Newsnet on Ka Band A

John

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You're right. But I have already bought LNbs from the Chinese that absolutely did not work properly. Unfortunately it is now the case that they recreate and copy everything. But often with very poor quality

Yep, true.
It really is a gamble.
 

scopus

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Llew

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The screenshots show the comparison between my Hughes Band A China-made LNB and my Norsat 9000A. Each has an FD1000 feedhorn installed, with optimum conditions set for each LNB on the dishes I use for recieving tne Newsnet frequency.

Checking 18556V, as shown, there is a slightly increased power level obtained with the Norsat compared with the Hughes, but obviously not enough for the LNB, which consistently fails to lock the frequency unless I'm very lucky over repeated tries.

The same observations apply with the occasional OB frequencies on the band. Maybe it's a problem with my particular Norsat specimen - does anyone else using a Norsat 9000A encounter a simiar anomaly on Newsnet?

Tests are on a Triax TD88, but I observe the same failure to lock on a Triax 1.1, with only a better chance of lock on the 1.2 Gibby. The Hughes invariably performs better on each dish, usually locking straight away.


Astra 1L V Hughes_4.JPG

Astra 1L V Norsat.JPG
 

dreamsat

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I already had such errors with bad distributors and DiSeqC switches. Some LNBs worked well and others didn't work at all. In my case it depended on the reinforcement. The distributor or the switch was always defective. Up to 3 dB loss or no Lock
I don't think that this good LNB is defective, although I've already had water damage on one of them.

best regards
 

John

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The screenshots show the comparison between my Hughes Band A China-made LNB and my Norsat 9000A. Each has an FD1000 feedhorn installed, with optimum conditions set for each LNB on the dishes I use for recieving tne Newsnet frequency.

Checking 18556V, as shown, there is a slightly increased power level obtained with the Norsat compared with the Hughes, but obviously not enough for the LNB, which consistently fails to lock the frequency unless I'm very lucky over repeated tries.

The same observations apply with the occasional OB frequencies on the band. Maybe it's a problem with my particular Norsat specimen - does anyone else using a Norsat 9000A encounter a simiar anomaly on Newsnet?

Tests are on a Triax TD88, but I observe the same failure to lock on a Triax 1.1, with only a better chance of lock on the 1.2 Gibby. The Hughes invariably performs better on each dish, usually locking straight away.


View attachment 136159

View attachment 136160



I don't have a Norsat Band A Llew but i have the same experience with an XMW Band D where it would find all the signals weak or strong but only lock certain ones. It could lock and open weak ones but just would not open stronger ones that were previously possible. I stopped using it in the end and just used the modded Gilat broadband rx boards on Ka A and Ka D which just seem to do the business without any problem.
 

Llew

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Gibertini 1.25m motorised dish driven by the AD3000, with either Inverto BU Quad or Norsat / XMW Ka LNBs . SMW 1.05m + 3 other dishes. Speccy: Promax HD Ranger+
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I already had such errors with bad distributors and DiSeqC switches. Some LNBs worked well and others didn't work at all. In my case it depended on the reinforcement. The distributor or the switch was always defective. Up to 3 dB loss or no Lock
I don't think that this good LNB is defective, although I've already had water damage on one of them.

best regards
Yes dreamsat, it's true that DiseqC or other switches will introduce loss, but in my tests each LNB has the same set-up from source, i.e receiver/DiseqC to LNB, yet I always get the same result, no lock with the Norsat.
However next time I shall try the same test with just the cable between.
Thanks.

I don't have a Norsat Band A Llew but i have the same experience with an XMW Band D where it would find all the signals weak or strong but only lock certain ones. It could lock and open weak ones but just would not open stronger ones that were previously possible. I stopped using it in the end and just used the modded Gilat broadband rx boards on Ka A and Ka D which just seem to do the business without any problem.
Yes John, the Norsat usually locks fine with the Horizontal horse racing feeds on the same Band A on Astra 1L, also the Turksat/ Hellasats when I tried them. It's just the Newsnet one that I have the problem. Thanks anyway, I'll stick with the Hughes for Newsnet.
 

John

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Ku - Ka -C & Ext C.
PC cards-TM5402 receivers.
Promax FSM.
My Location
North Nottinghamshire.
Yes dreamsat, it's true that DiseqC or other switches will introduce loss, but in my tests each LNB has the same set-up from source, i.e receiver/DiseqC to LNB, yet I always get the same result, no lock with the Norsat.
However next time I shall try the same test with just the cable between.
Thanks.


Yes John, the Norsat usually locks fine with the Horizontal horse racing feeds on the same Band A on Astra 1L, also the Turksat/ Hellasats when I tried them. It's just the Newsnet one that I have the problem. Thanks anyway, I'll stick with the Hughes for Newsnet.



Also Llew, i'm sure my downlink signals in Band A as well as Band D have reduced from about three to four months ago - i just don't seem to get the same levels as i did before.
 

s-band

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It may be related to higher phase noise on the Norsat. @John had a band A with water ingress on which the synth had been damaged. That was an extreme example as the phase noise was awful. The signal levels were fine but very little would demodulate. The narrower the signal, the more sensitive it will be to poor phase noise.

Here's an example where I was using an external reference with a Gilat but the reference phase noise was not fantastic. The phase noise increases with frequency multiplication by 20 log10 (N) dB where N is multiplication factor. I changed the divider to increase the ref frequency and reduce the multiplication (from 64 to 16) and improved it significantly.

The CS plots show the effect of the higher phase noise spreading the constellation. You need a strong, low symbol rate, signal to check in this way.

Of course, your problem may be something completely different!
 

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Llew

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My Satellite Setup
Triple Dragon, Dreambox 8000, Echostar AD3000ip, TBS6522,6925,6983 PCie cards.
Gibertini 1.25m motorised dish driven by the AD3000, with either Inverto BU Quad or Norsat / XMW Ka LNBs . SMW 1.05m + 3 other dishes. Speccy: Promax HD Ranger+
My Location
The Flatlands of East Anglia
It may be related to higher phase noise on the Norsat. @John had a band A with water ingress on which the synth had been damaged. That was an extreme example as the phase noise was awful. The signal levels were fine but very little would demodulate. The narrower the signal, the more sensitive it will be to poor phase noise.

Here's an example where I was using an external reference with a Gilat but the reference phase noise was not fantastic. The phase noise increases with frequency multiplication by 20 log10 (N) dB where N is multiplication factor. I changed the divider to increase the ref frequency and reduce the multiplication (from 64 to 16) and improved it significantly.

The CS plots show the effect of the higher phase noise spreading the constellation. You need a strong, low symbol rate, signal to check in this way.

Of course, your problem may be something completely different!
That's very informative s-band. When (if) I do lock the TP with the Norsat, I'll check the plot result for possible noise discrepancies.
 

s-band

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That's very informative s-band. When (if) I do lock the TP with the Norsat, I'll check the plot result for possible noise discrepancies.
You're welcome. I found a plot from John's wet LNB on UnireSat
 

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