What dish with quattro LNB? Help?!!

[joenitro]

Hi all,
Would appreciate a little guidance/help from you on this as I am a novice with this stuff, as will no doubt become apparent when you read the text below

Having just converted a 60cm zone 2 dish from a quad LNB to a Triax quattro LNB and Vision V5-512MP multiswitch setup (so I can eventually feed more flats on the estate after digital switchover), I am having some slight signal issues.

On the original setup, my (then) Sky HD box would always give about 80-90% signal strength and 90 - 100% quality on all channels - no dropouts in bad weather etc. and I was very happy. The flat above me (using the other two feeds from the quad LN were also happy with their signal with no reported dropouts, even in bad weather. That dish and LNB etc ran perfectly for 18 months.

However, since changing to the quattro LNB and multiswitch, but keeping the same dish, the flat above (that still have Sky and therefore more channels than I do!) have reported some channels dropping out intermittently and going 'blocky' etc. I have also noticed it a couple of time on recorded programs from BBC1 HD. Bit odd as that gives about 90% strength and 100% quality on my current Foxsat HDR box.

Have checked alignment with a proper installers meter this evening again and all seems OK.
I have one theory though: can the Triax quattro LNB be used with a "Sky zone 2 60cm dish" of the 'oval shape'? Have been researching online and seen a couple of posts mentioning that quattros should only be used with round dishes due to scaling rings in the LNB.

Please could anyone advise?

Joe

 

[Lazarus]

Two points: First you are right that inefficiency is introduced by the mismatch of feedhorn shape/dish shape. Second, you generally need to step up a dish size when using a Quattro. Perhaps 80cm?

 

[joenitro]

Two points: First you are right that inefficiency is introduced by the mismatch of feedhorn shape/dish shape. Second, you generally need to step up a dish size when using a Quattro. Perhaps 80cm?

Wow, thanks Tivù for the super-rapid reply!!
Well, the LNB mismatch was only a guess really, as I was struggling to find any confirmation of whether that WAS the case or not! Is that a fact then? i.e. is any quattro LNB simply 'not recommended' for an elliptical dish like mine?

 

[Robbo]

Yes, it is correct, there are no quattro LNBs for Sky type dishes. Sky LNBs with feedhorns designed for Sky minidishes ideally only should be used. Apart from that, it is usual to up the dish size a little when using a quattro. A triax TD78 or maybe a Penta 68cm should do the job. A Hirschmann 85cm is another really good choice, and should give an almost cast iron signal.