IF the twisted pairs are fed with differential drivers, then the noise
is "common mode" and cancels itself out. A simple TTL circuit over
twisted pair will still be quite vulnerable to RFI. Been there done
that for many, many, years in datacomm.
Jim, W4ATK
On 8/7/2014 10:22 PM, Jim Brown wrote:
On 8/7/2014 6:52 PM, [email protected] wrote:
Has anyone tried unshielded cable?; Cat 5E cable?;or whatever!
All of the unshielded CATx cables have very good immunity to external
RF and noise if each signaling circuit is carried by one of the
twisted pairs. The CATx cable carries RS232, which requires two pairs.
The two remaining pairs connect the key line and logic circuit (ACC2).
In general, a high quality twisted pair is far more important than a
cable shield ff the CATx cable is properly wired (that is, one pair
for each signalling circuit). The primary advantage of is higher CAT
spec is reduced crosstalk between pairs, which is a big deal for
Ethernet, but much less so for applications like this.
73, Jim K9YC
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