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Re: [RFI] EMI Tape?

To: Rfi List <RFI@contesting.com>, KD7JYK DM09 <kd7jyk@earthlink.net>
Subject: Re: [RFI] EMI Tape?
From: James Gordon Beattie Jr <w2ttt@att.net>
Date: Wed, 16 Jun 2021 07:40:01 +0000
List-post: <mailto:rfi@contesting.com>
Kurt,
It is used in the cellular industry to cover bi-metal junctions that are 
sources of near field Passive Inter-Modulation (PIM).  The tape blocks the RF 
sources from mixing at these points and prevents the generation of additional 
interfering signals at frequencies used by receivers at a site.

In other cases, the RF sources involved are simple harmonics from high power FM 
transmitters.  For example, a 101.1 MHz transmitter can produce a strong 7th 
harmonic on 707.7 MHz which is in the middle of a cellular uplink passband. 
Interference there can crowd out weak cell phone signals.  I've seen cases 
where the spectral purity from the FM broadcaster's antenna is fine, but a 
poorly designed, or missing cover on the transmitter itself is allowing for 
unfiltered RF harmonics to be emitted.  Tape has been applied to either fix the 
problem, or to convince those involved to implement a more permanent solution.

There are other uses, but these are two common applications.

73,
Gordon Beattie, W2TTT
201.314.6964

Get Outlook for Android<https://aka.ms/ghei36>

________________________________
From: RFI <rfi-bounces+w2ttt=att.net@contesting.com> on behalf of KD7JYK DM09 
<kd7jyk@earthlink.net>
Sent: Wednesday, June 16, 2021 1:27:58 AM
To: Rfi List <RFI@contesting.com>
Subject: [RFI] EMI Tape?

Who's playing with this, what is your application, and results?

https://www.ebay.com/itm/121739046153

I've seen it in equipment since the 90's, bought a roll a couple years
ago, just haven't gotten around to using it.  Wondering what others are
doing.

Kurt
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