[TowerTalk] metal-on-metal interference

Pete Smith n4zr at contesting.com
Sat Jul 24 04:25:05 PDT 2010


For sure - I had terrible line noise a few years ago that was traced to 
a lightning arrestor on top of a nearby pole.  Seems a woodpecker had 
undermined one of the two lag bolts - it had come loose and was just 
sitting in the hole in the pole and the arrestor bracket.  The lineman 
who fixed it (by removing the loose bolt) told me that the field 
gradient near the 7500 volt line was enough to cause sparking between 
the bracket and the loose bolt,l and that his company now used a 1-bolt 
bracket to avoid this problem - I guess they would rather have the 
arrestor fall of altogether, rather than deal with RFI complaints.

73, Pete N4ZR

The World Contest Station Database, updated daily at www.conteststations.com
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On 7/23/2010 7:02 PM, K1TTT wrote:
> No, metal on metal rubbing by itself doesn't cause interference.  But if
> there is a voltage difference between the parts that are rubbing THAT can
> cause interference.
>
>
> David Robbins K1TTT
> e-mail: mailto:k1ttt at arrl.net
> web: http://www.k1ttt.net
> AR-Cluster node: 145.69MHz or telnet://dxc.k1ttt.net
>
>
>    
>> -----Original Message-----
>> From: Michael Fox - N6MEF [mailto:n6mef at mefox.org]
>> Sent: Friday, July 23, 2010 22:03
>> To: towertalk at contesting.com
>> Subject: [TowerTalk] metal-on-metal interference
>>
>> I've heard that metal-on-metal rubbing contact causes RFI.  But doing some
>> Google searches, I can't find a source of information.
>>
>>
>>
>> Can someone tell me:
>>
>> 1)  Is this true?
>>
>> 2)  If so, is there a source for information?
>>
>> 3)  Specifically, is there a general frequency range for the interference?
>>
>>
>>
>> Thanks much,
>>
>> Michael
>>
>> N6MEF
>>
>>
>>
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>
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