Postioning LNB

[martinw01908]

Hi

I have just bought a 90cm Triax dish with a grey 0.6 MTI LNB. I am a bit of a newbie at this. There is some variation on how far the LNB should stick out from the plastic clamp. Where should it be clamped? As near to the plastic cap end as possible, in the middle or nearest the coax end??
This adjustment defines the amount that the LNB sits away from the dish so is this crucial or doesn't it matter. If it does matter where should it be?

I would try to draw what I describe but all I can come up with in text is this below. I hope you can understand it!!!!


I I----I--I--
I I LNB
I I----I--I--COAX END
CAP C
END L
A
M
P

Would be grateful of any help. At the moment I am just trying to align it without a motor...that comes later, when i have tried different sites in the garden!

 

[rolfw]

Moving the LNB in and out will of course change the focal distance, it is important, but it is a case of trial and error, try and see which position obtains the best result.

 

[Channel Hopper]

Hi Martin

Dont worry about experience, we all start at the bottom

Offset dishes are a bit of an odd one, where the manufacturers rarely include the specific feehorn for optimum performance, and so you are left with the fitting of an aftermarket one, or use a combined LNB with integral feed.

The LNBs available provide a 'one size fits all' type feed where the focal dimensions are designed for quantity sales rather than quality results.

Ideally the best way to install is to have an analyser on the cable when checking for best performance (which is not just signal gain, but minimum unwanted noise)
If this is not an option then its worth finding the weakest satellite signal you can receive - in the UK on a 90cm you may find Sirius channels such as Single 24/7. Using this you can adjust the feed for both focal distance and skew, to bering the best out of the outdoor components

 

[martinw01908]

OK cheers guys I'll leave it loose in the middle and try adjusting it for best results later. I'll let you know how I'm getting on, great weather for it this weekend anyway.