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Re: [TowerTalk] Type 31 baluns

To: Jim Brown <jim@audiosystemsgroup.com>
Subject: Re: [TowerTalk] Type 31 baluns
From: Kevin Normoyle <knormoyle@surfnetusa.com>
Date: Tue, 01 Jun 2010 21:11:51 -0700
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
On 6/1/2010 8:10 PM, Jim Brown wrote:
>> We started this saying the baluns at balundesigns could be outdone. I've
>> >not seen the one true answer that makes me believe that yet.
>>      
> One true answer? Gee, I've published measured data and showed exactly what
> I measured and how I measured it. Have you gotten that from any mfr of any
> balun or similar product?
>
>    
I don't care about manufacturers. I'm just trying to decide what to make.

You also showed that 12-16 turns of #14 THHN on a single type 31 core 
can have a much flatter response than the coax chokes, right?

You never showed that 10-12 turns of RG-400 wrapped normally with say 1" 
coils on the same type 31 core, is worse than the turn count you gave 
for #14 THHN. on the same core. At least not that I can tell?

If you did,  then you've shown that bifilar is better, with a few more 
turns. (for 3.5mhz-30mhz).

Even though we can agree the measurement technique by balundesigns might 
be suspect, you have no data that their 10-12 turn small coax design is 
bad, unless you're confident they're not using type 31 ferrite.

I want something with more voltage breakdown than the PVC on THHN. So I 
have my two choices: bifilar #16 teflon awg and RG400, wound some number 
of times around some number of cores.

You've not run your #14 THHN at 1500 watts for any period of time. 
Anecdotal info seems to suggest eventually I might have a problem. Even 
though it's fine for matched swr, what happens when you accidently drive 
1500 watts into the wrong antenna?

I read your paper, and I think you're showing bifilar is superior to the 
coax chokes you have, but it's unclear whether small diameter coax is as 
bad as you suggest, with the same winding/core. If it is, then it's 
obvious I should go bifilar.

Am I misunderstanding?

-kevin

-kevin


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