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Re: [TowerTalk] OT: Exterior Ethernet Cable

To: "Tower Talk List" <>
Subject: Re: [TowerTalk] OT: Exterior Ethernet Cable
From: "Jim Brown" <>
Date: Tue, 12 Aug 2008 00:59:01 -0700
List-post: <">>
Roger said:

>> In the shop the computers are setting within 2 to 3' of 
>> the rigs, which run the legal limit. 

I replied:

> Doesn't matter. Virtually all rigs are shielded, and SHIELDED 

>But again I was pointing out that 
>being close to RF normally has little effect.

Being close to a rig does NOT make you close to RF. RF field strength 
is generated by RF current flowing in an unshielded wire. It does not 
leak out of a well shielded box (or at least very little). The RF is 
out surrounding the antenna, not next to the rig. 

A ham shack is hot with RF only when RF current is flowing through the 
shack -- for example, when common mode current is flowing on the 
transmission line. I had a lot of RF in my shack in Chicago when I 
loaded a long wire (on 80 and 160) that ended at the antenna tuner in 
my shack, or a 30M vertical that was 10 ft away out the window. The 
shack was hot with RF because it was close to the antenna, not close to 
the transmitter. 


Jim K9YC


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