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DISH SETUP: Single sat, Multi-Sat & Motorised
C-Band Reception, UK and Europe
T plate ...Open T ....Hybrid T..
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<blockquote data-quote="Vipersan" data-source="post: 802872" data-attributes="member: 325666"><p>OK ...just got home from work ..and the first thing I did after my cup of T ...A question of priorities...was to remove another 1cm of poyethylene from the open section of the T ..so now only 1cm of complete cross section plate is actually inserted inside the LNB throat.</p><p>You'd think it would no longer de-polarise circular signals..</p><p>You'd be wrong ..</p><p>..as I said ..I'm convinced you can de-polarise _outside_ the lnb itself..</p><p>So more proof and this process of comparison is a bit more scientific.</p><p></p><p>First the dish was moved to 1 West ..and the Pentagon Channel selected ..</p><p>The 3 plates were readied ...A full T ...An Open T ..and a commercial dielectric plate supplied with a new lnbf.</p><p>OK ..</p><p>The commercial plate was tried ..and a signal level of 5.1 db photgraphed..</p><p>Next ..a Full T plate ..</p><p>6.9db..which is a bit of a record for me..but maybe conditions were good today..</p><p>Next the Open T of which only 1cm of full cross section polyethylene is physically inside the lnb throat ..</p><p>6.3 db ...</p><p>So thats a drop of 0.6db on a full T .</p><p></p><p>Next the dish was swung over to 37.5 W ...and silverbird ...and then Metro were tested ..</p><p>First with no plate at all ..</p><p>Silverbird (Locked) 8.8db ..</p><p>Metro (Locked) 13 db</p><p></p><p>then the Open T was inserted </p><p>Silverbird (Not Locked ) 6.3db</p><p>Metro TV (Locked) 11.2 db</p><p></p><p>So it looks like the open T continues to do its job on circular signals with a roughly a0.6 to 1db drop in gain</p><p>Whereas Allowing access to linear with the Open T in place reduces signal by approx 2 to 3 db as expected..</p><p>This fact means its useless I guess ...except on BUD type dishes ..</p><p>But ...it does appear to work ..and is reasonably consistant.</p><p>No use for signal that are threshold ..but high power signals ...maybe very useful as a cheap way to achieve both circular and linear with a single plate inserted.</p><p>There are variations with regards to linear ..for example Jamaica TV at 55W ...is only reduced from 6.5db to 4.5 db..</p><p>So I assume frequency modulation type and symbol rate etc ..also play a part.</p><p>I hope someone else tries this as its inexpensive ..and the more info the better.</p><p></p><p>In Short you stand to lose approx 2 db on linear signals ...and 1db on circular ...with the OPen T in place..</p><p>rgds</p><p>VS</p><p>Here are the pics</p></blockquote><p></p>
[QUOTE="Vipersan, post: 802872, member: 325666"] OK ...just got home from work ..and the first thing I did after my cup of T ...A question of priorities...was to remove another 1cm of poyethylene from the open section of the T ..so now only 1cm of complete cross section plate is actually inserted inside the LNB throat. You'd think it would no longer de-polarise circular signals.. You'd be wrong .. ..as I said ..I'm convinced you can de-polarise _outside_ the lnb itself.. So more proof and this process of comparison is a bit more scientific. First the dish was moved to 1 West ..and the Pentagon Channel selected .. The 3 plates were readied ...A full T ...An Open T ..and a commercial dielectric plate supplied with a new lnbf. OK .. The commercial plate was tried ..and a signal level of 5.1 db photgraphed.. Next ..a Full T plate .. 6.9db..which is a bit of a record for me..but maybe conditions were good today.. Next the Open T of which only 1cm of full cross section polyethylene is physically inside the lnb throat .. 6.3 db ... So thats a drop of 0.6db on a full T . Next the dish was swung over to 37.5 W ...and silverbird ...and then Metro were tested .. First with no plate at all .. Silverbird (Locked) 8.8db .. Metro (Locked) 13 db then the Open T was inserted Silverbird (Not Locked ) 6.3db Metro TV (Locked) 11.2 db So it looks like the open T continues to do its job on circular signals with a roughly a0.6 to 1db drop in gain Whereas Allowing access to linear with the Open T in place reduces signal by approx 2 to 3 db as expected.. This fact means its useless I guess ...except on BUD type dishes .. But ...it does appear to work ..and is reasonably consistant. No use for signal that are threshold ..but high power signals ...maybe very useful as a cheap way to achieve both circular and linear with a single plate inserted. There are variations with regards to linear ..for example Jamaica TV at 55W ...is only reduced from 6.5db to 4.5 db.. So I assume frequency modulation type and symbol rate etc ..also play a part. I hope someone else tries this as its inexpensive ..and the more info the better. In Short you stand to lose approx 2 db on linear signals ...and 1db on circular ...with the OPen T in place.. rgds VS Here are the pics [/QUOTE]
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Satellite TV receivers & systems support forums
DISH SETUP: Single sat, Multi-Sat & Motorised
C-Band Reception, UK and Europe
T plate ...Open T ....Hybrid T..
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