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["Capotosto, Michael" <capotosto AT bnl.gov>]

Gerard,

I spoke to the vendor today, he was surprised at the twist as well. He said he's going to cut the cables about a foot long, so he can strip back 6" extra on either end to ensure the pairs stay together, we have plenty that this shouldn't be an issue, even at production volume.

Best,

Michael Capotosto

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From: Gerard Visser <gvisser AT indiana.edu>
Sent: Friday, January 10, 2020 4:33:16 PM
To: Capotosto, Michael <capotosto AT bnl.gov>; Flemming Videbaek <videbaek AT rcf.rhic.bnl.gov>; Zhenyu Ye <yezhenyu2003 AT gmail.com>
Cc: Pak, Robert <pak AT bnl.gov>; star-fst-l AT lists.bnl.gov <star-fst-l AT lists.bnl.gov>; Scheetz, Robert <scheetz AT bnl.gov>; Camarda, Timothy <tcamarda AT bnl.gov>
Subject: Re: FST "Purple" Cable

 

hi Mike and all,
        I take it back. Apparently I really did not sacrifice a long enough piece this
morning. Now (after some off-list discussion) I much more carefully dissected a
longer piece of cable and things look fairly reasonable.
        I think the twist and lay of the pairs is kind of looser than I expected to see
but I really doubt that it will be any problem at all. We should proceed to use
this cable I think. In parallel, we should measure characteristic impedance and
reflections and crosstalk, but expecting decent answers on that so it should not
be allowed to hold up the T-board assembly and prototyping the FST. We'll just
get that done in parallel.
        This cable is really nice and flexible, and not too terribly fat. Robert you
will look into safety approval for it, right? Hopefully goes fine.
        Sorry for noise, I am glad this looks like not a problem after all.

                Gerard


On 1/10/2020 9:21 AM, Gerard Visser wrote:
> hi Mike,
>      Just got the cable sample from you -- thanks!
>      Looks pretty nice in genral, except the twisting of pairs is VERY loose,
> unexpected. I think we may need to look into this a bit. There are two possible
> issues:
>
> - The possible minor issue is that it may be very difficult to figure out what
> is what and keep the pairs reasonably together, when terminating this cable.
> (Send some to KC if they don't already have a piece. This is only a possible
> headache for assembly. The wire length outside the jacket should be pretty small
> (inch or two) and keeping the pairs together in that inch or two would be best
> but is not critical.
>
> - A possible major issue is if the pairs don't really lay as pairs in the length
> of the cable. [Dissecting a short piece it didn't look so good - but it is hard
> to really tell with a short piece.] Then there will be horrible crosstalk and
> reflections and we probably can't have that. We're going to have to bump up the
> priority of maklng some signal integrity / impedance measurement test on this
> cable. I had thought of that as something I would do because we should test it
> and know the right impedance value, but now it is more urgent we may have to
> decide go/no-go on this cable. Maybe you can try such a test too please? I am
> swamped here I will try something simple soon, but it may still take a bit.
>
>      Gerard
>
>
> On 1/7/2020 2:39 PM, Capotosto, Michael wrote:
>> Gerard, Flemming, Robert, and All,
>>
>> I’ve received the reel of cable yesterday, 1,100ft. I’ve opened up a short
>> piece, it appears to be correct. 36 conductors, plus a drain. We have an outer
>> foil shield with no braid.
>>
>> Please let me know what lengths you all need for testing, and where to send it
>> (and how urgently you need them shipped).
>>
>> The V3 T-Boards have been shipped FedEx overnight last night, but FedEx had a
>> delivery exception, it arrived late to the local hub. I should have it tonight
>> or tomorrow morning. I just need to put the Nicomatic connectors onto the
>> boards, I will be able to have them to our cable vendor by Thursday afternoon
>> so he can begin putting the D-Sub connectors on one end, and soldering the
>> opposite end to the T-Boards.