Re: Min Distance from VHF Antenna in Wireless Service Providers http://www.dslreports.com/forum/r17271915 en Fri, 27 Nov 2009 16:53:16 EDT Fri, 27 Nov 2009 16:53:16 EDT Re: Min Distance from VHF Antenna http://www.dslreports.com/forum/remark,17271915 lutful : Here are various Ethernet baseband spectrum. Properly twisted CAT5 cable has 50-100dB VHF rejection.
]]> http://www.dslreports.com/forum/remark,17271915 Tue, 14 Nov 2006 01:50:54 EDT Re: Min Distance from VHF Antenna http://www.dslreports.com/forum/remark,17271691 sporkme :
said by lutful See Profile :

said by sporkme See Profile :

Curious, what's the spectrum that ethernet uses (100MB FE)?
Fast Ethernet transmission uses 125Mbps "raw" data rate which is carried in a 62.5Mhz "MLT-3" waveform.
So you're saying that ethernet is centered at 62.5 MHz or goes from "0"-62.5MHz?
said by lutful See Profile :

There is not much VHF coming out of properly twisted portions of the cable - most noise is coupled in the small untwisted section near the connectors.
I was thinking more about RF from other sources getting into the ethernet cable and providing a hard to diagnose failure or near-failure.

So anything with a strong harmonic that lands somewhere below 100MHz could be bad news, right? Technically, ethernet is RF, correct?]]> http://www.dslreports.com/forum/remark,17271691 Tue, 14 Nov 2006 00:28:36 EDT Re: Min Distance from VHF Antenna http://www.dslreports.com/forum/remark,17270760 wispman : One time I had an ethernet cable I put in at an install that ran across a desk and it went right by a police scanner. The scanner "keyed up" and was locked on something like 150-160mhz.]]> http://www.dslreports.com/forum/remark,17270760 Mon, 13 Nov 2006 21:46:23 EDT Re: Min Distance from VHF Antenna http://www.dslreports.com/forum/remark,17265924 lutful :
said by sporkme See Profile :

Curious, what's the spectrum that ethernet uses (100MB FE)?
Fast Ethernet transmission uses 125Mbps "raw" data rate which is carried in a 62.5Mhz "MLT-3" waveform.

There is not much VHF coming out of properly twisted portions of the cable - most noise is coupled in the small untwisted section near the connectors.]]> http://www.dslreports.com/forum/remark,17265924 Mon, 13 Nov 2006 02:42:42 EDT Re: Min Distance from VHF Antenna http://www.dslreports.com/forum/remark,17265878 AMD Phreak : I think isnt it like 100MHz?

Personally I dont chance it. I use STP for all tower installs due to the fact of there is so much RF where our gear is.

The big sticks are hard to get away from. You just have to do your best. I can check with the RF engineer and see what he thinks, in the AM. It shouldnt be all too bad though. I have put some 4.9GHz equipment next (4' above) to a high power 900MHz transmitter (500 or some watts) and didnt have a problem
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said by AMD Phreak See Profile :

Go as far as you can, but more importantly run STP to the radios, that is if they are on the tower.
Curious, what's the spectrum that ethernet uses (100MB FE)? Any harmonics from nearby transmitters to look out for (meaning, do any "common" VHF bands perhaps disrupt ethernet with one of their harmonics)?]]> http://www.dslreports.com/forum/remark,17265802 Mon, 13 Nov 2006 01:31:19 EDT Re: Min Distance from VHF Antenna http://www.dslreports.com/forum/remark,17265654 keefe007 : How close have you mounted to VHF? The problem is that this antenna is near 15/20 feet tall so it's hard to avoid. It is one of those whip antennas with little ears hanging off. I would be mounting 3 120 degree 2.4 sector antennas on a pole roughly 1.5 feet horizontally away from it.]]> http://www.dslreports.com/forum/remark,17265654 Mon, 13 Nov 2006 00:41:37 EDT Re: Min Distance from VHF Antenna http://www.dslreports.com/forum/remark,17265323 AMD Phreak : Go as far as you can, but more importantly run STP to the radios, that is if they are on the tower. Overall, it shouldnt be affected, I have experience with stuff being next to VHF, UHF, and high-power 900MHz paging and have not had any issues.]]> http://www.dslreports.com/forum/remark,17265323 Sun, 12 Nov 2006 23:29:05 EDT Min Distance from VHF Antenna http://www.dslreports.com/forum/remark,17264785 keefe007 : What's the minimum separation I should have between a 2.4 cluster and a 150 Mhz VHF antenna? Can they be in the same plane?]]> http://www.dslreports.com/forum/remark,17264785 Sun, 12 Nov 2006 21:58:59 EDT