C band feedhorn/LNB/LNBF suggestion

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emuman100

emuman100

Thread Starter
SatelliteGuys Pro
Dec 15, 2007
247
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Pennsylvania
Hello,

I'm having issues with my c band reception. I have a Fortec Star 180cm prime focus dish with BSC621 LNBF. All I really want is DW-TV and Deutsche Welle Radio from AMC1. I aligned it with a linear Ku band LNBF from Sadoun, the KUL1. Yesterday, I installed the BSC621 and locked it in as strong as I could get it, with about 50% signal quality on 3740MHz trying to get DW-TV nice and strong. This afternoon, reception was just lost, which I believe to be the clouds, as there are stratus clouds over my area that brought rain. I went outside and after a few hours, got a signal back, but DW-TV still pixelates and DW Radio cuts out, whith about 45 to 50% signal level. I believe the the change in clouds/weather was the cause. There were still stratus clouds over the sky, but maybe they weren't as thick or dense. There are trees, which may be blocking the signal, but they seem to be well out of the way. Also, the scalar ring has a nickel sized chunk missing from the outer ring of the scalar ring. I'm not sure if it's the weather, the trees, or the scalar ring/LNBF, but something is wrong. The 22kHz switch in the LNBF doesn't seem to work properly, as when I would go from C band to Ku, to C again, I would hear a squeal from the LNBF actually (yes, strange, isn't it?) and my C reception would go dead. So, despite my current problems, I'm going to get a new LNBF or LNB and feedhorn.

Since I just want C band, I was thinking of getting the Chaparral Micropak 3G C band LNBF, or a single polarity feed horn from Chaparral and a LNB, hopefully Norsat or Cal Amp if I could find it. Would there be any benefit in performance with a Micropak 3G than with a seperate feed horn and LNB? I know Chaporral makes good stuff, but I mainly want one polarity and one frequency, as a seperate feed horn and LNB will be pricey. And how would you adjust skew on a single output single polarity Chaparral feedhorn without a servo?

Thanks.

Jonathan
 
truckracer

truckracer

SatelliteGuys Pro
Sep 17, 2004
4,338
351
Charleston wv
My experience one time.

When I first got my 7.5' mesh SAMI c-band dish I had a dms international c-band only lnbf.
Every time it got cloudy outside I would lose vertical polarity. I thought the lnbf was failing or had a coax problem. I checked the lnbf voltage at the dish and all checked out good. I started tuning the focal distance and the focal point and got a much better signal. I never lost vertical again in the clouds.

Check your focal distance and focal point.

It could possibly be the 6 foot dish since its beamwidth is almost 3 degrees. This means that when you are focused on amc-1 you are also seeing part of amc-18 and amc-4.
That means you are suseptable to digital interference from the neighboring satellites. This could explain the sudden drop out in signal. If one of the neighboring satellites turns on a transponder that is near the same downlink frequency and polarity you could have digital drop out.

Check all the obvious stuff first like your coax connections and try resetting your receiver (power it down with the power switch or just pull the plug for a few seconds). Sometimes a quick re-boot does wonders.

You may try re aligning your dish for the very best signal. A lot of times the smaller dishes for c-band (smaller than 8 feet) have to be precisely tuned to get a good digital lock.
We had a guy on the forum a while back that could lock G-15 transponder 3 to get the channel maps for his 4dtv box with a 5 foot mesh. Wow.

Good luck. When the signal pixalates or macroblocks look at the signal quality meter and see what it is doing. If it is bopping up and down really quick that could be adjacent satellite interference or terrestrial interference from some microwave source in your neighborhood.
 
emuman100

emuman100

Thread Starter
SatelliteGuys Pro
Dec 15, 2007
247
0
Pennsylvania
truckracer,

After reading your reply I went out and checked the focus. For my dish it's 682cm, and it was spot on. I actually could not get a decent signal at all if I was out of the focal point. So, by adjusting the feedhorn of the BSC621 I got within the focal point.

Here is how I aligned the dish. I took a ku LNBF and aligned it and tuned it for the highest signal quality on the Pentagon channel on AMC1. I then changed to the BSC621 later that week. Should I assume that since I peaked it for the strongest ku signal quality I could get, that it is peaked for azimuth and elevation on c band? Since my dish is 6' and might have a narrow beamwidth, but I still got a strong signal on ku, would it be strong on c band or do I have to peak it again? My cables and everything are ok, I made sure they worked properly. Also, as far as I am aware, no terrestrial signals interfere with it. The signal quality bobs up and down between 45 and 50 percent. Think there is any interference?

That surprises me that on a 5' mesh he got a stable lock. Think I might need to adjust azimuth and elevation?

Thanks.

Jonathan
 
emuman100

emuman100

Thread Starter
SatelliteGuys Pro
Dec 15, 2007
247
0
Pennsylvania
gabshere,

I adjusted the skew and focal depth for the strongest signal quality I can get. I'm going to try to peak the azimuth and elevation on c band to see if I can get a better signal quality. In the meantime, I purchased a Norsat 8530 LNB and a Chaparral dual output feedhorn for vertical and horizontal polarities on c band. I also purchased a cheap LNB for the horizontal output to cover it, since I really want vertical for DW-TV. If aligned properly, will the Chaparral feedhorn and the Norsat 8530 LNB gove me better reliability than the BSC621?

Thanks.

Jonathan
 
truckracer

truckracer

SatelliteGuys Pro
Sep 17, 2004
4,338
351
Charleston wv
It looks like that 3740 transponder is using a 7/8 forward error correction ratio. That is going to be hard to get with a 6 foot dish I think. It will have to be perfectly tuned. That tight ratio FEC means that most of the bandwidth is video/audio transmission and very little used to correct errors. The 6 footer will see noise from the neighboring sats.
 
emuman100

emuman100

Thread Starter
SatelliteGuys Pro
Dec 15, 2007
247
0
Pennsylvania
I think I got it so it's properly aligned. I installed the new feedhorn and LNB and having more signal problems. I got a Chaparral Dual-Feed feedhorn and a Norsat 8530 LNB. Are there any incompatibilities with that combination that I missed? I could tune the old BSC621 to where I'd get almost perfect signal with no blocking at all, most if not all the time. With this I cannot. I got a BSC211 to fill the other output, also. That receives the horizontal signal. I can scan in everything on Lyngsat except the Ion multiplex. Is it still there?

I'm going to cut and trim some trees as well and see if that fixes things.

Thanks.

Jonathan
 
A

ausente

New Member
Feb 25, 2008
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0
anyone know if I can catch NSS806 with 10 ft mech Cband dish at london ontario canada...I tried 2 times but no singnal ..need diferente LNB or feedhorm..thanks guys...
 
Larry1

Larry1

SatelliteGuys Pro
Aug 24, 2005
1,594
138
Port Hope, ON Canada
Just a thought, how are you powering the Norsat? Will your reciever power anything but a voltage switched LNBF? I don't know, but others here should.

There was some posts here about using a straw to make an inclinometer to check your line of sight. Then you can check to see if those trees are a factor or not.
 
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