On Mon,3/7/2016 11:07 AM, Clay Autery wrote:
I'm not sure what the RFI issue would be that would require CAT 7... Tell me what you're trying to fix and I can offer more info...
There are well known issues with equipment using one of the wired Ethernet standard rates (have forgotten which one) generating carriers at several frequencies in the HF bands and on 6M. I'm primarily a CW guy, so the ones I run into are around 14030, 21052, the low end of 10M, the low end of 6M, and a couple of frequencies on 30M. These signals are radiated as a common mode signal, and I've been told that properly terminated shielded CAT5/6/7 eliminates it. Properly terminated means both in the cable-mounted plug and the equipment-mounted jack. I've also experienced broadband hash on 2M with a talkie within a foot or two of unshielded CAT5/6, including Belden's excellent Mediatwist cable.
In addition to its use for wired Ethernet, unshielded CAT5/6/7 is quite useful in noise sensitive circuits because of its high twist ratio. As with Ethernet, twisted pairs reject noise and crosstalk ONLY when wired with one pair per circuit -- that is, or and or/blk as a circuit, bn and bn/blk as a circuit, and so on.
73, Jim K9YC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
