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Re: [TowerTalk] Ferrite beads for common mode current

To: "jeremy-ca" <km1h@jeremy.mv.com>, <n7ka@comcast.net>,"TowerTalk" <towertalk@contesting.com>
Subject: Re: [TowerTalk] Ferrite beads for common mode current
From: Jim Lux <jimlux@earthlink.net>
Date: Wed, 25 Jul 2007 20:59:26 -0700
List-post: <mailto:towertalk@contesting.com>
At 06:05 PM 7/25/2007, jeremy-ca wrote:
>It aint easy getting 5 turns of RG-213 thru a 2.4" OD dia toroid!

not all that tough. I've got one sitting here in front of me. Don't 
do it outside on a cold day, though.

>The definitve tests for Fairite 43 Mix beads as a sleeve balun was 
>done in the early 80's and published in Scuttlebut and most likely 
>reprinted elsewhere.

Jim Brown's paper has very high quality measurements done with 
traceably calibrated lab gear (a VNA) on a wide variety of 
configurations.  Not that measurements done 20-30 years ago are not 
valid, but measurement technology has improved a lot, particularly 
for high insertion losses.   The ability to make the measurements 
more rapidly means you can make 30 measurements intead of one, and 
that lets you spend more time on doing good fixturing for the 
tests.  The other thing is that modern test equipment does fixture 
calibration for you.

(I want a Agilent 4 port PNA-X with the two sources and an E-cal for 
my garage, although I wish it went down to 300kHz like the N5230A!  I 
wouldn't turn down a more elderly 8753..)

Jim, W6RMK 


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