYLAS1 had even launched yet, much less gone operational to the point of actually serving subscribers. HughesNet Ka-service to the CONUS uses circular polarization. If HYLAS Ka-band uses linear, then disregard my earlier response.

Note also Eric, the physical similarity between what you identify as TooWay Ka-band hardware: http://www.satsig.net/tooway/tooway-satellite.htm and the Wildblue/TeleSat units that are used here in the colonies: http://www.wildbluetools.com/content/dealer/photos/images/equipment/WildBlue-dis...

//greg//
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