Installation
The Duo LNB is normally fitted with the feedhorn for Astra 23.5°E mounted on the dish's feedarm, and the 19.2°E feedhorn sticking out to the right - as viewed standing in front of the dish, with the satellites behind you. The Astra 23.5°E feedhorn is identified with a "23.5" marking on the casing. The dish is then aligned on the 23.5°E position, using a signal strength meter, in the normal way.
The Duo LNB is rotated in the feed clamp to a certain tilt angle to provide both the correct 'skew' angle for the feedhorns to align with the incoming signals, and the necessary height difference between the feedhorns to accommodate the different elevations of the two satellite positions. The correct skew angle and height difference depend on the position of the receive site on Earth's surface, and in most locations the tilt angle from the LNB is a compromise between their ideal settings. However, within Europe the single tilt angle adjustment provides sufficient accuracy for both settings for reliable reception.
The tilt angle for the Duo LNB at the receive site location may be found in maps or city tables (a scale is marked on the LNB casing) or found by adjustment with a signal meter connected.
By setting the correct tilt angle and aligning the whole dish in azimuth and elevation, the two feedhorns of the LNB are optimally aligned for both orbital positions.
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