Post by Eric Johnston on May 28th, 2008 at 6:12pm
Regarding the connection of an LNB to its waveguide. The rectangles must always match up. Never join up waveguides 'crossed' and make sure any gasket goes in correctly also.
If you are connecting up 14 GHz transmit waveguides, with gaskets, I recommend having two people visually check that the gasket goes in correctly as a crossed gasket could cause several '000$ damage to high power BUCs/HPAs.
You set the receive polarisation by rotating the entire feed and LNB as a whole, in its yoke cradle.
Setting the polarisation is a two step process:
What receive downlink polarisation name have you been told to use?. Horizontal or vertical. Set this name initially, using these diagrams as a guide:
====================================================================
If Vertical, the LNB input waveguide will be like the image above. The internal dipole pin may be above or below; it does not matter.
====================================================================
If Horizontal, the LNB input waveguide will be like the image above. The internal dipole pin may be on either side; it does not matter.
====================================================================
Then apply the polarisation adjustment angle. A positive polarisation adjustment means turn the feed clockwise while facing towards the satellite. A negative polarisation adjustment means turn the feed anti-clockwise while facing towards the satellite. In some cases the entire dish and feed assembly needs to be rotated using a giant polarisation scale behind the dish (HX and Tooway)
Best regards, Eric.
If you are connecting up 14 GHz transmit waveguides, with gaskets, I recommend having two people visually check that the gasket goes in correctly as a crossed gasket could cause several '000$ damage to high power BUCs/HPAs.
You set the receive polarisation by rotating the entire feed and LNB as a whole, in its yoke cradle.
Setting the polarisation is a two step process:
What receive downlink polarisation name have you been told to use?. Horizontal or vertical. Set this name initially, using these diagrams as a guide:
====================================================================
If Vertical, the LNB input waveguide will be like the image above. The internal dipole pin may be above or below; it does not matter.
====================================================================
If Horizontal, the LNB input waveguide will be like the image above. The internal dipole pin may be on either side; it does not matter.
====================================================================
Then apply the polarisation adjustment angle. A positive polarisation adjustment means turn the feed clockwise while facing towards the satellite. A negative polarisation adjustment means turn the feed anti-clockwise while facing towards the satellite. In some cases the entire dish and feed assembly needs to be rotated using a giant polarisation scale behind the dish (HX and Tooway)
Best regards, Eric.