[TowerTalk] YCCC 9 Circle Receive Array

[Roger Parsons]

Thanks for the replies and particularly Steve and Peter.

For reasons that are now obscure I never read the second part of the YCCC article (or if I did immediately forgot it....) and  follow the reasoning.

I do have some doubts about how effective the 470uH chokes would be, but they must provide some isolation and presumably enough. And wonder why my RX 4 square had a good pattern with no common mode choking during the short periods that the elements were undamaged. 

Anyway, thanks again.

73 Roger
VE3ZI



On Thursday, 23 September 2021, 15:34:23 GMT-4, VE6WZ_Steve <ve6wz at shaw.ca> wrote: 





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

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