Perhaps just wild speculation but seems like everything I've heard on a subject
I've paid little attention to here....But could it be just the 'capture area'
as it used to be put in the old 'quad vs. yagi' debate has something to do with
it. Having a large antenna up high on your tower capturing the static charges
and eliminating them for the most part from the lower antennas. Just a thought
but I think it's as good so far as about any of them.
Terry
KI7M
> On December 8, 2018 at 8:36 PM Grant Saviers <grants2@pacbell.net> wrote:
>
>
> I agree with K1TTT's analysis. Another factor contributing to which
> antennas are noisy is how the stack is arranged. If it is the classic
> "Christmas Tree" layout with smallest yagi on top then that provides
> limited "shielding" of the voltage gradient to the lower antennas. My
> stack has 80m 100' long elements on top and all below it are quiet.
>
> I think geometry differences and/or a difference in the site matter.
> Yagis have lots of discharge points, ie sharp edges. Quads usually
> don't and the feedpoints aren't at the top and wire insulation may make
> a difference. Also, note one recent TT post reporting that a ground wire
> around the rotator bearings tamed the noise. A ball bearing oil film
> has a breakdown voltage around a few dozen volts, in my experience. So
> if there is arcing across the oil film the entire mast and assembly is
> bouncing around in voltage.
>
> IMO it doesn't matter if the driven elements are grounded. A current in
> any yagi element discharging voltage from its tip is going to introduce
> noise into the driven element. The corona itself is a broadband white
> noise source so can be picked up by other antennas. But the fact that
> lower ones can be quiet tends to reinforce the idea that the current in
> the discharging elements is the larger contributor.
>
> Regarding charge accumulation from water and snow landing on the
> antenna, there is a lot to learn from the aviation world. However,
> aircraft are certainly contacting enormously more charged particles than
> precipitation landing on an yagi. What is interesting are the devices
> added to aircraft to dissipate the charge and eliminate radio interference.
>
> https://en.wikipedia.org/wiki/Static_discharger
> https://www.aviationpros.com/article/10386443/precipitation-static-combating-noise-and-other-effects
> https://apps.dtic.mil/dtic/tr/fulltext/u2/261029.pdf
>
> Next time I have noise, I will check my top 4L SteppIR for its noise
> level. It's on a tower separated from the stack. If the logic re quads
> is correct then a SteppIR being fully insulated should be quiet.
>
> Grant KZ1W
>
>
> On 12/5/2018 2:48 AM, Máximo EA1DDO_HK1H wrote:
> > It is an interesting thing, because many Yagi have the dipole at DC ground,
> > at the center support, part of the gamma-match system.
> > I wonder if these Yagi suffer same rain noise.
> > By the way, not every Quad uses Gamma feed. Most are balun and coax feed.
> >
> > 73, Maximo
> >
> >
> > ________________________________
> > De: TowerTalk <towertalk-bounces@contesting.com> en nombre de Alton
> > McConnell <amcconnell3@hotmail.com>
> > Enviado: miércoles, 5 de diciembre de 2018 10:26
> > Para: TowerTalk@contesting.com
> > Asunto: [TowerTalk] Quad elements no rain static.
> >
> >
> > I believe the reason why quads do not exhibit rain or snow static is
> > because the driven element is at DC ground.
> >
> > I feed mine with a tri gamma match
> >
> > Sent from Samsung tablet
> > _______________________________________________
> >
> >
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