OK, here's some more things to think about. To create RF noise, the rise time
of any current pulse has to be very fast. If the rise time is slow, you won't
hear any RF noise. This is true even though the charge may cause a (very
slow) meter to deflect, or a charge may slowly build up and arc across a gap.
1.) The impedance problem. The charge transfer rate from the droplet to the
antenna is limited by the resistance of the path. A slow charge transfer rate
would mean "low noise". How good an insulator is fresh water? Charge up a
rubber comb and try to create an "arc". Touch it to your antenna connector.
Now try the same experiment with a metal foil attached to the open end of the
comb.
(If it was raining charged aluminum foil wrapped Hersey Kisses, I'd expect
droplet static.)
2.) A quad generally has the high impedance ends turned to the sides, with
the low impedance portions at the apex or highest point. If there is corona,
it will occur at lower impedance areas of the quad antenna. This will result
in a larger mismatch to the high impedance noise source and less corona
noise. But we could do the same by putting a spike above a yagi, and that did
work for me.
3.) If the droplet has such poor charge retention that simply passing close
to another grounded element or closer to earth "drains or reduces the
charge", why does it rapidly discharge and create noise when striking the
antenna? Why doesn't the droplet smoothly discharge at the rate of approach
to the antenna element?
Everything pointing towards corona fits the puzzle perfectly. The charged
droplet theory seems to have questionable science. Why not charge a stream of
water with a supply, and let the drops hit an antenna. If it creates noise,
it proves the drops can be a potential source of noise.
Weather can't be controlled during a contest, but maybe static can.
73 Tom
>From Lee Buller <k0wa@southwind.net> Mon Apr 29 21:42:19 1996
From: Lee Buller <k0wa@southwind.net> (Lee Buller)
Subject: Dayton Contest Dinner
Message-ID: <1.5.4.32.19960429204219.0067fde0@southwind.net>
Where can I get four tickets to the contest dinner at Dayton?
Lee
k0wa@southwind.net
>From w2vjn@rosenet.net (George Cutsogeorge) Tue Apr 30 04:38:51 1996
From: w2vjn@rosenet.net (George Cutsogeorge) (George Cutsogeorge)
Subject: Rain Static
References: <199604291715.KAA00731@desiree.teleport.com>
Message-ID: <M.042996.203851.10@ppp053.rosenet.net>
The quad antenna was originally designed that way to eliminate the corona that
forms on the ends of Yagi antennas when very high power is in use. This should
be a clue. It has to due not with the element diameter, but with the fact that
there is no end at the HV point.
Putting balls on the ends of the Yagi elements probably would help. Certainly
would make them look more macho.
George
----
George Cutsogeorge, W2VJN
Umpqua, OR.
>From Lee Buller <k0wa@southwind.net> Mon Apr 29 21:54:23 1996
From: Lee Buller <k0wa@southwind.net> (Lee Buller)
Subject: The Goldent Age of Radio
Message-ID: <1.5.4.32.19960429205423.00697e80@southwind.net>
I went to the estate sale of W0CY the other day. Jim had done a lot of
contesting in the 30s and 40s and 50s and 60s, but had given it all up to be
one of the founders of AMSAT. I purchased (FOR $5.00) QSTs from 1959 to
1964. I had a ball going through those mags looking at all the wonderful
rigs. The DX-20, 40 (34.00 bucks) and 60. The RME, Hallicrafters, National
and Hammarlund receivers. The early moden KWM-2 and what someone thought
would be a winner...the COSMOPHONE. Anyone ever used a Cosmophone
transcierver? RCA was activity selling tubes as was Eimac and Penta Labs
(PL-175s) Antennas had names like Hornet (Duncan OK) and Telrex and
Gotham...and Hygain...and Mosley. Radio Shack was in there too selling ham
gear and kits. Heathkit and Knightkit and Layfaette were in there as well.
Oh, yes, you could get a new 11-meter transceiver in there from Johnson
radio for 39.00 bucks. Of course, the had thier line up too, Adventurer,
Navigator, Ranger, Valiant, Thunderbolt.
Thats what I would like. A Kenwood Ranger with an Yaesu Thunderbolt with a
ICOM Apache for a standby rig.
Just killin' time at work...a slow Monday
Lee
k0wa@southwind.net
>From R. Torsten Clay" <torsten@mephisto.physics.uiuc.edu Mon Apr 29 21:58:10
>1996
From: R. Torsten Clay" <torsten@mephisto.physics.uiuc.edu (R. Torsten Clay)
Subject: Rain Static
Message-ID: <199604292058.AA28244@mephisto.physics.uiuc.edu>
> Putting balls on the ends of the Yagi elements probably would help.
> Certainly
> would make them look more macho.
>
I've seen old antenna ads for yagis where a loop is added to the end of each
element...I guess to stop corona discharge? Presumably they are no longer
used because they were a pain mechanically? Anyone know the story here?
Tor
n4ogw@uiuc.edu
>From Jim Hollenback" <jholly@hposl62.cup.hp.com Mon Apr 29 22:06:57 1996
From: Jim Hollenback" <jholly@hposl62.cup.hp.com (Jim Hollenback)
Subject: Rain Static
References: <199604291715.KAA00731@desiree.teleport.com>
<M.042996.203851.10@ppp053.rosenet.net>
Message-ID: <9604291406.ZM23459@hpwsmjh1.cup.hp.com>
On Apr 30, 3:38am, George Cutsogeorge wrote:
> Subject: Re: Rain Static
>
> Putting balls on the ends of the Yagi elements probably would help.
Certainly
> would make them look more macho.
>
The Urban Legend I heard about the quad, the balls on the ends of the
Yagi is what was done at HCJB before the quad was born. The balls
were specifically put there to prevent the corona at the ends.
YMMV, 73, Jim, WA6SDM
jholly@cup.hp.com
>From Douglas Zwiebel <KR2Q@worldnet.att.net> Mon Apr 29 22:44:34 1996
From: Douglas Zwiebel <KR2Q@worldnet.att.net> (Douglas Zwiebel)
Subject: corona balls
Message-ID: <199604292144.VAA17843@mailhost.worldnet.att.net>
Corona balls and static? NAHHHHHH!
Corona balls (as stated) are for those guys running SOUP. If you don't
have corona balls, the ZAP comes off of the edge of the element and can
do much damage (not much area to carry the current). Corona balls have a
lot of SURFACE AREA and disburse the ZAP so as not to damage the element
tips. You still get coronal discharge, but now it doesn't hurt the antenna.
:-)
PS...am I really that old that nobody else knows that Telrex antennas used
corona ball? :-(
de Doug KR2Q
>From zettel@homer.libby.org (Steve Zettel) Tue Apr 30 00:23:47 1996
From: zettel@homer.libby.org (Steve Zettel) (Steve Zettel)
Subject: Rain static and grounded elements
Message-ID: <v02140b01adaafeb38bd0@[192.0.2.1]>
Perhaps I am overlooking the obvious, but early on in this thread there was
mention of "grounding", or giving a path for discharge to ground, of the
ungrounded Force 12 elements and boom. Would it upset the RF applecart to
place a several hundred K or Megohm resistor from each element to boom, and
boom to tower or ground lead--maybe even to the shield of the coax? Sort of
the same idea as the discharge path for precip static used on shipboard
vertical whips.
Just a thought,
Steve Zettel KJ7CH kj7ch@libby.org
Libby, MT USA steve.m.zettel@usace.army.mil
Take a tour of NW Montana at: http://www.libby.org
>From John Brosnahan <broz@csn.net> Tue Apr 30 00:34:20 1996
From: John Brosnahan <broz@csn.net> (John Brosnahan)
Subject: corona balls
Message-ID: <199604292334.RAA16721@lynx.csn.net>
>PS...am I really that old that nobody else knows that Telrex antennas used
>corona ball? :-(
>
>de Doug KR2Q
NO, you are not alone. BUT do you remember the Telrex
carpet beater tips that had an aluminum loop at the
ends of the elements. Probably 16 inches long and
6 inches wide and made from 1/8 inch (approx)
aluminum wire or rod. Provided the coronal ball
effect as well as making a mechanical damper for
element oscillation. Exact resonance was somewhat
dependent on the shape that they deformed into.
(I have to contend with Golden Eagles and Great Horned
Owls sitting on my antennas.)
BTW My preference is for a signal with balls,
not just an antenna. <;-)
73 John W0UN
John Brosnahan
La Salle Research Corp 24115 WCR 40 La Salle, CO 80645 USA
voice 970-284-6602 fax 970-284-0979 email broz@csn.net
>From Neal Sulmeyer <ae6e@akorn.net> Tue Apr 30 00:37:59 1996
From: Neal Sulmeyer <ae6e@akorn.net> (Neal Sulmeyer)
Subject: Elevation rotation of HF arrays
References: <199604250547.BAA13994@paris.akorn.net>
Message-ID: <318552D7.6F65@akorn.net>
Larry Tyree wrote:
>
> Back in the 70's, Brad Fisher, WB6YBL, operated contests from Rainbow Ridge
> ("home" of N6DX). This is a cliff top type station with very little ground
> to reflect off of.
>
> They had a big 20 meter beam with an elevation rotator and Brad would
> report a 10 db improvement with it pointing about 45 degrees up in the
> air on stateside signals.
>
> Just an empirical data point to factor into the discussion.
>
> Tree (don't forget the internet sprint) N6TR
> tree@contesting.com
The first iteration of this was a 5el on about 50' boom and at 100'. I
would say not quite 10db! It was more like 5 or 6db of which 3db was
signal to noise. Soon afterwards we built a 7el on 100' boom (made of Al
tower sections) and beefed up the Az-El mount on the pole. All that
probably resulted in an additonal 1 to 2db.
The crux of all this is that we found that the optimum angle varied with
the propagation factors. The highest angles used were about at about 60
degrees. More typical was 35 to 40 degrees. I think a better solution
to the problem is with a stacked yagi array an variable (or
incrementally switchable) phase feed system.
73's...
Neal, AE6E
>From Ward Silver <hwardsil@wolfenet.com> Tue Apr 30 00:43:57 1996
From: Ward Silver <hwardsil@wolfenet.com> (Ward Silver)
Subject: New Findings on the Not-So-"Quiet" Sun Subject of May 2 Update (fwd)
Message-ID: <Pine.OSF.3.93.960429164219.17225C-100000@gonzo.wolfenet.com>
An interesting press release that might be of interest.
73, Ward N0AX
---------- Forwarded message ----------
From: NASA HQ Public Affairs Office <NASANews@luna.osf.hq.nasa.gov>
To: press-release-edu2@mercury.hq.nasa.gov
Subject: New Findings on the Not-So-"Quiet" Sun Subject of May 2 Update
Don Savage
Headquarters, Washington, DC April 29, 1996
(Phone: 202/358-1547)
Jim Sahli
Goddard Space Flight Center, Greenbelt, MD
(Phone: 301/286-0697)
NEW FINDINGS ON THE NOT-SO-"QUIET" SUN SUBJECT OF MAY 2 UPDATE
Initial findings from the recently launched Solar and
Heliospheric Observatory (SOHO), as well as dramatic new
images and movies, will be presented at a Space Science
Update (SSU) scheduled for 1 p.m. EDT Thursday, May 2. The
SSU will originate from the NASA Headquarters Auditorium,
300 E St., SW, Washington, DC, and will be carried live on
NASA TV with two-way question-and-answer capability for
reporters covering the event from participating NASA centers.
Astronomers will report new information on strange
"plume" structures in the atmosphere of the Sun, shown in
new high-resolution ultraviolet movies from SOHO which
reveal the source of long, feathery plumes that extend to
high altitudes from regions near the poles of the Sun. To
investigators' surprise, SOHO instruments show that there
are continuous disturbances on the Sun although it is in a
supposedly "quiet" period near the minimum of the 11-year
sunspot cycle.
> Forwarder's note: Yeah, we know...ask any DXer! ;-)
Participants in the Space Science Update will be:
Dr. Joseph Gurman, Goddard Space Flight Center (GSFC), MD.
Dr. Craig E. DeForest, Stanford University, Stanford, CA.
Dr. Andrea K. Dupree, Harvard-Smithsonian Center for Astrophysics,
Boston
Dr. P.Brendan Byrne, Armagh Observatory, N. Ireland
Dr. Stephen P. Maran, GSFC, will be the panel moderator.
Audio of the broadcast will be available on voice
circuit from the Kennedy Space Center at 407/867-1260.
- end -
NASA press releases and other information are available
automatically by sending an Internet electronic mail
message to domo@hq.nasa.gov. In the body of the message
(not the subject line) users should type the words
"subscribe press-release" (no quotes). The system will
reply with a confirmation via E-mail of each subscription.
A second automatic message will include additional information
on the service. NASA releases also are available via CompuServe
using the command GO NASA.
>From Ward Silver <hwardsil@wolfenet.com> Tue Apr 30 00:48:35 1996
From: Ward Silver <hwardsil@wolfenet.com> (Ward Silver)
Subject: Yagi Balls
Message-ID: <Pine.OSF.3.93.960429164426.17225E-100000@gonzo.wolfenet.com>
On Tue, 30 Apr 1996, George Cutsogeorge wrote:
> The quad antenna was originally designed that way to eliminate the corona
> that
> forms on the ends of Yagi antennas when very high power is in use. This
> should
> be a clue. It has to due not with the element diameter, but with the fact
> that
> there is no end at the HV point.
>
> Putting balls on the ends of the Yagi elements probably would help.
> Certainly
> would make them look more macho.
>
Corona discharge was the reason for the invention of the quad antenna by
Clarence Moore in the late 40's (1949?) at HCJB near Quito, Ecuador. This
high-altitude site had such thin air that the high-power SW transmitter of
several kW caused ferocious corona at the element tips of the yagi
originally installed. So ferocious that the metal melted and slowly
consumed the elements! After trying all sorts of things like metal balls,
loops, etc. Clarence hit upon the idea of an antenna element with no
ends...and thus the quad was born. There's quite a good relation of the
full story in Bill Orr's book on quads.
I'm suprised one of the California DXers of the 30's didn't discover this
earlier! (snicker) Of course, they didn't live in the mountains, either.
73, Ward N0AX
>From John Brosnahan <broz@csn.net> Tue Apr 30 00:59:41 1996
From: John Brosnahan <broz@csn.net> (John Brosnahan)
Subject: Rain static and grounded elements
Message-ID: <199604292359.RAA28182@lynx.csn.net>
zettel@homer.libby.org (Steve Zettel)
At 05:23 PM 4/29/96 -0600, you wrote:
>Perhaps I am overlooking the obvious, but early on in this thread there was
>mention of "grounding", or giving a path for discharge to ground, of the
>ungrounded Force 12 elements and boom. Would it upset the RF applecart to
>place a several hundred K or Megohm resistor from each element to boom, and
>boom to tower or ground lead--maybe even to the shield of the coax? Sort of
>the same idea as the discharge path for precip static used on shipboard
>vertical whips.
My concern with small wattage resistors used in this fashion
is that they will "disappear" in the event of any nearby
lightning strikes. Even running 20W Glowbar resistors in
my Beverages means that some disappear from time to
time.
A direct DC short from the center of the element
to the boom will usually work. W0ZV used to always
ground the centers of his KLM monobanders as
well as his KLM tribanders. There should be no
effect in general since the center is at a voltage null.
But there has been a concern that in multiband antennas
there might be some additional parasitic resonances
associated with the added length of the boom sections
combining with the elements.
To provide a DC ground but reduce the chance of
parasitic resonances (IF this is indeed a real
problem) you could always try RF chokes, but
use serious ones such as #10 wire on ferrite rods
like those that are used for filament chokes but with
only one winding.
I would always look for any parallel resonances in the
chokes by shorting the end of the winding together
and exploring for any resonances with a grid dip meter.
Although this shouldn't even be a problem since a DC short
should also work.
For split driven elements you'd need two of the chokes,
one for each half of the element. This is a 50 ohm point
and two chokes designed to go as low as 80 and 160
meters should show enough reactance to handle 1.5 KW
on 20 through 10 meters. There is still the possibility
that one could get some nonlinearity in the chokes
due to high power that might result in intermod--something
that would need to be explored. One quick way to look
for problems when doing this is to measure the VSWR
before and after the chokes are installed--if their is
any difference then there is the possibility of a problem.
Bottom line--go with grounded elements if possible.
73 John W0UN
John Brosnahan
La Salle Research Corp 24115 WCR 40 La Salle, CO 80645 USA
voice 970-284-6602 fax 970-284-0979 email broz@csn.net
>From Ward Silver <hwardsil@wolfenet.com> Tue Apr 30 01:00:58 1996
From: Ward Silver <hwardsil@wolfenet.com> (Ward Silver)
Subject: Rain static and grounded elements
Message-ID: <Pine.OSF.3.93.960429165224.17225F-100000@gonzo.wolfenet.com>
On Mon, 29 Apr 1996, Steve Zettel wrote:
> Perhaps I am overlooking the obvious, but early on in this thread there was
> mention of "grounding", or giving a path for discharge to ground, of the
> ungrounded Force 12 elements and boom. Would it upset the RF applecart to
> place a several hundred K or Megohm resistor from each element to boom, and
> boom to tower or ground lead--maybe even to the shield of the coax? Sort of
> the same idea as the discharge path for precip static used on shipboard
> vertical whips.
>
This will work great...just make it at least 1/2-watt, and preferably
larger so that it can withstand transients. You should use a carbon-comp
(able to withstand pulse overloads much better than film types and
non-inductive, to boot) resistor and protect it from the weather. Check
it every once in a while (voltmeter in the shack works great) because a
large transient from a nearby lightning discharge will probably blow it to
smithereens.
73, Ward N0AX
>From Mr. Brett Graham" <bagraham@HK.Super.NET Tue Apr 30 01:06:23 1996
From: Mr. Brett Graham" <bagraham@HK.Super.NET (Mr. Brett Graham)
Subject: Antenna input sought
Message-ID: <199604300006.IAA08682@is1.hk.super.net>
N7ENU asked:
What do y'all think of putting a vertical antenna on top of a tower that
has a tri-band beam presently installed.
I believe this is what XU6WV is running at the moment - an HF2 mounted a
meter or so above an A3, all on a short roof tower. If I recall correctly,
Mike got it working by setting the HF2 up all by itself with proper radials
for tweaking the radiator & then moved the HF2 to its final position. He
then trimmed the final radials, which obviously have to be below everything
that rotates, until the HF2 was resonant where it was originally. The end
result is an antenna that seems to work pretty good.
K7SS years ago (nearly 20, come to think of it!) used to have a
quarter-wave 40m vertical mounted on top of a TH6 which was perched atop a
tall tree. I don't recall what Danny did for a counterpoise, but I believe
it played well, too. You might want to talk to him about it.
73, VS6BrettGraham bagraham@hk.super.net & vr2bg@harts.org.hk
>From Rod Greene <w7zrc@micron.net> Tue Apr 30 01:13:00 1996
From: Rod Greene <w7zrc@micron.net> (Rod Greene)
Subject: Going to Dayton?
Message-ID: <m0uE34F-000iHLC@majordomo.micron.net>
Lee, Hope to see many of you there. I will be staying at Stouffers and
going to the banquet. 73, Rod
>Who is all going to Dayton this year? And...who will attend the contest get
>together at the Stouffers?
>
>Lee Buller
>k0wa@southwind.net
---- Rod Greene Boise ID - DN13UN - w7zrc@micron.net <>< ----
>From Robert <w5robert@blkbox.COM> Tue Apr 30 02:52:45 1996
From: Robert <w5robert@blkbox.COM> (Robert)
Subject: TREE
Message-ID: <9604292052.aa21088@blkbox.COM>
On the cover of "CQ Contest" cover is a picture of the
contest tree just left of center at PY5EG's. The gene's
of this tree where done by a ham? It appears
to be made for a 15-4 to be layed on top. A side mount
is possible half way up. And dipole supports only at the top!
I understand these antennas were removed for the picture?
--
73 Robert WB5CRG w5robert@blkbox.com
>From Bernie McClenny, WR3E" <bernie.mcclenny@mail.wdn.com Tue Apr 30 07:27:13
>1996
From: Bernie McClenny, WR3E" <bernie.mcclenny@mail.wdn.com (Bernie McClenny,
WR3E)
Subject: Need email address for KV5V
Anyone have an email address for KV5V? de Bernie
Please don't waste ur time flaming me!
**************************************************************************
* Bernie McClenny, WR3E (ex WB3JRU) *
* bernie.mcclenny@mail.wdn.com *
* Promise Keeper <>< *
* But as for me and my house we shall serve the Lord. Joshua 24:15 *
**************************************************************************
>From Dan Robbins <kl7y@alaska.net> Tue Apr 30 03:27:39 1996
From: Dan Robbins <kl7y@alaska.net> (Dan Robbins)
Subject: Rain Static
Message-ID: <9604300227.AB11120@alaska.net>
At 11:13 AM 4/29/96 -0400, you wrote:
I'd be willing to bet the "rain drop discharge" is folklore,
>and the real problem is corona discharge.
>
>73 Tom
Tom,
I suspect rain drops bleed charges from the atmosphere to the ground, but I
don't know for sure if this causes precipitation static. I do know corona
discharge from antenna and towers is real and it does cause the familiar
frying eggs static. This is pretty evident: 1) the static often occurs
before it starts raining 2) I have seen the blue glow from the corona off
of an antenna when it was not yet raining and static was happening, and 3)
I have felt the HV corona buildup from an approaching storm strong enough to
make my hair stand on end. In the latter case I could "skywrite" in corona
blue with an upraised index finger. Fortunately, the eerie wonder of this
moment was not shattered by lightning, but a hasty retreat down from my perch.
If the noise is much worse on the top antenna than a lower one, I would
almost certainly bet corona discharge is the cause - the top antenna is much
closer to the noise generator. If the cause was charged rain drops falling,
then an large antenna would accumulate much more charge than a small one. I
do not see this.
There is also windblown static, especially when dust, sand or dry snow are
blowing. I remember one bad windstorm on a clear night that generated
flashes in the mountains almost like lightning. Blowing snow was the cause,
so windblown static can have a pretty healthy (or unhealthy) voltage
generator behind it.
Anyway, that's my two cents.
Dan KL7Y
|