Smart video hub 40x40 loosing signal

So I have just built a mobile studio, using the new ATEM TV studio 4K, with the smart videohub 40x40 with hyperdeck mini’s for recording each camera separately. I have the BM studio cameras routed through the videohub, then routed to the hyperdecks and the ATEM switcher. The cables I am using are 50M SDI Belden 1855A.
The cameras are set to 4K25p, so 6G. The pictures flicker intermittently when on these cables, but don’t on shorter cables. . So I assumed that there was a problem with the cables, and there still maybe however The 1855A cables should do to 63m, apparently.
However, when I connect the cameras directly to the ATEM, I get a stable picture, no issues. The only problem, is I can’t record each camera separately.
So is my Videohub faulty, or is it down to the cables? Is there an alternative way to record to the hyperdecks without going through the hub?
Thanks.

that's kind of a long run for 1855a, esp with 6G-sdi. at 100ft, the posted loss for 6G is 28db of signal-quite a lot.

I'd try using 1505a (-21@100ft) or better yet 1694a (-17@100ft) cable. you can see they both have better loss specs for 6G

Thanks for the reply. According to the specs, the max that the cable should send is 62m. At 50m one piece of equipment works flawlessly, but the other does not. I’ve also manage to send 4k25p from my BM Production cam 4K over 100m using normal satellite cable (75ohm) terminated with BNC connectors. Which is what I can’t understand why they won’t work with the VideoHub.
I can try the other cables, but I have to get them made up and sent to me, which takes a few days (where I am) and I’m afraid that they also won’t work, leaving me way behind in my business launch!


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You know that what Belden and other cable manufacturers give on length are tested under ideal circumstances.. With a connector that also matches for 6G or higher. (Yes you also need higher standard connectors.. The default connectors we used in the 1,5G world have a different di-electrum which causes a lot of dampening above 4,5Ghz.

Also 62 meters under perfect circumstance.. So without ANY other cable or interference nearby the cable. No power cabling, no other video cables.. No magnetics fields or power supplies near by.. Just 1 cable in lab conditions.

Our thumb rule is cut the specified length by the manufacturer in half. That is the maximum length safe to go for on the road, rental conditions and racking conditions.
Not to say that inputs of Atems and videohubs also have some trouble to recover from the length the cable manufacturer gives.. So Belden can say there cable does 62M on 6G. But that doesn't say it will do that with every device manufacturer.. As Macom, Semtech, Texas Instruments (the 3 leading chip manufacturers in 3,6,12G chipsets) all have different specs for there chips..

Go with a better cable, and appropiate connector that will handle 6/12G sdi.

buy a crimper, some connectors, and the right cable. not that expensive, and fairly easy to learn to do it. save yourself a TON of cable grief. and give up the satellite cable, it's just not designed for SDI signal...wonder it worked at all.