1.8m prime focus dish.-The focal distance available after assembling the LNB arms to the dish is no where near what we calculate it should be or what your own (Spanish) instruction sheet says it shoul
The type of LNB being installed is very important.
All our prime focus dishes feature in their LNB arms, 3 adjustment screws+whasers. It seems something unnecessary, but they are very important since they allow adjusting the right focal distance for any of the LNB&feedhorns available in the market, I mean, not matter the length of the LNB feeder it can be installed in the dish to the right focal distance.
Next figure shows the focal distance adjusted to the theoretical value of the 1.8m dish: 756mm. In this case it is being using a typical single prime focus feeder, Televes ref. 9344.
Our prime focus dishes can also be used with LNBs designed for offset dishes (once accepted the inherent losses) by substituting the the previous single feeder support by a new one, Televes ref. 7509, specific for offset LNBs. These LNBs feature larger feeder than the prime focus ones. Next figure shows how the same theoretical focal distance for this 1.8m dish can be achieved with an offset LNB.
In your complaint, the error incurred during the installation is too high, so that we belive the LNB has been installed without keeping in mind the above mentioned considerations, I mean just tightening the screws to the top, as can be seen in the figure that follows.
Therefore, there is no mistake with the LNB arms. The length of each arm you have mentioned is correct: 785mm