Verticals, Radials, Grounds, Lightning
RKILE at delphi.com
RKILE at delphi.com
Thu Aug 25 00:04:17 EDT 1994
While the emphasis has been on BIG low band antennas, there are
residential alternatives yet discussed. I have found it quite possible to
build good performing verticals for 160 at heights less than 65 ft 1/8
wavelenght. These have been simple systems that involve heavy top loading
by using existing tri-bander and additional wire to resonate the antenna
well into the broadcast band equivalent to 3/8 wave antenna and shunt fed.
These antennas had modest ground systems to say the least, often just a
dozen or so short radials. (Poor ground conductivity)
You poor folks who live in the South absolutely have to plan for
lightning. N4ZR quotes "Pay the piper now or later". It might also be said
if the ground surge doesn't get you induced voltages will. The Polyphaser
Book on the subject is quite comprehensive on the subject of lightning and
grounds. It should be noted that the topic of perimeter grounds on buildings
and towers refers to dc lightning protection and not RF grounding although
they tend to intermingle.
In the least I would highly suggest perimeter grounding and specifically
the dropping of all cables to ground level. Tie shields to ground at the
base of the towers with mov protectors on rotor cables at the tower base and
grounding rotor cables to tower base when not in use. I would stay away from
antennas and or towers attached to the building. Whole house protectors at
the service panel with in line cordset protectors for the most sensitive
While living in Seattle with a 100 ft back yard tower lightning struck a
utility transformer about 300 ft away. I suffered no ills although the
houses connected to that drop had their entire panels and household wiring
vaporized. I was using "modest protection".
via internet"rkile at delphi.com"
>From stevem at w8hd.org (Steve Maki) Thu Aug 25 05:51:43 1994
From: stevem at w8hd.org (Steve Maki) (Steve Maki)
Date: Thu, 25 Aug 1994 00:51:43 -0400
Subject: Rohn Tower Basing
Message-ID: <199408250451.AAA09693 at w8hd.w8hd.org>
>Talked with Rohn today, and they tell me that they emphatically recommend
>this type of base arrangement over the embedded tower section because at
>"ultimate wind load" it is better for the tower to be free to pivot at
>its base slightly, rather than to have all three legs firmly fixed. They
>claim this reduces the risk of broken welds, etc. that could result in a
>concealed weakening of the tower.
Single point mounting is used on virtually all large commercial guyed towers
for the reasons Rohn stated.
However the Rohn implementation (flat plate on concrete) negates much of the
theoretical advantage. I have been at the base of such an installation
during high winds and observed the top of the tower (130' of 45 with 2 large
beams on top) being twisted 10-15 degrees, while the base was still.
My gut feeling is that in most ham installs, Rohn tower is not overstresed
by a little twist over the length of the tower, but for complete peace of
mind, double guys (with special spacing brackets) at the top and any other
heavily loaded spots on the tower are the way to go.
Hey, I just had an idea for a new product!
Steve Maki K8LX
stevem at w8hd.org
>From Lyndon Nerenberg <lyndon at canada.unbc.edu> Thu Aug 25 06:47:26 1994
From: Lyndon Nerenberg <lyndon at canada.unbc.edu> (Lyndon Nerenberg)
Date: Wed, 24 Aug 1994 22:47:26 -0700 (PDT)
Subject: more on elevated radials
Message-ID: <Pine.3.89.9408242208.E10457-0100000 at canada.unbc.edu>
> Elevated radials: great for low band antennas!
I, too, have experience with the Butternet HF-6 running both ground mount
and elevated at the same QTH. The antenna was equipped with four tuned 1/4
wave radials for 80-10m.
I initially ran it ground mounted with the radials lying on the ground.
Later, I moved it to the garage roof (about 15 feet AGL) about 12 feet
due west of its original location.
Performance on the ground was significantly better. on 80m I had 140 KHz
bandwidth between the 2:1 SWR points. When moved to the roof that dropped
to roughly 50 KHz. (The antenna was completely retuned when I elevated it.)
Overall performance in the elevated position was noticeably worse.
It wasn't until after I moved that I realized the vertical, when ground
mounted, was planted almost in the middle of the drainage field for the
septic tank. We had really cruddy water, so everything draining from that
tank had passed through a water conditioned along the way, thus getting
loaded up with salts and doing wonderful things to the ground
conductivity. If I'd only known ... I probably would have put up a four
--lyndon VE7TCP/VE6BBM (where's that bag of salt? i'm sick of cutting
the lawn, anyway!)
>From Victor Burns <vburns at netcom.com> Thu Aug 25 00:11:29 1994
From: Victor Burns <vburns at netcom.com> (Victor Burns)
Date: Wed, 24 Aug 1994 16:11:29 -0700 (PDT)
Subject: V31DX CQWW SSB-'94
Message-ID: <Pine.3.89.9408241538.A19610-0100000 at netcom11>
V31DX will operate from Ambergris Caye per usual in the CQWW SSB and CW
contests later this year in the Multi-Single catagory hoping to raise our
score to "make the box" next year.
On behalf of V31DX-The Cuba Libre Contest Team, we would like to
congratulate those top finishers in the World Wide, especially PJ1B ,P40L
and P49T for an outstanding effort and all the others who make this
contest so competitive and a lot of fun.
Also, special thanks to the efforts of the contest committee, log
checkers, and CQ Magizine.....It's a brutal job and they can have it!
We hope to see you all in the World Wide.
Victor John Bill Peter.
V31VB V31ZZ V31DX V31UN
* Victor Burns - KI6IM / V31VB * CUBA LIBRE CONTEST CLUB *
* Iliff, Thorn & Company * V31DX *
* PH (619)-438-8950 FAX (619) 438-8925 * Home (619) 744-6836 *
* Snail Mail - 2386 Faraday Ave., Ste. 100 * FAX (619) 471-1428 *
* Carlsbad, CA 92008 * PO BOX 9794 *
* e_mail vburns at netcom.com * Rancho Santa Fe, CA 92067 *
>From mike.fulcher at aznetig.stat.com (Mike Fulcher) Thu Aug 25 04:35:07 1994
From: mike.fulcher at aznetig.stat.com (Mike Fulcher) (Mike Fulcher)
Date: Thu, 25 Aug 1994 03:35:07 GMT
Subject: Rohn Tower Basing
Message-ID: <940824211428166 at aznetig.stat.com>
-> Date: Wed, 24 Aug 1994 11:25:53 -0700 (PDT)
-> From: "Peter G. Smith" <n4zr at netcom.com>
-> Subject: Rohn Tower Basing
-> To: cq-contest at tgv.com
-> OK, guys, response to the lightning question was so good that I have
-> temerity to raise another one.
-> I have always seen guyed tower installations (Rohn 25 and 45) where t
-> first section was embedded in the concrete base, trued up, and then u
-> as the starting point for the tower. However, in reading the Rohn
-> catalogue I noticed that their parts lists for various heights and wi
-> loadings of guyed towers always assumed that a BPC25G concrete base p
-> would be used, which in turn sits down over a 3/4" pier pin" that is
-> only thing that is embedded in the concrete base.
-> Talked with Rohn today, and they tell me that they emphatically recom
-> this type of base arrangement over the embedded tower section because
-> "ultimate wind load" it is better for the tower to be free to pivot a
-> its base slightly, rather than to have all three legs firmly fixed.
-> claim this reduces the risk of broken welds, etc. that could result i
-> concealed weakening of the tower. Not incidentally, it looks to me a
-> it would be as easy or easier to embed the pier pin, as long as you c
-> get it relatively straight. For that matter, the drawings call for 1
-> slop between the base plate hole and the pier pin, so maybe pier pin
-> alignment isn't even really critical.
-> Does this square with usual practice out there, and I have seen a
-> minority of installations, or is there something wrong with the pier
-> pin/base plate set-up?
-> 73, Pete
-> N4ZR at netcom.com
I have used the pier pin method over the last 9 years with Rohn 45 and
Rohn 55 and have never experienced a problem. We do get severe winds
and thunderstorms here in the Phoenix area during the summer and the
towers have withstood all. Currently I have 2 100 foot Rohn 55 towers
up with beams spaced up and down each tower. The same goes for a 100
ft. Rohn 45 tower. Each uses the pier pin method. You just have to make
sure the base is flat and the pier pin is vertical when embedded in
concrete. It sure makes life easier when putting the towers up. Good
73 de Mike KC7V
>From GOLOMB JOHN <GOLOMB at LAKEHURST.NAVY.MIL> Thu Aug 25 12:48:55 1994
From: GOLOMB JOHN <GOLOMB at LAKEHURST.NAVY.MIL> (GOLOMB JOHN)
Date: Thu, 25 Aug 1994 07:48:55 -0400
Subject: DX Q's in NAQP? - Reply
Message-ID: <se5c4cca.006 at LAKEHURST.NAVY.MIL>
>If a non-NA station calls you during NAQP, can it be
>logged for a QSO point? Tnx Bob
Non North American QSO's in the NAQP count for points,
but not multipliers. Non-NA stations can only work NA
>From mbarts at vt.edu (Michael Barts) Thu Aug 25 03:29:49 1994
From: mbarts at vt.edu (Michael Barts) (Michael Barts)
Date: Thu, 25 Aug 1994 08:29:49 +0600
Subject: NAQP Score KB4NT
Another data point for the list Scott.
160 0 0
80 8 7
40 75 22
20 71 27
15 7 5
10 6 3
167 64 10,688
Operating time: 4:15
Things started out so well. 45 minutes into the contest I realized the time
and date on the computer were wrong. Guess its time to replace the clock
battery backup. 15 and 10 showed a little life early on but faded quickly.
20 was crowded so limited to S&P. Had some small runs on 40 late in the
afternoon before the BCI started but not many folks on and static was
terrible. Got to get a padded chair for the shack or else try that Buns of
Michael Barts mbarts at vt.edu
Research Engineer Amateur Radio: KB4NT
Litton Systems Poly-Scientific
Blacksburg, VA 24060
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