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LNB help / testing

p

Regular Member
Messages
112
Likes
0
My Satellite Setup
90cm gregorian
5way zone2
My Location
Rainham, essex
#1
Is there anyway to test an LNB with a meter whilst disconected from a satellite reciever.

The reason I'm asking is I get very low power on the Vertical reception,but my dish is perfectly aligned across the arc.

Also it is a c120 flange 0.7db universal, is there anything on the recivers setting that could have caused this.

Thanks for any help with this matter.
 
C

clarke belt

Guest
#2
An Lnb is basically a microwave receiver and dish feed and its IF output is fed at a much lower frequency along the coax cable to the main receiver.
In order to test the lnb without the dish you would need a 10 to 12 GHz signal generator feeding a resonant radiator in proximity to the feedhorn and these are very rare items and expensive.
You say it is a C120 flange Lnb and I wonder if it has a magnetic polariser between the Lnb and the feed horn if not its probably a 'Marconi' type 13/18 volts switching via the coax,and if so check if the voltage at the Lnb F plug changes when going from H to V.
If its the former look at the polariser menu to find the fine adjustment of skew and make sure this is not at one extreme which would still allow both polaritys but one much weaker than the other a situation which can't normally happen with the course H or V voltage switching where the isolation is very good.
Hope this helps clarke belt.
 
C

clarke belt

Guest
#3
Futher to my previous post there is of course the possibilty that the Lnb is faulty and I personally have had two Cambridge units that gave exactly the same symptoms as yours and nothing could be done cure them.
If after following my suggestions everything else in the receiver commands to the Lnb are normal then I think a new Lnb is required.
One final thing is have you just installed this setup or has it been working OK and the situation has developed.
If the former is the case then I have another possibilty but lets see how you go on with the info given so far.

clarke belt.
 

p

Regular Member
Messages
112
Likes
0
My Satellite Setup
90cm gregorian
5way zone2
My Location
Rainham, essex
#4
I've had it installed for nearly 2 years. Reading the fact that you'd had two lnbs, I thought i'd cut my loses and buy a replacement. Problem cured and working ok.

Thanks for the info.