[TowerTalk] Feed Point Choke Question

[Jim Brown]

I will not be drawn into debates about scientific concepts that have 
long been well understood.

73, Jim K9YC

On 11/6/2020 12:58 PM, Artek Manuals wrote:
> Jim
> 
> Show me the ACTUAL antenna range pattern measurement data  with and 
> without the common mode choke on a a similar antenna, with a reasonable 
> SWR ( LESS THAN 1.5:1)  and the feed line has been brought down 
> perpendicular to the plane of the antenna and I will concede you the point
> 
> Dave
> NR1DX
> 
> 
> On 11/6/2020 3:37 PM, Jim Brown wrote:
>> On 11/6/2020 12:28 PM, Artek Manuals wrote:
>>> The short answer is how tight you make the turns will have little 
>>> real world effect. 
>>
>> That short answer is WRONG.
>>
>> Use the RG-8X I would probably use the #31 core over the
>>> 43 . The poor mans 8 turns of coax 4-5" in diameter without ferrites 
>>> will probably actually work as well. 
>>
>> Define "work." The important thing a choke should do is kill common 
>> mode current on the feedline that couples noise to the antenna and 
>> fills in nulls in the antenna's pattern. That "poor man's" solution 
>> won't do much for that. If "work" means it won't overheat, yes, it 
>> would "work."
>>
>>> Depending on SWR and feed line dressing (always perpendicular to the 
>>> plane of the beam the need for choke at all� is arguable
>>
>> It's arguable only if you don't understand the problem, or don't care 
>> about noise or the antenna's nulls.
>>
>> 73, Jim K9YC
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>