Kenwood web page

Tue Sep 19 08:32:32 EDT 1995

Has anyone had success getting to the new stuff in the Kenwood page?
I can't seem to access their latest newsletter (July/Aug) or the info
on the TS-870s (which sounds like a great CONTEST radio)

(I figure this message is at least as trivial as THE name controversy)
********************************************************************
*  W8CAR pems_st_dk at noeca.ohio.gov                                 * 
*  Dan Kovatch                                                     *
*  Antennas are the key - BUT an ALPHA sure doesn't hurt!          *
********************************************************************

>From Tony Brock-Fisher <fisher at hp-and2.an.hp.com>  Tue Sep 19 14:19:36 1995
From: Tony Brock-Fisher <fisher at hp-and2.an.hp.com> (Tony Brock-Fisher)
Date: Tue, 19 Sep 1995 09:19:36 -0400
Subject: Freestanding Rohn 25
Message-ID: <9509191319.AA07508 at hp-and2.an.hp.com>

In response to queries about freestanding Rohn 25:

I just completed the installation of a bracketed 50 foot tower of Rohn 25.
In accordance with local zoning requirements, I had the whole thing 
engineered by a professional structural engineer. My engineer is a ham
and has 5 towers of his own. His analysis resulted in the following
specs:

           50 foot Rohn 25; bracketed at 30 feet.
           6 square feet windload max (Cushcraft A4).
           85 MPH plus 1/4 inch radial ice.
           1" feedline on one tower leg.

The limiting factor was the bending stress on the tower section
at the bracket. BTW, at this load, the sideways force on the house
bracket was 1,111 lbs! You should see the bracing inside my attic!

I think from this you could assume that 20 feet is the max freestanding
height for Rohn 25 loaded as above.

-Tony, K1KP, fisher at hp-and.an.hp.com

>From broz at csn.net (John Brosnahan)  Tue Sep 19 15:38:46 1995
From: broz at csn.net (John Brosnahan) (John Brosnahan)
Date: Tue, 19 Sep 1995 08:38:46 -0600
Subject: Rohn 25 capacity?
Message-ID: <199509191438.IAA03062 at uucp-1.csn.net>

RE:  w7ni at teleport.com (Stan Griffiths)

Stan, an excellent treastise on Rohn specmanship that agrees with
my 30 years of experience installing Rohn towers from the tropics to
 the arctic.  If all Rohn towers decided to believe their own specs, 99% 
of the big signals on the bands would disappear overnight. 

The most common failures that I have seen have come from two sources, 
1) improper or inadequate guying  2) concentrated torque forces.

Improper and inadequate guying includes undersized concrete guy pads,
improper or underrated guying strand, incorrect termination of the guy
wire to the tower, and poor quality or fewer than recommended wire 
rope clips.  The concentrated torque forces come from installations that 
include large side mount antennas with brackets that place all of the 
stresses on one or two weld points.  Rohn 45 legs are relatively thin wall 
tubing and the welding process results in situations where the force may 
break a zig-zag from a leg in such a way that the weld does not fail but a 
3/4 to 1 inch section of the leg is pulled out.

If the guying is adequate for the wind load then the failures invariably
come from
torsional failure of the tower due to large rotating masses with long torque
arms. 
The regular torque assemblies from Rohn help (a little) to transfer the
torque to 
the guys, but the large triangle guy mount with six guys is much better for
large 
loads.  

Another way to help the situation is to separate the antenna torque axis
from the 
center axis of the tower.  This can be accomplished by mounting the antenna, 
mast, and rotator outside of the tower on one face.  Now the antenna torque no 
longer is on the same axis as the tower and the forces from rotating the
antenna 
are no longer only rotational forces on the tower and guy structure but are now
a combination of rotational and translational forces. 

Torque forces from a large antenna are transferred to the tower at the
rotator mounting
point, which then transfers the forces to the guy point through the tower.
If the
rotator is 10 ft below the top of the tower and the guys are at the top,
then these forces
are transferred through that 10 ft of tower.  For large torque loads it is
always a good
idea to install a set of torque resisting guys at the rotator mouting point.

Common sense is a valued commodity but it is often disregarded in the interest 
of haste or cost cutting.  And, although I have seen many amateur installations
that I felt were inadequate or unsafe, the professional sites have a significant
number of problems as well.  One can learn a lot by seeing what has stayed up
for a number of years in the area.  Become a student of tower installations and
review every step with an attempt to anticipate the weak links and upgrade them.

Of the three deaths in Colorado (that I am aware of) over the last couple of
decades,
all involved removing the last set of guys during a tower removal without
adequately
determining if the base was adequate to self support the tower up to the first
guy point.  When removing a tower after many years, the details of the
installation
may not be clearly known, and there is always the possibility of a much
weaker tower 
at the point where it enters the concrete from a combination of rust from water
inside the legs and chemical reaction with the concrete.  Temporary guys are a
bit of a nuisance, but so are funerals!

Keep up the good work, Stan.

73  John  W0UN

>From mats.persson at mbox2.swipnet.se (Mats Persson)  Tue Sep 19 19:22:43 1995
From: mats.persson at mbox2.swipnet.se (Mats Persson) (Mats Persson)
Date: Tue, 19 Sep 1995 20:22:43 +0200
Subject: TF4 Flatey Island activated
Message-ID: <199509191822.UAA17258 at mailbox.swip.net>

Hi OM,

Tomorrow morning Nils SM6CAS and me Mats SM7PKK will fly to Iceland. On 
friday this week we will 
start activating Flatey EU-168. The main purpose is to take part in the SAC 
Contest SSB part as a multi single station. I intend though to be active as 
much as I can on CW before the contest (none or very limited SSB operation 
will be done before the contest)

Calls we will use are                   TF4/SM7PKK on CW
                                                 TF4/SM6CAS on SSB in SAC 
contest (unless we manage a real TF call)

QSL routes are  TF4/SM7PKK via SM7PKK
                        TF4/SM6CAS via SM6CAS

Hope to see you in the logs 

73 de Mats SM7PKK

>From n2ic at drmail.dr.att.com (LondonSM)  Tue Sep 19 19:15:10 1995
From: n2ic at drmail.dr.att.com (LondonSM) (LondonSM)
Date: Tue, 19 Sep 1995 12:15:10 -0600
Subject: 40 Meter EU (and JA !)
Message-ID: <9509191215.ZM21125 at dr.att.com>

It's hard to read K3ZO's predictions about 40 meters/EU for the upcoming
contest season without breaking into a smile !

Those of us who are geographically challenged have been experiencing the "40
meter EU MUF dropout"  since early 1993.  By the time CQWW CW rolls around, 40
meters has been open to EU for only an hour just before local sunset
(2230Z-2330Z).  Sometimes (but not always) we get a fair opening around
0700Z-0800Z to western EU.  From 01Z-06Z, all we hear are Africans, Carrib, and
SA.

The situation from here to JA is only slightly better.  A good JA opening from
0730Z-0830Z, followed by 3-4 hours of listening to W6GO and N6DX run JA that we
barely hear on backscatter to the SW, followed by 1.5 hours of good JA
(1300Z-1430Z).

Gotta run and work on those 80 meter antennas !

Steve London, N2IC/0
n2ic at dr.att.com

>From w7ni at teleport.com (Stan Griffiths)  Tue Sep 19 20:19:54 1995
From: w7ni at teleport.com (Stan Griffiths) (Stan Griffiths)
Date: Tue, 19 Sep 1995 12:19:54 -0700
Subject: Rohn 25 capacity?
Message-ID: <199509191919.MAA18918 at desiree.teleport.com>

John, W0UN writes:

>Of the three deaths in Colorado (that I am aware of) over the last couple of
>decades,
>all involved removing the last set of guys during a tower removal without
>adequately
>determining if the base was adequate to self support the tower up to the first
>guy point.  When removing a tower after many years, the details of the
>installation
>may not be clearly known, and there is always the possibility of a much
>weaker tower 
>at the point where it enters the concrete from a combination of rust from water
>inside the legs and chemical reaction with the concrete.  Temporary guys are a
>bit of a nuisance, but so are funerals!
>

How right you are, John.  None of my 4 towers (3 guyed, and one bracketed)
have concrete bases designed to hold the tower up without guys.  When I
installed them, I used temporary guys and they must come down the same way.
Problem is, I probably won't be here to mention that to the poor soul who
takes on the job.  I will mention it to my wife, however, and hope she
remembers to pass it on or at least keep her liability insurance in force!

What we need is a good way to permanently label the tower itself to remind
the person who takes it down to use temporary guys.  How can we attach such
a label and what would it look like to be sure and catch the eye of the
person who needs to know?  The label should go on the tower the same day it
is put up and stay there until it comes down.  You never know when you might
meet your maker on the highway coming home from work so you should be as
prepared as possible.  On the other hand, the label has to be good enough to
last for 50 years since it is quite possible for a tower to be in place that
long, maybe longer.

Stan     W7NI at teleport.com

>From sellington" <sellington at mail.ssec.wisc.edu  Tue Sep 19 20:42:56 1995
From: sellington" <sellington at mail.ssec.wisc.edu (sellington)
Date: 19 Sep 1995 14:42:56 -0500
Subject: Rohn 25 capacity?
Message-ID: <n1400600667.58335 at mail.ssec.wisc.edu>

Calculation of guy wire stress, etc., is quite simple.   Unfortunately,
the liability concerns probably preclude anyone distributing a software
package for mechanical tower design. For the same reason, of  course, you'll
never find a chapter in the ARRL Antenna Book on mechanical tower system 
design.  The really unfortunate result is that lots of folks put up towers
without the benefit of this kind of information, and some of them are bound to
be unsafe.

Scott   K9MA
sellington at ssec.wisc.edu

>From Tom Morrison <t.morrison at liant.com>  Tue Sep 19 16:03:00 1995
From: Tom Morrison <t.morrison at liant.com> (Tom Morrison)
Date: Tue, 19 Sep 1995 15:03:00
Subject: Rohn 25 capacity?
Message-ID: <9509192002.AA06096 at rmc.liant.com>

Stan  W7NI writes:

> What we need is a good way to permanently label the tower itself to remind
> the person who takes it down to use temporary guys. ...deleted...  the label
> has to be good enough to last for 50 years since it is quite possible for
> a tower to be in place that long, maybe longer.

An excellent point, especially in today's legal environment.

1.  You should have anti-climb plates around the bottom of the towers
     anyway, to which you can attach

2.  An etched (or routed) sign of a suitable material.

Since the persons removing the tower must remove the anti-climb device
that should do the job.

Tom K5TM

Tom Morrison, T.Morrison at liant.com
Relativity (div. Liant Software)
512-719-7019  FAX:512-719-7070  WWW: http://www.liant.com/