I built a homebrew 160m array (not YCCC) and completely disagree with
what they say. I have four 30 foot radials under each vertical. The
verticals are 30 feet high with four umbrella wires. They are fed with
a 300 ohm to 75 ohm isolation transformer at the antenna. A common mode
choke is completely unnecessary IMHO since the transformer breaks the
connection from the coax shield to the ground radials. The feedline is
NOT part of the grounding. All looks good on EZNEC, and it seems to work
well listening on the air. YMMV.
---
Rick Karlquist
N6RK
On 2021-09-23 12:07, Hans Hammarquist via TowerTalk wrote:
> My feeling is that the feed-line to each radiator is part of the grounding.
> You have 9 radiators. If you have 1/4 wavelength between each element you
> would have about 3/4 wavelength between each element and the center. I assume
> you have placed the combiner in the center. An open end wire (any type) is
> not that bad of a grounding radial. The common mode choke is there to isolate
> the feed-line from the combiner and that way act like an open end.
>
> Hans - N2JFS
>
> -----Original Message-----
> From: Roger Parsons via TowerTalk <towertalk@contesting.com>
> To: Tower and HF Antenna Construction Topics. <towertalk@contesting.com>
> Sent: Thu, Sep 23, 2021 2:50 pm
> Subject: [TowerTalk] YCCC 9 Circle Receive Array
>
> 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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