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HX50 W3A  7E  S=82 and Q=70, no higher.

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Jun 6th, 2009 at 5:40pm  
I Have a Horizon HDSM USB Plus satelite meter and we are pointing at EutelsatW3 @ 7E with a 1.2M dish. We recieved all the equipment new from Bentley Walker new in the last week. I'm involved on pointing all three systems that we purchased and are having trouble peaking our dishes above 82 S and 70 q.  

This is how our dishes are pointed now.
  Dish Azimuth of 239 Deg
  Dish Elevation of 33.5 Deg
  Polarization angle of 48 deg and the dish was turned  
  Clockwise when facing the satelite.
  The outdoor LNB on the feed arm was setup for
  Horizontal nominal polarization.
  Our Location is N30 33 and E 047 40

The data from Bentley Walker told us to point at W3 @ 7E with a recieve Pol of Horizontal. A Sat freq of 11272 and symbol rate of 13000000. DVB Mode: DVB S2 ACM and frequency band of KU/QPSK

We have already commisioned our Hughes HX50 Modem on all three systems after getting a lock of 82 on S and 70 on q. I have spent a total of 5 hours trying to peak up our dish even more trying to get our S above 89 and or q higher.

Our download speed is great and usually hovers around 1.2 Mbs but our upload speed comes in around 25-45 Kbps or less.

We are on the BENTLEY HX Corporate Premium plan and the typical speeds should be around 900-1200 Kbps down and 120 Kbps up. The advertised max burst are 2048/512. I'm aware of the HX grade of service and we currently not being throttled down.

We have three seperate systems that I help set-up with nearly the same max Q & S values.

Does the low Q & S values play a role in the low upload speeds?

Any suggestions or help would be greatly appreciated.

Thanks in advance,
Dave
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« Last Edit: Jun 8th, 2009 at 11:24am by Admin1 »  
 
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Eric Johnston
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Reply #1 - Jun 7th, 2009 at 12:53pm  
1.  If you have the 1.2m antenna with the giant polarisation scale on the back of the dish you should be using the scale on the back of the dish to set the polarisation.  

For horizontal polarisation, the LNB should be exactly away from the feed support arm.  The fat lump on the horn throat must always be towards the feed arm and 505 on the feed throat must always be directly away from the feed support arm.

2.  It is possible that peaking the polarisation (now +48 deg) may help.

I believe that W3A is tilted clockwise 3.5 deg.  If so, you might get a negligible improvement by trying +51.5 deg.

3.  A third, unlikely, possibility is some systematic focus error, like wrong length feed support struts or wrong holes being used in the BUC support plate.

If you think this may be the problem please take a picture of the dish from an exact side view, with the camera in line with the two side strut attachment points,  so I can measure the position of the circular feed relative to the dish.  Alternatively tell me the four measurements from the top and bottom of the curved dish to the top and bottom of the feed window, and the Prodelin model number of the antenna.

Best regards, Eric.
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« Last Edit: Jun 7th, 2009 at 9:40pm by Eric Johnston »  
 
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Reply #2 - Jun 7th, 2009 at 7:28pm  
Eric, Thanks for the response.

1.) We do have the 1.2 M dish with the large polarization scale on the back and we did use it to set the +48 Deg angle. After I peaked the Azimuth and elevation, I then peaked the Polarization Angle. I utlized the same method as I did on the azimuth and elevation, by going to equal values on both side and set the peak value for polarization.

2.) I have read a lot of your articles that you have provided and I truly believe I have set the nominal recieve polarization to Horizontal, just as you described in your reply to my post here. For horizontal polarisation I placed  the LNB exactly away from the feed support arm.  The fat lump on the horn throat is towards the feed arm and 505 on the feed throat is directly away from the feed support arm.

3.) We are located in Basrah, Iraq. I have confirmed the coordinates with a GPS and the Azimuth, Elevation, & Polarization angle checked out.

4.) The feed arm only allowed one way to place the BUC support plate on the feed arm. It is dark here now, so I will provide the measurements that you requested and they are listed below.
From the bottom of the dish to bottom of feed window=87.6 cm and from the top of the dish to the top of the feed window=128.3

I can not find the Prodelin model number of the antenna, but it is the exact same one in the article you wrote about the HughesNet HX VSAT terminal installation.  The only thing I could refernece is that it is a 1.2 Meter Prodelin Antenna new from Bentley Walker. I have the LNB Serial number and the serial number off of the BUC support plate if you need it.

Thanks again for your help.

Dave

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Eric Johnston
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Reply #3 - Jun 8th, 2009 at 8:10am  
I agree on the pointing and polarisation angles.  I have edited my message above.

Assembly manual for 1135 antenna
http://www.gdsatcom.com/Prodelin/Technical_Docs/assembly_manuals/4096-662.pdf

THE ABCD measurements for Prodelin dishes are listed here:
http://www.gdsatcom.com/technicaldocuments.php#geometry

The link below relates to 1.2m dish, f/d=0.8, feed 39 deg and 5.76 in dia.
http://www.gdsatcom.com/Prodelin/Technical_Docs/feed_location_drawings/td0316.pd...

A= 33.72 in = 85.64 cm  
B= 36.97 in = 93.90 cm
C= 51.54  in = 130.9 cm
D= 48.28 in = 122.63 cm

=========

My 1.2m HX dish had the following measurements:
Feed diameter 14.2 cm = 5.59 inches
Overall dish dimensions 123 cm wide x 137cm high
Curved surface 120.7 cm wide x 126.5 cm high.
A=  85.6 cm
B=  93.6 cm
C= 131.2 cm
D= 123.2 cm

...
...

==========

Your measurements
A= 87.6 cm  Comment: This is too long and could be a real error. Check your white yoke is in the same position as per my picture above. There are several pairs of holes where the white yoke fixes to the grey plate.
D= 128.3 cm  Comment: This is too long but could be due to you measuring from the top of the dish rather than from the top of the curved surface.

Please check your measurements are from the edge of the curved surface to the feed window edges.  There may be hemispherical depressions in the dish where the reference points are defined.

One last thought.  It may simply be that Eutelsat have readjusted the outlink carrier power from the hub.  When I set up my dish the carrier was rather 'hot' and the power seemed unnecessarily high.  They may have just adjusted it to a more reasonsable level.  It won't make any difference to your browsing speeds.

Best regards, Eric.
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« Last Edit: Jun 8th, 2009 at 11:19am by Eric Johnston »  
 
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Reply #4 - Jun 9th, 2009 at 7:13pm  
Eric,

Thanks for your help. The measurements all checked out. I will visit with Bentley Walker on the Browsing speeds.

Dave
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