Reply to thread

Message

<blockquote data-quote="Vipersan" data-source="post: 888755" data-attributes="member: 325666">I mounted the ESX last night as close to the sweet spot &amp;&nbsp; west of the ESX at the focus ...Although results were better ...still not good.separation roughly 8 degrees ..But then I have proved this to myself in the past realising that if the tripod isn't critically adjusted to place the lnb exactly at the centre (sweet spot)..gain drops off very rapidly.I can only conclude that deep PF dishes either don't perform well on side lobes or noise levels rise quickly away from he focus thus cancelling useful signal levels.Best results for an offset lnb are obtained by moving the lnb a good 10 to 12 degrees off centre ..and NOT aimimg at the dish centre ..but indeed aiming high /low East or West of the centre thus effectively only using a portion of the reflector surface ..Using his method it was possible to lock TPC at 1W at 4.8 db...whereas placed close to the sweet spot and aimed at the dish centre ..No signal whatsoever..I really could do with doing some research on the properties of Deep PF dishes ..but info is difficult to find as they are so unpopular these days..The bit I have found points to such dishes being Lower gain ...narrow beam ...highly critical when pointing..less prone to side lobes ..but very efficient when set up correctly within that narrow beam ..and less influenced by thermal noise (Kelvin)...If anyone wants to chip in with suggestions of info ..a discussion would be both interesting and informative.rgdsVS</blockquote>

[QUOTE="Vipersan, post: 888755, member: 325666"] I mounted the ESX last night as close to the sweet spot & west of the ESX at the focus ... Although results were better ...still not good. separation roughly 8 degrees .. But then I have proved this to myself in the past realising that if the tripod isn't critically adjusted to place the lnb exactly at the centre (sweet spot)..gain drops off very rapidly. I can only conclude that deep PF dishes either don't perform well on side lobes or noise levels rise quickly away from he focus thus cancelling useful signal levels. Best results for an offset lnb are obtained by moving the lnb a good 10 to 12 degrees off centre ..and NOT aimimg at the dish centre ..but indeed aiming high /low East or West of the centre thus effectively only using a portion of the reflector surface .. Using his method it was possible to lock TPC at 1W at 4.8 db...whereas placed close to the sweet spot and aimed at the dish centre .. No signal whatsoever.. I really could do with doing some research on the properties of Deep PF dishes ..but info is difficult to find as they are so unpopular these days.. The bit I have found points to such dishes being Lower gain ...narrow beam ...highly critical when pointing..less prone to side lobes ..but very efficient when set up correctly within that narrow beam ..and less influenced by thermal noise (Kelvin)... If anyone wants to chip in with suggestions of info ..a discussion would be both interesting and informative. rgds VS [/QUOTE]

Verification