Towertalk
[Top] [All Lists]

[TowerTalk] 16om L

To: towertalk@contesting.com
Subject: [TowerTalk] 16om L
From: Jwpjj@aol.com
Date: Fri, 5 Dec 2008 12:08:04 EST
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
This was a subject I presented a few months ago with great response here on  
the reflector and privately. My L is about 70' vertical and 62' horizontal, 
fed  with LMR 400 through a 2:1 unun, 1 ground rod approx. 5' feet into the 
hardest  ground you will find east of the Mississippi. I started out with 4 
radials,  wasn't bad, about 1.5 at 1850, check the MFJ and the z was wacky, so 
after 
 getting some tips, I started adding radials, everytime I added a radial I 
check  the vsr , it was going up and my z was going down. Total radials up to 
date, 24  @ 133'. I did add more, but nothing changed so I left it at 24 
radials. At 1800  1.6 at 1850 1.4 and at 1900 1.7.  This ant plays very well, 
everything  I hear on the receive loops, I can work and its been a blast to be 
back 
on 160.  Enjoy the DX chase on this band its a challenge but a lot of great fun 
 
John 
ND1X.
 

 
In a message dated 12/4/2008 11:19:37 P.M. Eastern Standard Time,  
towertalk-request@contesting.com writes:

Send  TowerTalk mailing list submissions to
towertalk@contesting.com

To subscribe or unsubscribe via the World Wide  Web, visit
http://lists.contesting.com/mailman/listinfo/towertalk
or, via email, send  a message with subject or body 'help' to
towertalk-request@contesting.com

You can reach the person managing the  list at
towertalk-owner@contesting.com

When replying,  please edit your Subject line so it is more specific
than "Re: Contents of  TowerTalk digest..."


Today's Topics:

1. Re:  2000 Foot Tower, Antenna Replacement (Michael Germino)
2. Re:  Climbing and working on Rohn 25g/45g towers - (Roger (K8RI))
3. Tower Disaster (Mark Robinson)
4. Inverted L Tuning  Question (RLVZ@aol.com)
5. Re: Inverted L Tuning Question  (Richards)
6. Re: Inverted L Tuning Question (Tom  Osborne)
7. Re: Inverted L Tuning Question (Dennis  Vernacchia)
8. Re: Inverted L Tuning Question  (K2EK@aol.com)
9. Inverted L Tuning - Solved  (RLVZ@aol.com)
10. Re: Inverted L Tuning - Solved  (Richards)
11. Re: Inverted L Tuning Question (RICHARD  SOLOMON)


----------------------------------------------------------------------

Message:  1
Date: Wed, 3 Dec 2008 21:14:53 -0800 (PST)
From: Michael Germino  <ad6aa@sbcglobal.net>
Subject: Re: [TowerTalk] 2000 Foot Tower,  Antenna Replacement
To: Tower Talk  <towertalk@contesting.com>
Message-ID:  <842607.56021.qm@web82403.mail.mud.yahoo.com>
Content-Type:  text/plain; charset=us-ascii




I liked the watermelon they  threw off of the  tower.

Mike


------------------------------

Message:  2
Date: Thu, 04 Dec 2008 16:41:14 -0500
From: "Roger (K8RI)"  <K8RI-on-TowerTalk@tm.net>
Subject: Re: [TowerTalk] Climbing and  working on Rohn 25g/45g towers -
Cc:  towertalk@contesting.com
Message-ID:  <49384E7A.1000507@tm.net>
Content-Type: text/plain;  charset=ISO-8859-1; format=flowed



Bill Aycock wrote:
> I  have a real problem with this. I have asked for a description of the way 
a  
> force is applied to the tower, and how the tower section is mounted,  to 
show 
>   
Shear strength is perpendicular to the tower  (or brace) and even if we 
know how it was measured it doesn't give us a  lot of information as a 
load is seldom applied in a direct shear mode. (It  would be if tied to a 
horizontal brace.)  There is almost always some  bending moment.  I think 
it was mentioned earlier that shear is in  the weakest direction. It also 
has very little to do with normal antenna  loading unless the antenna is 
located right at a guy point, or as in the  case of a TIC Ring.  Maximum 
antenna wind load is a small fraction of  the shear strength.

What scares me is watching some one climb one of  the Aluminum towers 
while bending the braces from their weight.

I  wouldn't call it silly, but I agree, "shear strength" in most cases 
tells  us little in the practical sense.

73

Roger (K8RI)
> how  this "strength" is defined. So far I have no luck.
> Tossing phrases  like "Shear Strength" around without knowing what they 
mean 
> is  silly.
> Bill--W4BSG
>
> ----- Original Message -----  
> From: "Bill Coleman" <aa4lr@arrl.net>
> To: "Richard  Elizondo" <relizondo@ionoscom.com>
> Cc:  <towertalk@contesting.com>
> Sent: Thursday, December 04, 2008  7:07 AM
> Subject: Re: [TowerTalk] Climbing and working on Rohn 25g/45g  towers -
>
>
>   
>> On Nov 23, 2008, at  11:43 PM, Richard Elizondo wrote:
>>
>>      
>>> Here is the shocking sad  truth:
>>>
>>> Rohn 25g section shearing strength -  2500lbs (this is the strength
>>> of the
>>> entire  section, all three legs and lattice, not just that one leg
>>> you  may be
>>> attaching to.
>>>
>>> So a Rohn  25g section could fail if a climber falls and the lanyard
>>>  shock
>>> pack does not activate, or the climber is using a  lanyard without a
>>> shock
>>>  pack.
>>>
>>> Sadly enough the Rohn 45g section is not  that much stronger.
>>>       
>>  However, in a fall arrest situation, it is unlikely that all of  the
>> arrest force occurs in the shear direction. 25G has  considerably more
>> vertical support strength. On a 200 foot 25G  tower, the static load on
>> the base likely exceeds 2500 lbs to  start.
>>
>>     
>>> Solutions  for the Climber:
>>>
>>> First and foremost - Never  attach to the Z lattice of these towers
>>> for  any
>>> reason.
>>>        
>> If a single weld fails, then the Z bracing will deform --  that
>> deformation will absorb some of the fall energy. The  remaining energy
>> will be directed at the remaining upper and lower  welds. It seems
>> unlikely that a 6 foot fall would create so much  energy as to undo
>> every weld on a section.
>>
>>  It does seem seriously unwise to attach to the top or bottom  "flat"
>> part of the bracing. There, a single weld failure would  likely allow
>> the fall arrest lanyard to detach from the tower  entirely.
>>
>> Bill Coleman, AA4LR, PP-ASEL     Mail: aa4lr@arrl.net
>> Quote: "Not within a thousand  years will man ever fly!"
>>           -- Wilbur Wright, 1901
>>
>>  _______________________________________________
>>
>>
>>
>>  _______________________________________________
>> TowerTalk mailing  list
>> TowerTalk@contesting.com
>>  http://lists.contesting.com/mailman/listinfo/towertalk 
>>   
>
>  _______________________________________________
>
>
>
>  _______________________________________________
> TowerTalk mailing  list
> TowerTalk@contesting.com
>  http://lists.contesting.com/mailman/listinfo/towertalk
>
>    


------------------------------

Message: 3
Date: Thu, 4  Dec 2008 16:53:06 -0500
From: "Mark Robinson"  <markrob@mindspring.com>
Subject: [TowerTalk] Tower Disaster
To:  <towertalk@contesting.com>
Message-ID:  <06a301c9565a$b1717d20$6600a8c0@hplaptop>
Content-Type: text/plain;  format=flowed; charset="iso-8859-1";
reply-type=original

This a tragic story and it shows how quickly things  can go wrong.

http://www.sbe36.org/1999/0212.html


Mark  N1UK



------------------------------

Message: 4
Date:  Thu, 4 Dec 2008 18:06:16 EST
From: RLVZ@aol.com
Subject: [TowerTalk]  Inverted L Tuning Question
To: topband@contesting.com,  towertalk@contesting.com
Message-ID:  <ccc.4559e55e.3669bc68@aol.com>
Content-Type: text/plain;  charset="US-ASCII"

Hi Guys,

I'm trying to set up a 160-m.  Inverted L for ARRL-160 this weekend but am 
having an interesting tuning  problem.  All thoughts appreciated!

The Inverted L is made up of  #12 stranded copper wire 136' in total length: 
82' vertical and 54'  horizontal.  The vertical wire is spaced 6' from a 88'  
self-supporting tower with a Cushcraft XM-240 mounted on top.   (XM-240 
elements 
are not grounded)   Initial radial system  is  2- 135' radials laying on the 
ground- not much but two similar  radials worked pretty well on my 60' tower 
last 
year as the towers are  150' from a salt water river.    

Placing the Antenna  Analyzer (AIM 4170) at the base of the Inverted L gets 
the following  measurements:

1) With the coax braid connected to the tower base which  has two 8' ground 
rods: lowest SWR is 3.9 at 1.776 Mhz and Z =  79.

2) With coax braid only connected to the two radials (and not the  tower 
base): lowest SWR is 1.62 at 1.614 Mhz and Z = 81.

It was my  understanding that the coax braid should be connected to both the 
radials  and the base of the towers gnd system, but as you can see the the 
minimum  SWR and resonant freq. go crazy when I do. 

Any recommendations what I  can do to get it working before tmw night?

73,
Dick-  K9OM


**************
Make your life easier with all your friends,  email, 
and favorite sites in one place.  Try it now.  
(http://www.aol.com/?optin=new-dp&amp;
icid=aolcom40vanity&amp;ncid=emlcntaolcom00000010)


------------------------------

Message:  5
Date: Thu, 04 Dec 2008 18:57:27 -0500
From: Richards  <jruing@ameritech.net>
Subject: Re: [TowerTalk] Inverted L Tuning  Question
To: RLVZ@aol.com
Cc: towertalk@contesting.com,  topband@contesting.com
Message-ID:  <49386E67.9070301@ameritech.net>
Content-Type: text/plain;  charset=ISO-8859-1; format=flowed

I would not connect it to the tower,  itself.  If the tower is connected to
the ground rods, then I would  just use radial wires laying on the ground.
I would lay more ground wires  if using just those.   In other words, I
would not include the  tower, per se, in my counterpoise system.

Your situation brings some  humor to mind:

Doctor asks =  Does it hurt?
Patient says  =  Only when I do this  (gesturing.)
Doctor says =  Well...  don't do this.

If connecting to tower is worse than using radials  alone..... then
don't do this. ....   ;-)

But seriously  folks...
I am sending some good research materials on L antennas to you  under
separate cover.   Hope they are useful

Just MY  take...    Good luck.    ////  Richards -  K8JHR    ////

======================================================



RLVZ@aol.com  wrote:
> 
> 1) With the coax braid connected to the tower base  which has two 8' ground 
> rods: lowest SWR is 3.9 at 1.776 Mhz and Z =  79.
> 
> 2) With coax braid only connected to the two radials (and  not the tower 
> base): lowest SWR is 1.62 at 1.614 Mhz and Z =  81.
>  

===========================================================


------------------------------

Message:  6
Date: Thu, 04 Dec 2008 18:09:12 -0800
From: "Tom Osborne"  <w7why@verizon.net>
Subject: Re: [TowerTalk] Inverted L Tuning  Question
To: "Towertalk" <towertalk@contesting.com>
Message-ID:  <0E4016C6EA6B46FF8B84B79D5E8E4840@Tom>
Content-Type: text/plain;  format=flowed; charset=iso-8859-1;
reply-type=original

Hi Dick

You can get some screwy readings if  there is a BC station nearby.  I can't 
even use my analyzer here on  my 160 inverted L because of RF from the local. 
I have to use the SWR  bridge in the shack.  73
Tom W7WHy



> Hi  Guys,
>
> I'm trying to set up a 160-m. Inverted L for ARRL-160  this weekend but am
> having an interesting tuning problem.  All  thoughts appreciated!
>
> The Inverted L is made up of #12  stranded copper wire 136' in total 
> length:
> 82' vertical and  54' horizontal.  The vertical wire is spaced 6' from a 
>  88'
> self-supporting tower with a Cushcraft XM-240 mounted on  top.  (XM-240 
> elements
> are not grounded)    Initial radial system is  2- 135' radials laying on 
> the
>  ground- not much but two similar radials worked pretty well on my 60' 
>  tower last
> year as the towers are 150' from a salt water  river.
>
> Placing the Antenna Analyzer (AIM 4170) at the base of  the Inverted L gets
> the following measurements:
>
> 1)  With the coax braid connected to the tower base which has two 8'  ground
> rods: lowest SWR is 3.9 at 1.776 Mhz and Z =  79.
>
> 2) With coax braid only connected to the two radials (and  not the tower
> base): lowest SWR is 1.62 at 1.614 Mhz and Z =  81.
>
> It was my understanding that the coax braid should be  connected to both 
> the
> radials and the base of the towers gnd  system, but as you can see the the
> minimum SWR and resonant freq. go  crazy when I do.
>
> Any recommendations what I can do to get it  working before tmw night?
>
> 73,
> Dick-  K9OM



------------------------------

Message: 7
Date:  Thu, 4 Dec 2008 18:22:55 -0800
From: "Dennis Vernacchia"  <n6ki73@gmail.com>
Subject: Re: [TowerTalk] Inverted L Tuning  Question
To: "Tom Osborne" <w7why@verizon.net>
Cc: Towertalk  <towertalk@contesting.com>
Message-ID:
<265781b30812041822k64364bb0g4171954c4d0ee774@mail.gmail.com>
Content-Type:  text/plain; charset=ISO-8859-1

The issue with teh AM BC Strong Signal  interference is addressed in
the Nov/DEC NCJ
( National Contest Journal  ) magazine article
..and article uses exact same antenna analyzer as Dick  is using  !
73, Dennsi N6KI

On Thu, Dec 4, 2008 at 6:09 PM, Tom  Osborne <w7why@verizon.net> wrote:

> Hi Dick
>
>  You can get some screwy readings if there is a BC station nearby.  I  can't
> even use my analyzer here on my 160 inverted L because of RF  from the
> local.
> I have to use the SWR bridge in the  shack.  73
> Tom W7WHy
>
>
>
> > Hi  Guys,
> >
> > I'm trying to set up a 160-m. Inverted L for  ARRL-160 this weekend but am
> > having an interesting tuning  problem.  All thoughts appreciated!
> >
> > The  Inverted L is made up of #12 stranded copper wire 136' in total
> >  length:
> > 82' vertical and 54' horizontal.  The vertical wire  is spaced 6' from a
> > 88'
> > self-supporting tower with a  Cushcraft XM-240 mounted on top.  (XM-240
> > elements
>  > are not grounded)   Initial radial system is  2- 135'  radials laying on
> > the
> > ground- not much but two  similar radials worked pretty well on my 60'
> > tower last
>  > year as the towers are 150' from a salt water river.
> >
>  > Placing the Antenna Analyzer (AIM 4170) at the base of the Inverted  L
> gets
> > the following measurements:
> >
>  > 1) With the coax braid connected to the tower base which has two  8'
> ground
> > rods: lowest SWR is 3.9 at 1.776 Mhz and Z =  79.
> >
> > 2) With coax braid only connected to the two  radials (and not the tower
> > base): lowest SWR is 1.62 at 1.614 Mhz  and Z = 81.
> >
> > It was my understanding that the coax  braid should be connected to both
> > the
> > radials and  the base of the towers gnd system, but as you can see the the
> >  minimum SWR and resonant freq. go crazy when I do.
> >
> >  Any recommendations what I can do to get it working before tmw night?
>  >
> > 73,
> > Dick- K9OM
>
>  _______________________________________________
>
>
>
>  _______________________________________________
> TowerTalk mailing  list
> TowerTalk@contesting.com
>  http://lists.contesting.com/mailman/listinfo/towertalk
>


------------------------------

Message:  8
Date: Thu, 4 Dec 2008 21:36:44 EST
From: K2EK@aol.com
Subject: Re:  [TowerTalk] Inverted L Tuning Question
To:  towertalk@contesting.com
Message-ID:  <c40.4c6ee701.3669edbc@aol.com>
Content-Type: text/plain;  charset="US-ASCII"

Rick

My inv-L is 60' vertical plus 75' +/-  sloping down and away from the tower 
(70' topped with an X7).  There  is 6' separation between the tower and 
vertical 
wire. I also use the tower  as a folded monopole on 80.  Consequently it is 
tied to the radials  (100 x 65').

I found I needed to use a series cap between the coax and  vertical wire. I 
think I wound up with 2 or 300pf. You could try a 2  section BC variable to 
get 
an idea.  In my case, the horizontal wire  started out at almost 85'.  I had 
to 
go back and forth between  trimming that and tuning the cap.  Eventually I 
had 
a very nice match  at 1835.  If this works for you, you can then improvise a 
HV 
cap by  using 12" pieces of scrap RG8.  Each piece will contribute about 28 - 
 
30pf (make sure you maintain 1/2" or so separation between braids and  center 
conductors).

I used an MFJ269 at the base for tuning.   It was oblivious to a 10Kw BC 
station 5 or 6 miles north of me.

73  and GL
Bill
K2EK
**************Make your life easier with all your  friends, email, and 
favorite sites in one place.  Try it now.  
(http://www.aol.com/?optin=new-dp&icid=aolcom40vanity&ncid=emlcntaolcom0000001
0)


------------------------------

Message:  9
Date: Thu, 4 Dec 2008 22:29:49 EST
From: RLVZ@aol.com
Subject:  [TowerTalk] Inverted L Tuning - Solved
To: topband@contesting.com,  towertalk@contesting.com
Message-ID:  <c81.4066087a.3669fa2d@aol.com>
Content-Type: text/plain;  charset="US-ASCII"

Hi Guys,

Thank You for all the wonderful  ideas on getting my 160-m. Inverted L tuned. 
 
Your ideas got me  going!

My first mistake was connecting the radial ground to my tower  ground.  
Here's 
what fixed the Inverted L:

1) Disconnected the  tower ground from the radial ground and the SWR improved.
2) Put in a new  10' ground rod at the base of the Inverted L and tied it 
into 
the radial  ground and the SWR dropped further to 1.8 @ 1.77 Mhz @ Z=28.
3) Now that  the Z was down where it should be I added the 50/25 ohm UNUN and 
presto:  SWR is 1.06 @ 1.761 Mhz.

Tomorrow I plan to cut the top of the L a  little shorter for resonance at 
1.830.

Hope to work you in the  ARRL-160 Test this weekend!

73,
Dick-  K9OM


**************
Make your life easier with all your friends,  email, 
and favorite sites in one place.  Try it now.  
(http://www.aol.com/?optin=new-dp&amp;
icid=aolcom40vanity&amp;ncid=emlcntaolcom00000010)


------------------------------

Message:  10
Date: Thu, 04 Dec 2008 22:33:21 -0500
From: Richards  <jruing@ameritech.net>
Subject: Re: [TowerTalk] Inverted L Tuning -  Solved
To: RLVZ@aol.com
Cc: towertalk@contesting.com,  topband@contesting.com
Message-ID:  <4938A101.3070507@ameritech.net>
Content-Type: text/plain;  charset=ISO-8859-1; format=flowed

Great - Glad to help -- You might try  a few extra radials, also, as I
believe that will bring the SWR down  naturally.   It does for my vertical
monopole.

Happy  trails.       ======== Richards - K8JHR   =============




RLVZ@aol.com wrote:
> 3) Now  that the Z was down where it should be I added the 50/25 ohm 
UNUN  and
> presto: SWR is 1.06 @ 1.761 Mhz.
> 
> Tomorrow I plan  to cut the top of the L a little shorter for resonance at 
>  1.830.


=====================================================


------------------------------

Message:  11
Date: Fri, 5 Dec 2008 04:18:50 +0000
From: RICHARD SOLOMON  <w1ksz@q.com>
Subject: Re: [TowerTalk] Inverted L Tuning  Question
To: TowerTalk <towertalk@contesting.com>
Message-ID:  <BAY130-W14097877AA81547E771715E0FE0@phx.gbl>
Content-Type:  text/plain; charset="iso-8859-1"


Is that article available on line  ?

Thanks, Dick, W1KSZ> Date: Thu, 4 Dec 2008 18:22:55 -0800>  From: 
n6ki73@gmail.com> To: w7why@verizon.net> CC:  towertalk@contesting.com> 
Subject: Re: 
[TowerTalk] Inverted L Tuning  Question> > The issue with teh AM BC Strong 
Signal 
interference is  addressed in> the Nov/DEC NCJ> ( National Contest Journal ) 
magazine  article> ..and article uses exact same antenna analyzer as Dick is 
using  !> 73, Dennsi N6KI> > On Thu, Dec 4, 2008 at 6:09 PM, Tom Osborne  
<w7why@verizon.net> wrote:> > > Hi Dick> >> > You  can get some screwy readings 
if 
there is a BC station nearby. I can't> >  even use my analyzer here on my 160 
inverted L because of RF from the> >  local.> > I have to use the SWR bridge in 
the shack. 73> > Tom  W7WHy> >> >> >> > > Hi Guys,> > >> >  > I'm trying to 
set up a 160-m. Inverted L for ARRL-160 this weekend but   am&> > > having an 
interesting tuning problem. All thoughts  appreciated!> > >> > > The Inverted L 
is made up of #12  stranded copper wire 136' in total> > > length:> >  >
82' vertical and 54' horizontal. The vertical wire is spaced 6'  from a> > > 
88'> > > self-supporting tower with a Cushcraft  XM-240 mounted on top. 
(XM-240> > > elements> > > are not  grounded) Initial radial system is 2- 135' 
radials laying on> > >  the> > > ground- not much but two similar radials 
worked 
pretty well  on my 60'> > > tower last> > > year as the towers are 150'  from a 
salt water river.> > >> > > Placing the Antenna  Analyzer (AIM 4170) at the 
base of the Inverted L> > gets> > >  the following measurements:> > >> > > 1) 
With the coax braid  connected to the tower base which has two 8'> > ground> > 
> 
 rods: lowest SWR is 3.9 at 1.776 Mhz and Z = 79.> > >> > >  2) With coax 
braid only connected to the two radials (and not the tower>  > > base): lowest 
SWR is 1.62 at 1.614 Mhz and Z = 81.> > >>  > > It was my understanding that 
the 
coax braid should be connected to  both> > > the> > > radials and the base of 
the towers gnd  system, but as you can see the the> > > minimum SWR
and  resonant freq. go crazy when I do.> > >> > > Any  recommendations what I 
can do to get it working before tmw night?> >  >> > > 73,> > > Dick- K9OM> >> 
>  _______________________________________________> >> >> >>  > 
_______________________________________________> > TowerTalk  mailing list> > 
TowerTalk@contesting.com> >  
http://lists.contesting.com/mailman/listinfo/towertalk> >>  
_______________________________________________> > > >  
_______________________________________________> TowerTalk mailing list>  
TowerTalk@contesting.com>  
http://lists.contesting.com/mailman/listinfo/towertalk

------------------------------

_______________________________________________
TowerTalk  mailing  list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk


End  of TowerTalk Digest, Vol 72, Issue  10
*****************************************



**************Make your life easier with all your friends, email, and 
favorite sites in one place.  Try it now. 
(http://www.aol.com/?optin=new-dp&icid=aolcom40vanity&ncid=emlcntaolcom00000010)
_______________________________________________



_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk

<Prev in Thread] Current Thread [Next in Thread>
  • [TowerTalk] 16om L, Jwpjj <=