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Re: [TowerTalk] [Bulk] Re: BALUN revisited again

To: towertalk@contesting.com
Subject: Re: [TowerTalk] [Bulk] Re: BALUN revisited again
From: Jim Brown <jim@audiosystemsgroup.com>
Reply-to: jim@audiosystemsgroup.com
Date: Fri, 8 Apr 2016 16:47:39 -0700
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
On Fri,4/8/2016 11:36 AM, Bert Almemo wrote:
As I was reading the post I was wondering if you could use ferrites of
different mix in the same choke/balun? Would that work or not?

It could work for two chokes in series, as shown in the CMC-230-5K. But since the ferrite materials are not specified for this product, it's hard to say what they're using. It would make sense to use #31 for the lower frequency choke and #43 for the higher frequency choke.

I think the power rating for this choke and the BL2006-3K may be overly optimistic. I've fried a similarly constructed choke on a single #31 core with 1.5kW under heavy contest conditions with an 80M dipole. Plugging the equivalent circuit into an NEC model shows the need for at least twice the choking Z of a single choke. The second choke doesn't need to be at the feedpoint -- it could be well down the line.

73, Jim K9YC
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