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Subject: AA6KX/county
From: paul@paccomm.com (paul@paccomm.com)
Date: Fri Jun 23 08:31:02 1995
Maybe by the end of FD California will have moved enough to
put him in the next county anyway.......  <(:-(  

Paul Evans, W4/G4BKI   paul@paccomm.com  +1 (813) 874-2980     .   
Fax:+1 (813) 872-8696 Views expressed here are not necessarily |\
those of PacComm. I don't surf the internet, I SAIL IT!       /| \         
Captain of S/V "Spindrift", Dunedin, FL.                     / |--\
Tall rig (58'), Winged Keel (4' 2"), full batten main       /  |   \
PacComm Packet Radio Systems,Inc.,                         /   |----\
4413 N. Hesperides St., Tampa, FL 33614-7618              /    |     \  

>From wrt@eskimo.com (Bill Turner  W7LZP)  Fri Jun 23 13:20:42 1995
From: wrt@eskimo.com (Bill Turner  W7LZP) (Bill Turner  W7LZP)
Subject: Which vertical
Message-ID: <199506231221.AA02539@mail.eskimo.com>

At 08:35 AM 6/22/95 -0500, John D. Allen wrote:
>Doesn't it matter what band you are considering?
>(Pardon me if I don't remember the start of this thread)
>I agree completely with Bill's comments below if you are talking about
>40 M and up, provided you have a support for a dipole/inverted V.
>But, it seems to me that 80 is dependant on the height of support you can
>and 160M more so.  I know that it also depends (on 160 especially) on band
>conditions - there are times when the angle is higher and dipoles do well and
>times on 160 when only the guys with vertical antennas (Inv L's etc.)
>get out.
>Note that a 160 dipole at 60' is the same part of a wavelength above ground
>as a 10M dipole at 4 feet.  I know from experience that a 160 dipole at
>60' has trouble working long haul DX, although at the bottom of the sunspot
>cycle almost any antenna can get out.
>73, John, K1FWF
Absolutely right, John.  During the last CQ 160 Meter SSB contest I was
running 1 kw to my 50 foot vertical which has an "average" set of radials
for a city lot -- 25 of them, averaging about 50 feet, with a few longer
ones.  It was very carefully resonated and matched and works well for what
it is.  However, there was a VE7 about 150 miles north of me who was running
the same power, but to a full size inverted vee with the apex at 120 feet.
Stations on the east coast which he would get on the first call took me two
or three or four to get.  I saw this over and over, and it was a real
eye-opener for me.  The vertical with its theoretically lower angle of
radiation just wasn't cutting it.

As you pointed out, 120 feet on 160 is like 8 feet on 10 meters.  Nobody in
their right mind would put up a 10 meter antenna at 8 feet, but you do what
you can do and hope for the best.  

73, Bill  W7LZP

>From Peter G. Smith" <n4zr@netcom.com  Fri Jun 23 13:37:06 1995
From: Peter G. Smith" <n4zr@netcom.com (Peter G. Smith)
Subject: Sources for "Grounds"...
Message-ID: <Pine.3.89.9506230521.A10817-0100000@netcom20>

Polyphaser direct offers a 10 percent discount for hams!  I ordered it 
yesterday and believe the price, exclusive of S&H, was $20.65.  They take 
Visa and Mastercard.

73, Pete                                       
"Better, faster,cheaper -- choose any two"
"No no no -- it's WEST Virginia"

>From jallen@vhfcom.com (John D. Allen)  Fri Jun 23 14:42:48 1995
From: jallen@vhfcom.com (John D. Allen) (John D. Allen)
Subject: exploding bases
Message-ID: <199506231242.IAA07415@nic.iii.net>

One more opinion - I believe that it is possible, if the primary
current path for a direct strike is through the poured concrete base of the
tower, for damage to the concrete to occur.

My 110 ft tower was hit in 1991.  The top 70 feet had been installed 
with conductive grease (NoAlox) between the sections, not for the conductivity,
but to make it possible to dis-assemble later.
The bottom 30 feet did not have no-alox.

The section joints without no-alox and the clamps that connected the
copper ground wires to the tower all had their bolts loosened by the strike
(as much as several turns)  The sections with no-alox were tight.

If you put 10,000 to 100,000 amps through a steel tube, it is going to get hot.
When it gets hot, it expands.  Apparently the nuts just unscrew.
I am told it was common practice in the midwest to re-tighten windmill
tower bolts every year.

If your tower section etc. expands like above in concrete, some damage could be 
done.  But, the current is going to divide according to the impedance of the

If your tower's best ground is through the base, that is where the current is
going to go.  This implies steel protruding from the concrete underground.
BUT, if there is metal protruding out of the concrete underground,
it will corrode - this is why you are supposed to keep re-bar several inches
inside the concrete - see the Rohn documentation.

If there is no metal protruding through the concrete, then the impedance 
to ground through the concrete is going to be higher than that through
several large gauge wires or copper strap.  Conductivity is relative, and 
though concrete may conduct, it is far higher resistivity than copper. 

John, K1FWF  jallen@vhfcom.com

> "Stankiewicz, Warren,  NF1J" <wstankiewi@arrl.org> writes:
> > 
> > I wonder though--if lightning hit a recently poured base, where there was 
> > still a fair amount of water involved, couldn't that water turn into steam 
> > and then cause the "exploding base" phenomenon?
> > 
> Gee, I would hope that whoever was installing a tower would have the 
> sense to wait until the base solidified before building up the tower!
> According to the Polyphaser book (which should be mandatory reading for 
> anyone with a tower), the exploding base theory just doesn't hold water 
> (pun intended). Also, concrete absorbs water quickly and gives it up 
> slowly. Witha ll the lime and other minerals in the concrete, it is a 
> GOOD conductor when moist. Of course, if you live in the desert, this 
> doesn't apply.
> 73

John D. Allen, jallen@vhfcom.com

>From Derrick Belbas <dbelbas@csdxp01.City.Winnipeg.MB.CA>  Fri Jun 23 14:55:28 
From: Derrick Belbas <dbelbas@csdxp01.City.Winnipeg.MB.CA> (Derrick Belbas)
Subject: my gloves don't fit -- VV's on 40m
Message-ID: <sfea73f5.088@City.Winnipeg.MB.CA>

Contrary to rumour, I emphatically deny that I have ever sent more than a
few dozen V's on 7002 kHz.  I usually toss in a dit (E) here or there.

That's my story and I'm sticking to it.


Derrick  VE4VV

>From Lau, Zack,  KH6CP" <zlau@arrl.org  Fri Jun 23 14:30:00 1995
From: Lau, Zack,  KH6CP" <zlau@arrl.org (Lau, Zack,  KH6CP)
Subject: Which vertical
Message-ID: <2FEAC279@arrl.org>

Bill W7LZP wrote:.
>As you pointed out, 120 feet on 160 is like 8 feet on 10 meters.  Nobody in
>their right mind would put up a 10 meter antenna at 8 feet, but you do what
>you can do and hope for the best.

I have gotten great results using a 15 meter dipole up only 10 ft. over flat 

ground.  Of course the ground conductivity was superb--the location was
Sand Island--a little island of the Coast of Oahu, both of which are in the
City and County of Honolulu.  I remember working lots of 3000 to 5000 mile
SSB contacts with 2 watts.    The available trees weren't very high.

KH6JNP used to do nearly the same thing--rather than try and run something
from his apartment, he used to run "mobile" and parked very close to the 
He had no trouble at all maintaining a schedule with his wife back in Orange
country, CA.  How close did he park?  Well, someone grabbed his parking spot
one day.  Unfortunately, someone else had an auto accident and pushed the
car into the water...

I haven't tried it myself, but I'm pretty sure the new terrain analysis 
will show you can also compensate for low antenna height with favorable
ground slope.

Zack zlau@arrl.org

>From Peter G. Smith" <n4zr@netcom.com  Fri Jun 23 14:46:59 1995
From: Peter G. Smith" <n4zr@netcom.com (Peter G. Smith)
Subject: Which vertical
Message-ID: <Pine.3.89.9506230628.A10817-0100000@netcom20>

Zack's right, but you don't need the new terrain software to understand the 
effect of a sloping foreground on radiation angle for a given height.  
There is an excellent explanation of this phenomenon in Dave Leeson's 
"Physical Design of Yagi Antennas."

73, Pete                                       
"Better, faster,cheaper -- choose any two"
"No no no -- it's WEST Virginia"

>From barry@w2up.wells.com (barry)  Fri Jun 23 14:26:10 1995
From: barry@w2up.wells.com (barry) (barry)
Subject: exploding bases
Message-ID: <BuH67c1w165w@w2up.wells.com>

jallen@vhfcom.com (John D. Allen) writes:

> BUT, if there is metal protruding out of the concrete underground,
> it will corrode - this is why you are supposed to keep re-bar several inches
> inside the concrete - see the Rohn documentation.

I'm not so sure this is the reason. As mentioned previously, concrete is 
full of moisture, therefore would corrode insdie as well as outside the 
concrete, unless the alkaline pH keeps it from oxidizing. I don't know 
the answer to this one - any construction-types out there?

I know that in my poured-concrete basement, there are reinforcing bars 
throughout the width (10 inches, maybe) that I believe helped support the 
forms. After pouring, these protruded a couple of inches inside and out, 
and were cut off flush with the concrete.

>From Peter G. Smith" <n4zr@netcom.com  Fri Jun 23 16:15:22 1995
From: Peter G. Smith" <n4zr@netcom.com (Peter G. Smith)
Subject: exploding bases
Message-ID: <Pine.3.89.9506230821.A28729-0100000@netcom20>

For what it's worth, the Rohn spec provides that any rebars in a tower
base should be embedded at least 3 inches under the surface of the
concrete.  However, I also understand that if you embed a tower section in
the concrete, it is critically important to make sure that the legs
protrude from the base into a bed of gravel, to avoid the entrapment of
water inside the tower legs.  A friend of mine had to abandon an embedded
base when the entrapped water level rose above the concrete, the water
froze, and the tower legs split open.

73, Pete                                       
"Better, faster,cheaper -- choose any two"
"No no no -- it's WEST Virginia"

>From BILL FISHER" <BFISHER@CONCEN.COM  Fri Jun 23 11:44:47 1995
Subject: TA by K6STI
Message-ID: <9505238039.AA803929487@concen.concen.com>

     QCAO review of TA by K6STI
     QCAO = Quarter Century Appliance Operator (K7SS founder)
     I just got my copy of TA (Terrain Analyzer) by K6STI.  This program 
     analyses antennas (you pick the antenna) over a specific terrain (you 
     pick the terrain).  
     I'm just starting to play with it, but it is quite interesting to see 
     the effects of ground slope on antennas.  The program comes with quite 
     a few terrain files of famous contesters.  BTW:  K5ZD looks to be the 
     clear winner to Europe for best terrain.  You have to see W6QHS's 
     plots to believe them!
     In my case I have confirmed that higher is not always better on a 
     hill.  On 10 meters anything over 30 feet falls apart.  It begins to 
     exhibit high angle lobes and the nice fat wide ones at lower angles 
     disappear.  Just a narrow VERY low angle lobe and many higher angle 
     lobes when above 30 feet.
     I would suggest this program for anyone with highly irregular terrain. 
     It might save some time in deciding what height is best.  For flat 
     landers, I believe everything published on stacking distance and 
     height has been geared to you anyway.  
     Maybe N6ND can give a more detailed/technical review for us?  If Ya'll 
     are interested.
     Bill Fisher, KM9P

>From Terry Conboy <tconboy@Gateway.Uswnvg.COM>  Fri Jun 23 16:53:32 1995
From: Terry Conboy <tconboy@Gateway.Uswnvg.COM> (Terry Conboy)
Message-ID: <9506231553.AA03684@nv2410.uswnvg.com>

I've been passing most of the messages from the "LIGHTNING" thread to our 
company grounding expert, Jeremy, WA7YGB.  He had a few interesting comments
which I am passing along.  He is not a list subscriber, so e-mail him
directly at the address below with comments or questions.



I'm U S WEST Cellular's "grounding guru" and have been following the
exploding concrete situation with interest.  Haven't been able to write 'til
now due to lack of time.  

I'm really impressed with the response below, so I copied it to add value to
it via some comments.  Steve did a fabulous job and saved me some typing.

Some things to note:

1.  Lightning is like a drug addict.  It only wants one thing - to get to
ground.  Don't get in its way or it will "blow you away."  Just give it what
it wants.  Help it get to ground via the most direct route and you will
minimize any damage.  (Our cell sites sustain direct hits with NO damage,
except if it comes in on the phone lines, where the ONEAC protector will blow.)

2.  Ufer grounds do work well, as Steve points out below.  The 1993 National
Electrical Code even shows an example of how to install one (they call it a
"concrete encased electrode.")  There is one instance of concrete damage
that can occur with a Ufer ground, however, of which you should be aware.  

If the wire carrying the lightning current passes within a few inches (less
than 6) of a rebar, there can be an arc to the rebar which will carbonize
the concrete in that area and weaken it.  The solution is to bond the wire
to the rebar (using UL 467 listed crimp connectors or Cadwelds), or keep
them over 6 inches apart.  

3.  Steve is correct that (except in Death Valley) in-the-ground concrete
deeper than 30 inches is usually moist and surprisingly conductive, but not
as good as metal.  This makes the concrete one of the ground rods, like it
or not.  Field data says that there hasn't been a problem with the concrete
exploding, probably due to the mass.  However, if a lightning carrying
conductor comes near a corner or edge, people have observed cracking in the
concrete.  Maintain a 3" distance.

I do know of a situation where lightning punched a hole in concrete.

Rohn tower company makes a concrete cellular monopole which uses stressed
steel wires to hold it together.  The factory rep told me they found that if
lightning got into the steel strands at the top of the tower, it traveled
down the strands and tried to get out at ground level.  It punched a fist
size hole through the concrete trying to get to ground.  The (dry) concrete
of the monopole's skin was in the way and the lightning simply pushed it
aside.  Rohn plans to solve  this by giving the lightning an alternate way
to get to ground.  They will attach two #2 copper wires along the outside of
the concrete pole to couple the lightning energy to the ground ring cellular
companies install around a tower.

4.  Be impressed with the power of lightning.  It can do a lot of damage.
To paraphrase an atmospheric physicist from Sandia Labs I once met,
"lightning causes the most damage if high impedance things get in its way.
A water tank will shrug off the strike while a tree explodes."  I've always
remembered that.

5.  Lightning current, which ranges from 18,000 Amps to 270,000 Amps, is a
current that generates a magnetic field, which in turn induces currents in
nearby conductors.  One of those secondary currents could cause some damage
to your sensitive equipment, but doesn't have to.  You can prevent injury
by avoiding ground loops.

Jeremy Donimirski WA7YGB           E-mail: jdonimi@uswnvg.com
U S WEST NewVector Group, Inc.     Office: (206) 450-8395
Bellevue, Washington               Fax:    (206) 450-8399
    "Speaking for myself and not for my employer"

Previously, Steve KC2X (ssacco@mcimail.com) wrote:
>I live in Central Florida, which is an area known as the "Lightning Capital
>of the United States".  We experience >100 days/year of lighting activity. 
>Lightning bolts in Central Florida are THREE times more powerful than your
>"average" bolt, and also carry two to three times the current ofyour
>average, every day strike.  Because of this, lightning protection is a
>subject on which I've done a fair amount of research.  Having done this
>research (which, by the way, was neither difficult nor boring), I find it
>very difficult to deal with some of the ridiculous "theories" on lighting
>protection I've heard and seen.
> From the messages I've read - and I've just plowed through them all -
>there's been only a few excellent sugestions.  One of them was  to purchase
>the PolyPhaser book "The 'Grounds' for Lightning and EMP Protection", by
>Roger R. Block.  Anyone interested in this topic - and that should be
>EVERYONE save a few of the West Coast USA types - should know the basic
>information (as opposed to the formulas, etc) in this book by memory! 
>Think about it - is it REALLY a matter of "life and death" if you choose
>between an FT-1000 and an IC-775 for your next rig?   No.  
>You can't say the same thing about lightning protection!
>For all of the thousands of dollars many of us spend on radios, antennas,
>$1,300 Geochron clocks, Pentuim PCs,  and other "essential" widgets, it's
>interesting to speculate why ANYONE would be willing to let twenty-five
>bucks get between them and continued ignorance on such an important
>With respect to the "exploding base" myth, Mr. Block has the following to
>say: (he is discussing "Ufer" grounds):
> "One of the most important tests performed was under acutal lightning
> conditions.  The test was to see if the Ufer ground would turn the water
> inside the concrete into steam and blow the foundation apart.  Results
> indicated that if the Ufer wire were long (20-feet minimum) and kept
> approximately 3-inches from the bottom and sides of the concrete, no such
> problems would occur. (In my many years of experience, I have only seen one
> tower base with cracks that could be considered as lightning induced....)"
>With respect to the "Don't ground anything and lighting will not hit it"
>argument, Mr. Block says: 
> "One of the best sayings is really not a myth at all "A gounded tower is
> more likely to be hit.  As we say in the graph in chapter one, the taller
> an object the more frequently it's struck.  Why ground a tower if it means
> that it is more apt to be hit?  Look at it from the reverse point of view -
> if a tower that isn't grounded is hit, who would have control of the
> situation, the tower owner or Mother Nature?  With a properly grounded
> tower, the owner has control.  The whole concept of lightning protection is
> to control and direct the lightning surge energy so that it does the least
> amount of harm or damage."  
>So, proper lighting protection is really a matter of CONTROL.  Do you want
>to ALLOW yourself to be a victim, or do you, to the best of your ability, 
>manage the situation to afford yourself the safest conditions possible?
>Clearly, the idea of NOT grounding your station seems a bit silly when cast
>in this light.  NOTHING is a perfect insulator!  Even a Fibreglas pole will
>conduct electricity if it's covered with rain water (witness the many
>VHF/UHF verticals blasted off the tops of towers every year), so pretending
>that an ungrounded tower will not be struck is sheer fantasy.
>Hopefully, the above quoted material didn't violate too many copyright
>laws. I would submit to you that that information ALONE is worth $25! 
>Another tip is to make sure that all of your grounds are at the same
>potential, including your house ground.  This means connecting ALL of your
>ground points together.  I have four towers; three of them 100' or greater
>in height.  They are the tallest things around for miles and miles.  They
>ALL have ground radials with ground rods every 16', and all four towers'
>grounds are tied to a common grounding point just outside the shack (where
>the lightning arrestors are) and also to the house ground.  I've used over
>85  8' ground rods, and  buried more ground wire than I even want to think
>It's the price you pay for not being a victim.
>Oh, does anyone want to know why those wire-brush thingies sold as
>"lightning protection" don't work?  What about the "ground radial circle"
>myth?  What's the significance of 150 feet with respect to lightning
>strikes?  Get the book.
>Steve KC2X
>Narcoosee, Florida
Terry Conboy  tconboy@uswnvg.com  vm:206-450-8388  fax:206-450-8399
Does not speak for U S WEST, AirTouch, TomCom, or PCS PrimeCo.

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