LNB Feedhorn probs on Nilesat

P

pocster2

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My Satellite Setup
Humax CI-5100, 80cm 19.2e/13e/7e, 100cm 1w, 150cm 7w, 240cm on order.
My Location
Northwest UK
#1
I have recently got a used 1.6 metre dish to go with my Humax receiver and am trying to get reception of Nilesat 7w. I am based near Manchester (53 N, 2 W). Having searched these forums, I see that there are several members receiving the vertical transponders (the horizontal ones seem pretty impossible in the UK) on 1.2 metre dishes. The reception on my 1.6m is very poor. The education channels are the only ones I can receive with any regularity. Last weekend I managed a couple of other transponders with blocking and intermittent signal.

I have peaked every setting. The dish is as perfectly aligned as I can get it and I have adjusted the Skew and focus of the feedhorn. I am now turning my attention to the feed/lnb.

The current setup is a Cambridge Ae33 0.7dB C120 coupled to a Cambridge feedhorn. I know that the LNB isnt the best in the world and am considering an Invocom 0.3dB. Also, the feedhorn has a little corrosion (oxidisation) on the surface of the scalar rings.

Will the oxidisation affect the performance of the feed to any extent? If I replace the feed/LNB, am I better with a C120 setup or a combined LNB/Feed? I have read that combined LNB/feedhorns don't really work so good on big dishes.

Finally, I will have the opportunity to try out a 2.4 metre dish in the next couple of weeks. Does anyone think it is likely that it will pull in any of the Horizontal transponders?

Many thanks in advance for any help you may give. It has been 10 years since I last messed about with satellites and this forum has really helped me bring myself up to speed.
 
A

asharif

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#2
Hi
The oxidization of external surface of feedhorn has no effect on signal reciption , the internal surface should be smooth and shiny.
I would recommend a low noise LNB min .4 db noise figure , .3 would be much better , good luck
 
Lancelot

Lancelot

Retired Mod
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My Satellite Setup
SS1.
125cm Gibbi with Channelmaster feedhorn and Inverto C120 twin.
36v H to H 62E - 61.5W
My Location
South central
#3
You may want to find out the make of dish. and see what the manufacturer recommends as a feed for it as there are very variable results to be had with differing feedhorns.

As far as I can tell you should be getting a little more than that with a 160cm antenna in your location as I am currently getting about 50 or so chnls from that location with my kit down here.


L.
 
O

Old Satellite

Specialist Contributor
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#4
The Vertical transponders are approx 10-15 % higher in the peak reception at towards the extent of the footprint.

My own 1.8 mtr prime focus dish however in a Mid East UK location recieves all transponders with around 55-85%. so your dish should be perfoming a little better than it appears.

Several transponders mostly vertical are recieved on a good 1.2 mtr are reported in the UK at several locations.

What type of feedhorn do you have fitted? how old is your dish and what make is it?


Mostly a C120 based dedicated feedhorn will work better than a normal universal type LNB and feed.The universal feedhorn are not designed or matched (feedhorn) for the size of dish you currently have.

regards

Oldsat
 
P

pocster2

Member
Messages
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My Satellite Setup
Humax CI-5100, 80cm 19.2e/13e/7e, 100cm 1w, 150cm 7w, 240cm on order.
My Location
Northwest UK
#5
Thanks Oldsat,

The dish is something I picked up second hand off ebay a couple of months ago. It's a 1.5m fibreglass prime focus. I am guessing it is fairly old as it came with a connexions motor and positioner (really aincient, east and west buttons, 16 sat positions settable by trimmer potentiometers).

The LNB and feedhorn are branded Cambridge. They are C120, the LNB as mentioned is marked 0.7dB. I am assuming they are not the original LNB/feed as there was a cable that would have controlled a mechanical polariser which had been cut off but was still cable tied to the feed support arms.

The feed support arms were very rusty and fragile when I aquired the dish and I have made some new ones with copper pipe. I have been very careful to ensure that they were of identical length to the originals and have spent a fair bit of time getting the focal position to the optimum (using 1 deg W satellite).

I will have a 2.4M fortec star to play with hopefully later this week. I had expected some better results on the vertical transponders with the current set up as I was optomistic about the 1.2m reports you mentioned.

regards, Paul
 
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