[TowerTalk] 40M rotary dipole

[Stan Stockton]

A question regarding chokes for K9YC.

Let's assume a coax going to an antenna is buried to the tower, the shield is grounded with a short length at the base, the coax is inside the tower and the shield is electrically bonded to the top of the tower and anything else that would be considered good practice for a good RF and lightning ground.

How is common mode noise making its way to the feed point and back to the receiver if you have something less than multiple cores at the feed point of the antenna?

Stan, K5GO

Sent from Stan's IPhone



> On Sep 20, 2017, at 3:45 PM, Stan Stockton <wa5rtg at gmail.com> wrote:
> 
> Dave,
> 
> I hope you do put it up with a temporary choke and then replace it one afternoon with the 6 toroid choke.  
> 
> Take notes or record to document the difference in receive noise.  I am interested since I am and always have been in position of "what you don't know doesn't hurt you."
> 
> I have never had a "proper" choke on any antenna in 50 years of being a ham and really want to know what I'm missing.
> 
> 73.. Stan, K5GO
> 
> Sent from Stan's IPhone
> 
> 
> 
>> On Sep 20, 2017, at 9:31 AM, Dave Sublette <k4to at arrl.net> wrote:
>> 
>> Thanks for all the suggestions on the RF choke.  I read the article by K9YC and concluded that the best approach wold be to wind RG8X around 6 Fair-Rite toroids made from type 31 material and 2.4 inches in diameter.  The big problem is they are listed at over $17 each from the distributors.  I will need 18 of them eventually.  6 each for this dipole and two more yagis.  That’s a large price tag, but still cheaper (and better performing) than the commercial units available, according to K9YC.
>> 
>> I have (again at the suggestion in the paper by K9YC) sent a request for quit to Fair-Rite, asking what quantity I would have to buy in order to get “a decent price”.  It might work out that I could make a large purchase and offer kits of toroids to the group.  I’m not looking to make money.  I only want to have a good choke at the lowest price I can find.
>> 
>> I may put the antenna up with a temporary choke on it and replace it when/if I can get the toroids.
>> 
>> I will keep you informed as to what I find.
>> 
>> I appreciate your inputs on this project.  It’s been fun.
>> 
>> Dave, K4TO
>> 
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