[Antennas] RG-178 balun turns count

[Danny]

Yes that is correct and the five times rule is marginal at best - even 
for fifty-ohm feed point antennas.

Here are a couple of URLs that have good papers on the subject and the 
reasons that the choking impedance should several times greater than the 
five time rule.

http://www.ifwtech.co.uk/g3sek/in-prac/inpr1005_ext_v1.pdf

and

http://audiosystemsgroup.com/RFI-Ham.pdf

73,
Danny, K6MHE


On 07/01/2010 10:09 AM, Brian Cake wrote:
>      That rule of thumb does not apply to off-center-fed antennas, such as
> the C pole, where the common mode potential at the feedpoint can be high.
>
>      73
>
>      Brian KF2YN
> ----- Original Message -----
> From: "Roy"<royanjoy at ncn.net>
> To:<Antennas at mailman.qth.net>
> Sent: Thursday, July 01, 2010 12:47 PM
> Subject: Re: [Antennas] RG-178 balun turns count
>
>
>    
>> About:
>>
>> "I have a 2" diameter coil form. How do I calculate/test for the number
>> of turns required to be an effective choke at 14MHz?"
>>
>>
>> The old rule is to aim for five times the reactance in the coil than the Z
>> of the load....5 X 50 = 250 ohms.
>>
>> 73,    Roy     K6XK
>>
>>
>>
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>>      
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