[TowerTalk] Fwd: YCCC 9 Circle Receive Array

[Peter]

All

" The chokes at the combiner prevent all the feedlines together them 
from acting like a ground screen. Without the chokes, they are all RF 
bonded together.
John W1FV explained this in his original NCC paper how it upsets the 
pattern. "

Those papers can be find het PI4CC Contest Club 
<https://www.pi4cc.nl/tech-info/rx-array/>

Peter
-------- Doorgestuurd bericht --------
Onderwerp: 	Re: [TowerTalk] YCCC 9 Circle Receive Array
Datum: 	Thu, 23 Sep 2021 13:34:21 -0600
Van: 	VE6WZ_Steve <ve6wz at shaw.ca>
Aan: 	Roger Parsons <ve3zi at yahoo.com>
CC: 	Tower and HF Antenna Construction Topics. <towertalk at contesting.com>



Roger,

Each HI-Z amp (impedance buffer) at each element already has a 1:1 
“braid breaker” choke at the input so is already isolated from the feedline.

The chokes at the combiner prevent all the feedlines together them from 
acting like a ground screen. Without the chokes, they are all RF bonded 
together.
John W1FV explained this in his original NCC paper how it upsets the 
pattern.

I have thought about redesigning the combiner board with integrated 1:1 
toroid braid-breakers on each feedline (just like the element amps) but 
haven't got around to that.
That would be a lot cheaper and easier than installing out-board chokes.

Steve, ve6wz

> On Sep 23, 2021, at 12:50 PM, Roger Parsons via TowerTalk 
> <towertalk at contesting.com> wrote:
>
> I have recently completed building a YCCC 9 Circle array, and it seems 
> to work quite nicely. This replaces a receive 4 square using top 
> loaded elements - I could never get that to last as animals would 
> break one or more of the top loading wires mistuning the array.
>
> The instructions for the YCCC array are explicit that there must be 
> common mode chokes between each element and the combiner unit. That is 
> obviously a good idea, but I can't understand why they suggest putting 
> them at the combiner unit end of the feed lines to each element, and 
> my feeling is that they should be at the element ends. (The elements 
> have a very poor ground, and the feed lines are significantly long. 
> Surely that means that the high impedance of a common mode choke at 
> the combiner will be transformed to a different and probably lower 
> impedance at the element. The effect of that could be that the feed 
> line becomes the main and unpredictable ground for the element, and 
> different for each element, which I think is exactly what is not 
> required.)
>
> Comments would be appreciated.
>
> 73 Roger
> VE3ZI
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk

_______________________________________________



_______________________________________________
TowerTalk mailing list
TowerTalk at contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk