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Today's Topics:
1. Re: There's 'ground', and then there's 'ground' (Tom Rauch)
2. SteppIR installation (Martin Sole)
3. Re: There's 'ground', and then there's 'ground' (Frank Donovan)
4. Re: There's 'ground', and then there's 'ground' (Frank Donovan)
5. RE: SteppIR installation (Martin Sole)
6. RE: Moth Balls (GALE STEWARD)
----------------------------------------------------------------------
Message: 1
Date: Mon, 17 Jan 2005 04:06:40 -0500
From: "Tom Rauch" <w8ji@contesting.com>
Subject: Re: [TowerTalk] There's 'ground', and then there's 'ground'
To: <garyschafer@comcast.net>
Cc: towertalk@contesting.com
Message-ID: <004701c4fc73$ded5ab00$6601a8c0@akorn.net>
Content-Type: text/plain; charset="iso-8859-1"
How does the braid perform at 1 mhz?
I don't have any comparison data at 1 MHz Gary. Sorry.
------------------------------
Message: 2
Date: Mon, 17 Jan 2005 16:16:56 +0700
From: "Martin Sole" <msole@loxinfo.co.th>
Subject: [TowerTalk] SteppIR installation
To: <towertalk@contesting.com>
Message-ID: <20050117091656.5C5CE3BEE9@mailz1.loxinfo.co.th>
Content-Type: text/plain; charset="us-ascii"
Tomorrow myself, HS0ZED, and John, W2YR, will go to the shack of our good
friend Eddy, HS0/EA4BKA, to assemble and install his new 3 el SteppIR. We
have allowed ourselves a couple of days to complete the job staying
overnight in Pattaya which should be fun. I would appreciate any comments
or
suggestions from those that have already been through the process
regarding
anything we need to consider before starting. We will install an EF140 at
right angles, i.e. parallel to the boom of the SteppIR. Is it okay to
place
this just a few feet away give the orientation or do we need to be more
careful?
73
Martin - HS0ZED
------------------------------
Message: 3
Date: Mon, 17 Jan 2005 07:23:03 -0500
From: "Frank Donovan" <donovanf@erols.com>
Subject: Re: [TowerTalk] There's 'ground', and then there's 'ground'
To: <towertalk@contesting.com>
Message-ID: <015901c4fc8f$4c260720$6401a8c0@rock.gtegsc.com>
Content-Type: text/plain; charset="iso-8859-1"
Keith,
You should use braided strap only when RF grounding or
lightning protection is not required. Otherwise, use copper
strap, copper tubing or stranded or solid copper wire.
If you must use braid, use the 1 inch wide braid, and limit
its length to not more than one foot.
In the Amateur Electronic Supply catalog, 1.5 inch wide
copper strap is priced ($99.99/100 ft) about the same as
1 inch wide braid ($92.99). The 3 inch copper strap is
even better and is listed in the AES catalog at $139.99
per 100 feet.
73!
Frank
W3LPL
donovanf@erols.com
----- Original Message -----
From: Keith Dutson <kjdutson@earthlink.net>
To: <towertalk@contesting.com>
Sent: Monday, January 17, 2005 12:13 AM
Subject: RE: [TowerTalk] There's 'ground', and then there's 'ground'
Now this is the most plausible explanation seen so far. Basically it
seems
that there is no valid reason to have measured evidence if one follows
sound
engineering practice. Makes perfect sense to me. Think I will replace
the
braid with copper strap.
Tom, thanks for posting. And thanks to Frank for bringing up this issue.
As a side note, I went back to the Harger site which lists tinned copper
braid as one of their grounding strap options. All of their braid is
flat
and tightly woven (not the flattened coax shield found at most vendors),
very heavy gauge, and is bonded to special sandwich type lugs to keep
them
absolutely flat at each end. I am thinking this is a reasonable
alternative
to wide strap when one must have the flexibility.
Keith NM5G
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of Tom Rauch
Sent: Sunday, January 16, 2005 8:26 PM
To: keith@dutson.net; 'Frank Donovan'; towertalk@contesting.com
Subject: Re: [TowerTalk] There's 'ground', and then there's 'ground'
> However, it is empirical evidence that I am seeking. My
station ground
> system design is based on what I have found in ARRL and
other publications
> such as the technical documents provided by Polyphaser and
Harger. I found
> nothing published that spoke of the adverse effects caused
by using braided
> straps. Your posts are the only source.
Sometimes we can't easily find things that are commonly known or
understood
in engineering circles. Most engineers and many hobbyists understand skin
effect, and it only takes a moment to reason through this.
The problem with any conductor at high frequency is skin effect "pushes"
current to the outside. When the conductor is woven, current either has
to
flow from inward moving strand to a surface stand through pressure
contact
or suffer a path of greatly increased impedance if it follows the
original
strand inside the braid.
The typical clean copper braid with a basically parallel lay and minor
weave
has perhaps four times the resistance per unit length of a similar width
smooth surfaced conductor. Of course it varies with the braid
construction
and contact resistance between strands, but that is generally for better
braid that is clean with good pressure contact between strands.
In HF power amplifiers, I have found a good general rule of thumb is
this:
At 30 MHz is the clean braid from RG-8 cable has about the same current
carrying capacity as #14 or 16 tinned solid buss wire.
It's quite common to have braided leads of rather large size overheat and
fail even at just several amperes at radio frequencies.
Many construction standards prohibit braided straps in RF or lightning
paths
unless the connection absolutely must have braiding in order to withstand
flexing, and then the braid is often substantially oversized to make up
for
its reduced current capacity. It's my understanding NASA restricts use of
braiding, and I can cite many cases where braiding will either cause
excessive loss or actually fail in high current RF systems.
By the way, that permanent loss increase you see in coaxial cables that
have
been wet, even after they dry back out? It primarily comes from loss of
strand contact in the weave caused by the tarnishing of conductors.
If the Handbook tells readers braiding (especially braiding that might be
exposed to moisture) is a good idea in high frequency or lightning
grounds....they are giving bad advice.
73 Tom
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with
any
questions and ask for Sherman, W2FLA.
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_______________________________________________
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Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with
any
questions and ask for Sherman, W2FLA.
_______________________________________________
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------------------------------
Message: 4
Date: Mon, 17 Jan 2005 07:39:42 -0500
From: "Frank Donovan" <donovanf@erols.com>
Subject: Re: [TowerTalk] There's 'ground', and then there's 'ground'
To: <towertalk@contesting.com>
Message-ID: <017201c4fc91$9e58e560$6401a8c0@rock.gtegsc.com>
Content-Type: text/plain; charset="iso-8859-1"
Keith,
If you work as a professional in the industry, or if
you're interested in spending several hundred dollars,
purchase the EIA/TIA and IEEE grounding and bonding
standards that provide exactly the engineering foundation
information you are seeking. If you want to spend the
money, let it be known on the reflector and I'm sure
you will get the specifics.
Otherwise, I suggest you visit a commercial cell site, a
radio transmitter site, or a large computer facility in your
area.
Let us know how many braid straps you find. If you
find any, let us know how long they are.
73!
Frank
W3LPL
donovanf@erols.com
----- Original Message -----
From: Keith Dutson <kjdutson@earthlink.net>
To: <towertalk@contesting.com>
Sent: Sunday, January 16, 2005 3:59 PM
Subject: RE: [TowerTalk] There's 'ground', and then there's 'ground'
>Its been well proven that braided strap has far too much inductance to
>be
of any utility above 2 MHz.
OK. So where is the proof?
I am thinking any writing you can find is based on the use of braid that
of
poor manufacture or has corroded, or both. Poor or corroded braid can
act
like many very small wires to create substantial impedance. However,
well
constructed braid acts more like a solid bar of metal, but with the
flexibility required for many installations.
Keith NM5G
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of Frank Donovan
Sent: Sunday, January 16, 2005 10:35 AM
To: towertalk@contesting.com
Subject: Re: [TowerTalk] There's 'ground', and then there's 'ground'
Here's a clarification, pointed out by an attentive towertalkian:
My previous e-mail was not intended to refer to cables that use a braided
shield under a jacket. A tight jacket compresses the braid and it's a
very
effective RF conductor, provided that the braid is not corroded.
Rather, my comment was intended to apply to to the inappropriate use of
braided strap for RF grounding or lightning protection. Its been well
proven that braided strap has far too much inductance to be of any
utility
above 2 MHz.
So... Lets try again:
Discard all forms of "braided" strap.
Braid is something a girl does to her hair.
Braided strap is a poor RF conductor and it's a terrible conductor of
lightning energy.
Use braided strap only for DC and audio applications, its just an
inductor
for RF or lightning protection applications.
Here's an excellent reference from the many industry sources on this
topic:
http://members.cox.net/pc-usa/station/ground5.htm
73!
Frank
W3LPL
donovanf@erols.com
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with
any
questions and ask for Sherman, W2FLA.
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with
any
questions and ask for Sherman, W2FLA.
_______________________________________________
TowerTalk mailing list
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http://lists.contesting.com/mailman/listinfo/towertalk
------------------------------
Message: 5
Date: Mon, 17 Jan 2005 19:50:59 +0700
From: "Martin Sole" <msole@loxinfo.co.th>
Subject: RE: [TowerTalk] SteppIR installation
To: "'Pete Smith'" <n4zr@contesting.com>, <towertalk@contesting.com>
Message-ID: <20050117125109.BE0637F872@mailz2.loxinfo.co.th>
Content-Type: text/plain; charset="us-ascii"
Thanks Pete, that is what we figured and we will be putting the EF140
perpendicular to the SteppIR elements. In this configuration do you think
6
feet is the minimum?
73
Martin - HS0ZED
-----Original Message-----
From: Pete Smith [mailto:n4zr@contesting.com]
Sent: 17 January 2005 18:36
To: Martin Sole
Subject: Re: [TowerTalk] SteppIR installation
I have an EF-240S that is 6 feet above a tribander, and interaction was
severe until I turned it perpendicular. That suggests to me that much
less
than 6 feet would probably be asking for trouble on 15 meters.
73, Pete N4ZR
At 04:16 AM 1/17/2005, you wrote:
Tomorrow myself, HS0ZED, and John, W2YR, will go to the shack of our
good friend Eddy, HS0/EA4BKA, to assemble and install his new 3 el
SteppIR. We have allowed ourselves a couple of days to complete the job
staying overnight in Pattaya which should be fun. I would appreciate
any comments or suggestions from those that have already been through
the process regarding anything we need to consider before starting. We
will install an EF140 at right angles, i.e. parallel to the boom of the
SteppIR. Is it okay to place this just a few feet away give the
orientation or do we need to be more careful?
73
Martin - HS0ZED
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with
any questions and ask for Sherman, W2FLA.
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
------------------------------
Message: 6
Date: Mon, 17 Jan 2005 05:09:54 -0800 (PST)
From: GALE STEWARD <k3nd@yahoo.com>
Subject: RE: [TowerTalk] Moth Balls
To: towertalk reflector <towertalk@contesting.com>
Message-ID: <20050117130954.59343.qmail@web50701.mail.yahoo.com>
Content-Type: text/plain; charset=us-ascii
This is true. However, I've found it takes several
years when they are inside a relatively airtight
enclosure. I check them during normal equipoment
maintance.
73, Stew K3ND
--- "Al, N6TA" <n6ta@arrl.net> wrote:
Those of you planning on the mothball approach, be
aware that they will
eventually wither away and leave you unprotected.
Al
N6TA
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com]On Behalf
Of RICHARD BOYD
Sent: Friday, January 14, 2005 06:26
To: towertalk reflector; ABowenN4OO
Subject: Re: [TowerTalk] Moth Balls
I will be implementing this tip in all the places I
will have that will be
like this. My plan is to put a utility box (I have
13 of the utility
company-type light green ones) at the base of each
tower as a junction for
coax coming down the tower and the coax to the shack
-- for ground, etc.
Just sitting around, these boxes clearly are an
attractive nest site for
wasps. I hope the moth balls will keep them all
out.
On lady bugs, I suppose half of them are "gentleman
bugs." And maybe
they're not "gentlemen." We have a lot of ladybugs
here, in the house. I
think they are coming in through the bathroom vents.
I didn't realize that
they "over-winter," but apparently they do, seeking
cozy hideaways, with 10,
20 or more huddled together in corners of the
ceiling. Since they are
apparently harmless and, in fact, are beneficial in
the growing season
because they eat aphids, which in turn eat roses,
and are more charming than
most insects, I'm not too worried about them.
73 - Rich, KE3Q
----- Original Message -----
From: "ABowenN4OO" <abowen@nettally.com>
To: <towertalk@contesting.com>>
Sent: Friday, January 14, 2005 7:05 AM
Subject: [TowerTalk] Moth Balls
> I was about to publish a note similar to K3ND's,
regarding insects and
> moth
> bolls. I opened my relay box out on the tower and
found stacks of lady
> bugs
> doing unlady like things inside the box. In
addition, there were a number
> of wasp clusters and spider webs.
>
> I put 5 moth balls in a small diameter glass jar
and taped it inside the
> relay box (12 X 18"). No more insects. I have done
the same for my remote
> Beverage boxes which are loved by spiders, but a
single ball will do for
> those.
>
> I am not sure about the composition but think the
major ingredient is
> naptha. I put the moth balls in a glass jar
because I was not sure of the
> effect of naptha on the various plastics. Plastic
pill containers should
> also work for a time also per K3ND. I suspect the
balls will evaporate
> with
> time and require replacement.
>
> I also intend on dropping one or 2 on fire ant
hills and see if I can get
> them to move.
>
> INK N4OO
> ===========================================
> At 05:42 AM 1/13/2005 -0800, GALE STEWARD wrote:
>
> >Years ago one of the OTs mentioned that fact the
he
> >used moth balls to keep insects out of outdoor
> >enclosures. I have a matching network for my
80/160
> >vertical. See:
>
>
> _______________________________________________
>
> See: http://www.mscomputer.com for "Self
Supporting Towers", "Wireless
> Weather Stations", and lot's more. Call Toll
Free, 1-800-333-9041 with
> any questions and ask for Sherman, W2FLA.
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
>
http://lists.contesting.com/mailman/listinfo/towertalk
>
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting
Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free,
1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting
Towers", "Wireless Weather Stations", and lot's
more. Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
_______________________________________________
TowerTalk mailing list
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http://lists.contesting.com/mailman/listinfo/towertalk
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End of TowerTalk Digest, Vol 25, Issue 87
*****************************************