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Re: [TowerTalk] Balun Recommendation

Subject: Re: [TowerTalk] Balun Recommendation
From: Ian White GM3SEK <>
Reply-to: Ian White GM3SEK <>
Date: Tue, 24 Apr 2012 14:41:58 +0100
List-post: <">>
Steve Hunt wrote:
>Yes, when the choke reactance and the CM path reactance have the same 
>sign there's a bonus. But what I was actually trying to show in that 
>analysis is that the CM path reactance may have an upper limit; and if 
>that's the case, even when the signs are opposite there may still be a 
>very useful contribution from the choke reactance.
>Jim's own figures show a #61 choke having >5000 Ohms reactance over a 
>2:1 frequency range; if the worst-case path reactance is 2000 Ohms, we 
>know that choke is going to provide a "net" 3000 Ohms impedance over 
>that frequency range, no matter what. That seems to me pretty useful, 
>particularly as it will handle a lot more power than an equivalent 3000 
>Ohm choke wound on one of the lossy mixes.
>I'm simply questioning whether we have too readily dismissed reactive 
>chokes because "only a choke's resistance counts".

What I have said (and consistently, I hope) is that "only the choke's 
resistance is completely DEPENDABLE" for solving RFI problems.

Your insight is a very valuable one, and it may well explain why even 
quite inferior on the test bench may work well enough in practice.


73 from Ian GM3SEK

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