LNB diameter?

nick6470

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#1
Hi All

Does the diameter of the lnb make a difference to reception? The reason i ask is because i had to replace my lnb for astra 19 (astra 28 is my prime focus) and there are now some channels that i cant receive as the signal quality is to weak and the new lnb has a smaller diameter than the old lnb. The problem is i dont know if these channels worked with the old lnb as it broke on the day of seting the thing up!

Thanks Nick
 

Channel Hopper

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#2
When you say diameter do you mean the feed cap ?

The design of the feed when integrated to the rest of the LNB chassis is a compromise between efficiency and cost.

The most efficient way is to have a feed designed specifically for the dish you are using, but this adds to the cost.

The distance fo feed to the dish will also have an impact on reception, as dies the skew or offset.

In general an LNB designed for an offset dish will not work well on a primfocus unit and vice versa

Take some pictures from front and side, someone here may be able to spot an obvious problem
 

nick6470

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#3
When i talk about the diameter of the lnb i do mean the white coloured thing that points at the dish. Unfortunatley i dont have a digital camera so i cant post any pics,sorry.

I have a triax 88 cm dish and i receive most channels from the astra 19 sat with good signal strength and quality, but the ones i dont receive all have the same frequency so i guess this is one of those 'beam' problems like i had when trying to receive itv and bbc (location is germany)?
 

rolfw

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#4
You may need to adjust the skew a little, the diameter of the cap should make no difference.
 

nick6470

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#5
Is it possible to some how 'kill' the lnb? The reason i ask is that i had reception from astra 19 using a digian receiver and then about an hour later all reception had gone even though i changed nothing on the dish\lnb, so i went and bought a new lnb installed it and it worked again and then after about a hour of viewing i switched off went out and when i returned and turned on the receiver, guess what..... 'no or a bad signal being received' on my tv screen. This is driving me f$§%ing crazy!!!!!
 

rolfw

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Berkshire
#6
Yes, you can kill an LNB, possibly by the receiver throwing out too high a voltage, but it isn't very common.
 

nick6470

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#7
Thanks rolf for your reply, that must be the problem i am having here. My sat installer is coming back on monday, is there a way that he can measure the voltage being thrown out by the receiver? So does that mean the receiver is defect? Does the company Digian make good receivers or should i insist on another brand?

Thanks again
 

rolfw

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My Location
Berkshire
#8
Don't know the receiver, but any volt meter will be able to measure the output and he will probably carry one. If the voltage is correct, then it can only be the cable, connectors or alignment, it is unlikely for two successive LNBs to be defective.
 
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