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Re: [RFI] Ethernet Extenders

To: "'Jim Brown'" <jim@audiosystemsgroup.com>,"'RFI List'" <rfi@contesting.com>
Subject: Re: [RFI] Ethernet Extenders
From: "David Jordan" <wa3gin@comcast.net>
Date: Mon, 25 Jun 2007 12:50:28 -0400
List-post: <mailto:rfi@contesting.com>
Tests were done with 5 watts into a dummy load.  There is no problem in SSB
even at 1500 watts to 1/2 wave antenna.  

The problem appears to be something flaky in the actual command data stream.
Since I'm using encrypted tunneling I can't really sniff the data
transmissions but I'm working on removing the encryption. I have installed
Telco Grade line filters (K-COM, 2 in series) on the CAT 5 lead to the
Ethernet boxes. The power supply line(s) is also configured as described
below, with toroidal filters (multiple) at both ends of the connection.  

The CAT is buried and it is shielded like heliax. The shield is grounded at
both ends. The barn has a ten point UFER ground (8ft ground rods), the house
has two 8ft ground rods. 

I think more and more that this is an RFI problem but wanted to here from
folks on this reflector.  

Seems if I had any RFI the little Ethernet boxes would jump up and down when
I run 1500 SSB.  The connection lock-ups only occurs when a specific command
string is send from the remote PC to the host PC.  That Kenwood command
string, inside the encrypted pipe simple tells the TS-480 to go into "send"
mode. The failure only occurs while the radio is in CW or AM mode. 

This weekend I'll attempt to remove the encryption and try to sniff the data
stream. 

I really appreciate all the thoughtful suggestions.

Dave
Wa3gin 

-----Original Message-----
From: rfi-bounces@contesting.com [mailto:rfi-bounces@contesting.com] On
Behalf Of Jim Brown
Sent: Monday, June 25, 2007 12:17 PM
To: RFI List
Subject: Re: [RFI] Ethernet Extenders

On Mon, 25 Jun 2007 11:03:48 -0400, Martin AA6E wrote:

>However, you might want to seriously look at 
>your system grounding. 

The problem is only on 40M and 30M. 

This tells us that it is NOT a grounding problem, nor is it 
related to noise or the grounding between buildings. The most 
likely cause is that some wiring is acting as antenna and picking 
up HIS transmitter. The obvious culprits are the 1,000 ft wire and 
the power supply at either end. I also wouldnt rule out the 
cables connecting the extender to his rig, other networking box, 
etc. 

The first thing I would try is 7-9 turns of that cable at the ham 
shack end around a #43 or #31 2.4 inch toroid (FT-240). If that 
doesnt fix it, add one around the power supply on the ham shack 
end. If you still have problems, add chokes to those other cables 
in the shack, and finally at the house. 

These chokes will also suppress any common mode noise radiated by 
these cables that you may be hearing on the HF bands. Ordinary 
10BaseT Ethernet traffic, usually produces birdies on 30M, 20M, 
15M, 10M, and 6M. 100MB Ethernet equipment is multi-mode -- that 
is, it carries both 10MB and 100MB traffic, and most modems work 
at 10MB on their Ethernet port. 

For more detailed advice, see

http://audiosystemsgroup.com/RFI-Ham.pdf

73,

Jim Brown K9YC


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