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On 11-Jan-2000 James Manning wrote:
> [ Tuesday, January 11, 2000 ] Andy Poling wrote:
>> On Tue, 11 Jan 2000, Gregory Leblanc wrote:
>> > If you cut the cable
>> > lengthwise (no, don't cut the wires) between wires (don't break the
>> > insulation on the wires themselves, just the connecting plastic) you can
>> > get your cables to be 1/4 the normal width (up until you get to the
>> > connector).
>>
>> I don't know about IDE, but I'm pretty sure that's a big no-no for SCSI
>> cables. The alternating conductors in the ribbon cable are sig, gnd, sig,
>> gnd, sig, etc. And it's electrically important (for proper impedance and
>> noise and cross-talk rejection) that they stay that way.
>>
>> I think the same is probably true for the schmancy UDMA66 cables too...
>
> So just check with a cable spec and make sure you're not separating a
> data signal from its ground return path. Throw some mag rings around
> the thing if you want, but since we're (hopefully) terminated properly
> (no reflection) the crosstalk issues aren't huge... they suffer more
> through the LC matrix of connector adaptors than this split would cause :)
>
> James
> --
> Miscellaneous Engineer --- IBM Netfinity Performance Development
Have a look at old 3M cables (used in most old suns and all old decstations).
They have all the wires separated. And they work at least up to SCSI2. I
also thought that the sig/gnd/sig/gnd was mandatory but these cables prove that
there is another way to do it at least in some cases.
My $0.02
- ----------------------------------
Anton R. Ivanov
IP Engineer Level3 Communications
RIPE: ARI2-RIPE E-Mail: Anton Ivanov <[EMAIL PROTECTED]>
@*** Segal's Law ***
A man with one watch knows what time it is;
a man with two watches is never sure.
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