Advice needed on multiswitch

Dippy

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I have been trying to diagnose my problem and am close to buying a new multiswitch, but would appreciate opinions to give me confidence that its the right solution.

My original setup was an 80cm dish with quattro LNB to an Antiference AMS716T multiswitch. I only have two TVs connected, so this is really just for the future if/when bedroom TVs get upgraded. One TV had fine Freesat reception but the other had occasional data loss resulting in momentary corruption of part of the picture. However due to trees eventually the signal degraded and I was forced to get the dish relocated, and it had to be up on the roof. The guy who did it preferred to change to a perforated Sky dish to avoid wind problems, and assured me this was fine as the signal was strong. He had to change to a quad LNB. This seemed OK for a while until that 2nd TV again started getting occasional glitches, but also so did the 1st TV on certain channels, but not as bad as the 2nd TV.

Assuming this was still a tree problem, I got the guy back to raise the dish but he assured me the signal was still good. So he did some measurements on the multiswitch and then direct to the LNB and concluded that the multiswitch outputs were saturated. He saw that the gains were on max (my fault) and so turned them down. However this did not solve the problem, as there was still occasional picture corruption on TV 2. So he connected the cables to both TVs direct to two of the cables from the quad LNB. This seemed to improve the situation. Over the next few weeks we did not experience a single picture corruption on either TV.

However I still want to have a proper solution, and it bugs me that the multiswitch should work, because that's its purpose. So I have done some experimentation:
- Using different outputs does not change the situation
- Using 6dB attenuators at the LNB inputs appeared to improve the situation, but caused total loss of C5HD
- Using 3dB attenuators at the LNB inputs appeared to improve the situation without loss of any channel, but there is still occasional picture corruption on the 2nd TV

I find it interesting that the problem is more common with TV 2 than TV 1. The problem is still rare - I might notice it once a week on TV 1, and we could watch TV 2 for hours with no problem and then there would be several cases of picture corruption within a few minutes, then it would be fine again for a while. But with the LNB outputs cabled directly to the TVs there is never a problem (the cable is Labgear PF100 and there are no long runs). So although I'm still dubious about it, the only conclusion I can draw is that the multiswitch itself is responsible for the signal corruption.

Opinions very welcome. If I replace the multiswitch then I don't see that I would be wise to replace it with another Antiference. Can anyone advise which other brands should be good?
 
What's the idea of having a multiswitch with a quad LNB?
 
Why bother with a multiswitch? An octo lnb would give you 4 extra lnb outputs for the bedroom TVs. It would also remove the inherent signal loss in using a mutiswitch.

BTW your installer was talking utter BS about wind loading being reduced with perforated Sky dishes - the holes are too small to have any effect on wind loading
 
I have been trying to diagnose my problem and am close to buying a new multiswitch, but would appreciate opinions to give me confidence that its the right solution.

My original setup was an 80cm dish with quattro LNB to an Antiference AMS716T multiswitch. I only have two TVs connected, so this is really just for the future if/when bedroom TVs get upgraded. One TV had fine Freesat reception but the other had occasional data loss resulting in momentary corruption of part of the picture. However due to trees eventually the signal degraded and I was forced to get the dish relocated, and it had to be up on the roof. The guy who did it preferred to change to a perforated Sky dish to avoid wind problems, and assured me this was fine as the signal was strong. He had to change to a quad LNB. This seemed OK for a while until that 2nd TV again started getting occasional glitches, but also so did the 1st TV on certain channels, but not as bad as the 2nd TV.

Assuming this was still a tree problem, I got the guy back to raise the dish but he assured me the signal was still good. So he did some measurements on the multiswitch and then direct to the LNB and concluded that the multiswitch outputs were saturated. He saw that the gains were on max (my fault) and so turned them down. However this did not solve the problem, as there was still occasional picture corruption on TV 2. So he connected the cables to both TVs direct to two of the cables from the quad LNB. This seemed to improve the situation. Over the next few weeks we did not experience a single picture corruption on either TV.

However I still want to have a proper solution, and it bugs me that the multiswitch should work, because that's its purpose. So I have done some experimentation:
- Using different outputs does not change the situation
- Using 6dB attenuators at the LNB inputs appeared to improve the situation, but caused total loss of C5HD
- Using 3dB attenuators at the LNB inputs appeared to improve the situation without loss of any channel, but there is still occasional picture corruption on the 2nd TV

I find it interesting that the problem is more common with TV 2 than TV 1. The problem is still rare - I might notice it once a week on TV 1, and we could watch TV 2 for hours with no problem and then there would be several cases of picture corruption within a few minutes, then it would be fine again for a while. But with the LNB outputs cabled directly to the TVs there is never a problem (the cable is Labgear PF100 and there are no long runs). So although I'm still dubious about it, the only conclusion I can draw is that the multiswitch itself is responsible for the signal corruption.

Opinions very welcome. If I replace the multiswitch then I don't see that I would be wise to replace it with another Antiference. Can anyone advise which other brands should be good?


You could have a faulty Multiswitch, Antiference are a well respected company though so don't let that put you off.

You could have an electrical fault, maybe off the 2nd tv or something [anything] connected to it or tv1 or in anyway connected & tracks through & upsets the multiswutch & more than if directly wired to the quad.

Could be a subtle cabling/ connector issue - check all the cables & connectors including too sharp bends/ kinks & stray copper strands in a connector- Labgear are not known for the highest quality btw -

Could be local interference, it should show up on direct cabling to the quad, except MS's are a % more susceptible to noise, the way they work generally introduces more noise so any extra can impact more

Still not cleaning the tree/s

Not sure about ditching the 80 & quattro lnb because of wind loading & swapping to a quad - the reasoning's right.. but 80cm is not that big, I fit loads of larger dishes in some of the highest & most exposed locations. Zone 2 sky dishes are not a bad choice though & they are also a lower profile being horizontally oval, as Dave said though, the holes don't really make a difference over certain wind speeds. Quads [on mulitswitches] are more susceptible to have issues too
 

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