Re: Topband: Inv L Config

[Donald Chester]

My base insulated tower is 127' of Rohn 25G. An 80m half-wave dipole is 
attached at the 119' level, the ends of which droop down to about 100' at each 
end, with runs of Phillystran from the ends of the dipole to wooden poles in 
opposite directions, each about 350' away from the tower. End insulators over 
300' long!  Extensive buried radial ground system consists of several thousand 
feet of #12 copper.  The dipole is fed with open wire tuned feeders, and used 
on 80m and 40m, but works quite well when tuned to 160m as a quarter-wave 
dipole.  When using the tower as a vertical, the end of the OWL near the base 
of the tower is opened with a knife switch and left floating. The OWL runs up 
to the dipole through the interior of the tower, fixed in position with 
plexiglass spacers every 10 feet, maintaining the line conductors symmetrically 
about the geometric centre of the triangle for the entire length of the 
feedline.

Strictly speaking, this antenna is closer to a vertical tee than to a simple 
quarter-wave vertical.  Due to the proximity of the feed line to the tower 
along the full length, the dipole is close-coupled to the tower even though 
there is no metallic connection between the dipole or feeders to the tower at 
any point.  The measured base impedance is about 180 ohms resistive and a 
little more than 300 ohms inductively reactive, as opposed to the expected 
36-plus ohms and negligible reactance of a simple quarter-wave vertical.

Interestingly, with the bottom end of the OWL connected to the tower (which is 
accomplished using a knife  switch when the antenna is not in use, for any 
lightning protection it might offer), the base impedance of the tower drops 
much lower, exactly 50 ohms at 1812 kHz as indicated at 1:1 on a SWR bridge.  I 
once tried grounding the bottom end of the OWL directly to the radial system, 
and the measured base impedance of the tower dropped even lower, between 10 and 
20 ohms IIRC.  I run the antenna with the OWL floating, since that's what my 
ATU is designed for, but have never tried comparing field strengths between the 
OWL floating and bonded to the tower at the base.  The  system is usable all 
the way from 1800  to 2000 kHz by adjusting the single resonating capacitor in 
the ATU.  The measured base impedance varies across the band but remains within 
the range of the tuner, which consists of a simple parallel tuned circuit, one 
end  grounded to the radial system and a tap on th
 e coil leading to the base of the  tower.  The number of turns on the coupling 
coil were carefully adjusted by trial-and-error for the best match to a 450-ohm 
untuned OWL running from the shack to the dog-house at the tower, with no 
additional variable capacitors or inductors between the OWL and the coupling 
coil.  The resonant frequency of the ATU at the base of the tower is adjusted 
using a reversible DC motor and worm drive, controlled from the shack.

The prototype of the ATU was built with whatever scrap  pieces of coil stock I 
could find around the shack.  Some of it  consisted of much-degraded pieces of 
air-core coil stock with corroded wire and deteriorated plastic insulation.  
When I got it working to my satisfaction, I replaced the junky coils in the 
prototype with top-grade silver plated edge-wound coil stock and proper coil 
clips, salvaged from discarded broadcast equipment. To my surprise (and 
disappointment?), the final version of the tuner with the good quality coil 
stock worked exactly the same as the prototype made of pieces of junk coil.  
With identical DC input to the transmitter final for each measurement, the 
measured base current at the tower was exactly the same with either tuner.

Don k4kyv




From: donov...@starpower.net 
Sent: 06 December 2016 05:28
To: REFLECTOR: Topband
Subject: Re: Topband: Inv L Config

A very important caution about the performance of T-verticals
vs. Inverted-L verticals.



If the performance of your 40 meter antennas is important to
you and your T-vertical is within 300 feet of your 40 meter
antenna, its important that the top of your T should be less
than 55 feet long or more than 80 feet long.


Why? If the T-top is 55-66 feet long it will act as a 40 meter
director. If its 66-80 feet long it will behave as a 40 meter
reflector. Don't ask me how I discovered this...


If the top of a T-vertical needs to be 55-80 feet long and within
300 feet of a 40 meter antenna that you don't want to degrade,
its better to use an inverted-L vertical, which has little or no
affect on nearby higher frequency antennas.


73
Frank
W3LPL




- Original Message -

From: "Guy Olinger K2AV" 
To: "Jerry Keller" 
Cc: "REFLECTOR: Topband" 
Sent: Tuesday, December 6, 2016 5:05:37 AM
Subject: Re: Topband: Inv L Config

The horizontal section also radiates, more or less than the vertical
depends on the 

Re: Topband: Electric Fence Noise at W9RE

[k2qmf]

Did he have it turned on 

On Fri, 9 Dec 2016 13:52:44 -0500 cqtestk4xs--- via Topband
 writes:
> 
> Funny thing about electric fences...
> 
> I lease out 9 acres of my property in KH6 to a farmer who has an 
> electric fence around that part of the property.  As far as I can 
> tell it is totally silent.  I parked my truck next to the fence, 
> tuned to 1710 kHz and other than background noise, it was totally 
> quiet...no pops etc.  No antennas up yet, but this certainly looks 
> promising.  Any thoughts?
> 
> Bill K4XS/KH7XS
> 
> 
> 
> -Original Message-
> From: Mike Wetzel 
> To: topband 
> Sent: Fri, Dec 9, 2016 5:52 pm
> Subject: Topband: Electric Fence Noise at W9RE
> 
> Here is a link to Don's (WD8DSB) web site detailing our experience 
> in
> tracking down this noise.  
> 
>  
> 
> http://sites.google.com/site/w9reelectricfencerfi/
> 
>  
> 
> Many thanks for Don for his top notch experience in tracking this 
> down,.
> 
>  
> 
> Powerline noise is one thing but now in the pass couple of years I 
> have
> major noise problems from a bad fluorescent T8 ballast and an over 
> stressed
> wall wart all located from 1000 feet to 4000 feet away.  Very lucky 
> to have
> cooperative neighbor's considering  my unsightly antennas.
> 
>  
> 
> Thanks,
> 
>  
> 
> Mike W9RE
> 
>  
> 
> _
> Topband Reflector Archives - http://www.contesting.com/_topband
> 
> _
> Topband Reflector Archives - http://www.contesting.com/_topband
> 


Warning: Don't Use Probiotics Before You See This
Gundry MD
http://thirdpartyoffers.juno.com/TGL3141/584b1afb1764d1afa1668st04vuc
_
Topband Reflector Archives - http://www.contesting.com/_topband

Topband: Fwd: Re: Electric Fence Noise at W9RE

[K1FZ-Bruce]

-
 
Noise usually comes when vegetation starts touching the lowest wires. ' 
Roundup' weed control can  be a help. 
 
73
Bruce-k1fz

On Fri, 9 Dec 2016 14:41:59 -0500, James Wolf  wrote:

  I have a horse farm behind me that has electric fences all over their
smaller pens and larger pastures. When it is installed correctly and the
sender is working correctly they are quiet. Unfortunately, his are not. 
In some places he has the hot wire mounted below the lowest fence board to
keep the dogs from moving in certain areas where some of the wire is
touching the ground. The whole place needs completely redone. Luckily,
setting the NB on the radio to its lowest setting keeps the pops away and
the intermod is tolerable except in contests. I can usually just walk the
fence and hear it arcing, or I can tell which section is arcing by putting
my one good ear next to the wire and listening to it ring. I used to put
ferrite beads and capacitors in the older controllers to roll off the sharp
transition of off and on; I don't have to do that any longer. The bottom
line is that if installed correctly and if using any recent controllers, you
won't be bothered. 

Jim - KR9U

___

Funny thing about electric fences... 

I lease out 9 acres of my property in KH6 to a farmer who has an electric
fence around that part of the property. As far as I can tell it is totally
silent. I parked my truck next to the fence, tuned to 1710 kHz and other
than background noise, it was totally quiet...no pops etc. No antennas up
yet, but this certainly looks promising. Any thoughts?

Bill K4XS/KH7XS

_
Topband Reflector Archives - http://www.contesting.com/_topband

 

_
Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: Electric Fence Noise at W9RE

[James Wolf]

I have a horse farm behind me that has electric fences all over their
smaller pens and larger pastures.  When it is installed correctly and the
sender is working correctly they are quiet.  Unfortunately, his are not.
In some places he has the hot wire mounted below the lowest fence board to
keep the dogs from moving in certain areas where some of the wire is
touching the ground.  The whole place needs completely redone.   Luckily,
setting the NB on the radio to its lowest setting keeps the pops away and
the intermod is tolerable except in contests.  I can usually just walk the
fence and hear it arcing, or I can tell which section is arcing by putting
my one good ear next to the wire and listening to it ring.  I used to put
ferrite beads and capacitors in the older controllers to roll off the sharp
transition of off and on;  I don't have to do that any longer. The bottom
line is that if installed correctly and if using any recent controllers, you
won't be bothered.

Jim - KR9U

___

Funny thing about electric fences...

I lease out 9 acres of my property in KH6 to a farmer who has an electric
fence around that part of the property.  As far as I can tell it is totally
silent.  I parked my truck next to the fence, tuned to 1710 kHz and other
than background noise, it was totally quiet...no pops etc.  No antennas up
yet, but this certainly looks promising.  Any thoughts?

Bill K4XS/KH7XS



_
Topband Reflector Archives - http://www.contesting.com/_topband

Re: Topband: Electric Fence Noise at W9RE

[cqtestk4xs--- via Topband]

Funny thing about electric fences...

I lease out 9 acres of my property in KH6 to a farmer who has an electric fence 
around that part of the property.  As far as I can tell it is totally silent.  
I parked my truck next to the fence, tuned to 1710 kHz and other than 
background noise, it was totally quiet...no pops etc.  No antennas up yet, but 
this certainly looks promising.  Any thoughts?

Bill K4XS/KH7XS



-Original Message-
From: Mike Wetzel 
To: topband 
Sent: Fri, Dec 9, 2016 5:52 pm
Subject: Topband: Electric Fence Noise at W9RE

Here is a link to Don's (WD8DSB) web site detailing our experience in
tracking down this noise.  

 

http://sites.google.com/site/w9reelectricfencerfi/

 

Many thanks for Don for his top notch experience in tracking this down,.

 

Powerline noise is one thing but now in the pass couple of years I have
major noise problems from a bad fluorescent T8 ballast and an over stressed
wall wart all located from 1000 feet to 4000 feet away.  Very lucky to have
cooperative neighbor's considering  my unsightly antennas.

 

Thanks,

 

Mike W9RE

 

_
Topband Reflector Archives - http://www.contesting.com/_topband

_
Topband Reflector Archives - http://www.contesting.com/_topband

Topband: Electric Fence Noise at W9RE

[Mike Wetzel]

Here is a link to Don's (WD8DSB) web site detailing our experience in
tracking down this noise.  

 

http://sites.google.com/site/w9reelectricfencerfi/

 

Many thanks for Don for his top notch experience in tracking this down,.

 

Powerline noise is one thing but now in the pass couple of years I have
major noise problems from a bad fluorescent T8 ballast and an over stressed
wall wart all located from 1000 feet to 4000 feet away.  Very lucky to have
cooperative neighbor's considering  my unsightly antennas.

 

Thanks,

 

Mike W9RE

 

_
Topband Reflector Archives - http://www.contesting.com/_topband