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Re: [TowerTalk] CMC-230-5K

To: towertalk@contesting.com
Subject: Re: [TowerTalk] CMC-230-5K
From: Jim Brown <jim@audiosystemsgroup.com>
Reply-to: jim@audiosystemsgroup.com
Date: Tue, 19 Apr 2016 10:06:02 -0700
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
There's something I don't understand here. In 2007, I published the research upon which all of this is built, with measured data for a broad range of chokes for the ham bands, and with full instructions for buying the cores at very good prices, and a "cookbook" for the various ham bands. Why in hell would you want to pay someone 3x the cost of doing it yourself, when all you have to do to do it yourself is wind turns of coax through ferrite cores?

AND -- l would not trust any published power ratings for ANY chokes without understanding the common mode voltage that they will see in any given installation. To do that, you've got to put them in an NEC model that approximates YOUR installation. Simply putting one of these chokes in a sealed enclosure greatly reduces its power handling because it greatly reduces air flow around the choke.

73, Jim K9YC

On Tue,4/19/2016 3:30 AM, Jim Thomson wrote:
I just received a pair of  CMC-230-5K  common mode chokes...from MyAntennas.com 
to experiment with.
They are configured as a  line isolator, with  silver-teflon  SO-239s  on each 
side.  They can also be configured as
a balun, with a pair of standoffs on the balanced ant side if you like.   
Extremely well designed and built, better
than I expected.

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