Today's Topics:
1. Re: TO7CC (Ray Benny)
2. Ice (Tom W8JI)
3. Re: Ice (Mike Waters)
4. Re: Ice (Charlie Cunningham)
5. Re: Power stayed on! (Gary Smith)
6. Re: NQ4I (Mike Waters)
7. Re: Power stayed on! (ZR)
8. Question - optimum number of radials (DALE LONG)
9. Re: Question - optimum number of radials (Mike Waters)
10. Re: Question - optimum number of radials (Joe Subich, W4TV)
11. Re: Ice (n0tt1@juno.com)
12. Re: Ice (Gary and Kathleen Pearse)
13. Re: Question - optimum number of radials (Tom W8JI)
14. Re: Question - optimum number of radials (Brad Rehm)
15. Re: Question - optimum number of radials (Tom W8JI)
16. Re: Question - optimum number of radials (Dan Maguire)
17. Palomar R-X Noise Bridge (mapa50@windstream.net)
18. Re: Question - optimum number of radials (Richard Fry)
19. Re: Question - optimum number of radials (Charlie Cunningham)
20. Re: Question - optimum number of radials (Bill Cromwell)
21. Question - optimum number of radials (James Rodenkirch)
22. Re: Question - optimum number of radials (Carl)
23. Re: Palomar R-X Noise Bridge (Carl)
24. Re: Question - optimum number of radials (Charlie Cunningham)
25. Re: Question - optimum number of radials (Charlie Cunningham)
----------------------------------------------------------------------
Message: 1
Date: Thu, 13 Feb 2014 12:35:12 -0700
From: Ray Benny <rayn6vr@cableone.net>
Cc: "topband@contesting.com" <topband@contesting.com>, f6ira@sfr.fr
Subject: Re: Topband: TO7CC
Message-ID:
<CAC716YZb4xTKXcygPJcz2afMom=Dt-B-2BPLzkpHO-pe7V_4Uw@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1
Heard TO7CC at our SS yesterday on 80m CW - 0100z, until about 0130z. You
worked K6XT, but I was there too.
Will be looking for you on 80m CW at or Sunset this evening, about 0100z
and later.
73, & tnx,
Ray,
N6VR
On Thu, Feb 13, 2014 at 7:35 AM, Doug Renwick <ve5ra@sasktel.net> wrote:
I haven't heard them or seen spots on 160 or 80 for the west coast around
1400 UTC give or take.
Doug
-----Original Message-----
Try to focuse our work on top band each time as possible. Every nights
ops
are there. At the end of FT5ZM QRG back quiet but dont Forget that
another
guys still on fr?quences for you. Finaly team stay on the Island untill
sunday morning. D?pending cndx Est coast stations Can be ear half and
more
after SR. In FR time around 2H30 AM. Last night have strong noise even
on
80 didn't log much qso in lows bands.
TO7CC team
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Message: 2
Date: Thu, 13 Feb 2014 15:32:53 -0500
From: "Tom W8JI" <w8ji@w8ji.com>
To: <topband@contesting.com>
Subject: Topband: Ice
Message-ID: <EE168A8969984EEAB34FD00755CF9ABD@MAIN>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
The ice that fell off my Yagi's typically measures about 1" thick off the
largest pieces, and 1/2" thick on the smaller thicknesses. I'm going to
assume the thick pieces are from the bottoms, so that's probably like 3/4
inch radial ice.
We lost power just before sunset last night.The power lines are a mess on
my
road, I'd guess they use maybe 400 ft spans, so they broke in multiple
places. I expect days before we have commercial power.
All of my Yagis sprung back except the 40 meter antenna. The ice dropped
off
one side of the top antenna, so it rotated the elements enough to look
pretty ugly. The bottom 40M Yagi lived just fine until big chunks of ice
kept banging it, and then one side of one element bent.
Many ropes snapped. The next time I need to remember to go out and release
tension **before** the ice hits. Once it started icing, none of the ropes
running through pulleys could be released.
I have not looked at Beverages and in woods and fields, but I have a lot
of
tree and building damage so I expect some chain saw and receiving antenna
work.
All in all not bad for such a large amount of ice.
73 Tom
------------------------------
Message: 3
Date: Thu, 13 Feb 2014 14:47:50 -0600
From: Mike Waters <mikewate@gmail.com>
To: topband <topband@contesting.com>
Subject: Re: Topband: Ice
Message-ID:
<CA+FxYXiHU-Ca4h2vmTPWna0eAEeJEe4nZiYigFHs0vHcN6pSxQ@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1
The last ice storm surely would have taken down my 160m inverted-L, had it
not been for the counterweight at the end. (It's made from #16 THHN, not
very strong.) The pulley did not completely ice up, apparently because it
moved every so often as ice made the antenna heavier.
At one point, the ice on the antenna raised the counterweight way up in
the
air. After the ice melted, it all returned to the way it was before the
storm.
I lost one wire on one of the Beverages (where there was a kink from other
damage), but it's a matter of time before a bigger ice storm completely
takes down both Beverages. I'm toying with the idea of counterweights at
the ends to help protect them. The pulleys are already there.
73, Mike
www.w0btu.com
On Thu, Feb 13, 2014 at 2:32 PM, Tom W8JI <w8ji@w8ji.com> wrote:
Many ropes snapped. The next time I need to remember to go out and
release
tension **before** the ice hits. Once it started icing, none of the ropes
running through pulleys could be released.
------------------------------
Message: 4
Date: Thu, 13 Feb 2014 15:56:23 -0500
From: "Charlie Cunningham" <charlie-cunningham@nc.rr.com>
To: "'Tom W8JI'" <w8ji@w8ji.com>
Cc: topband@contesting.com
Subject: Re: Topband: Ice
Message-ID:
<!&!AAAAAAAAAAAYAAAAAAAAAF0xXac1rOhFkn7GlcEWNIjCgAAAEAAAABcLdiBM4ctDvrhTb4MHLlgBAAAAAA==@nc.rr.com>
Content-Type: text/plain; charset="us-ascii"
Yikes!!
BTW - that lower 40m yagi with the bent element probably works just fine!
I
don't know if you've ever modeled yagis with bent or missing elements,
but
the results are pretty interesting! Yagis just "want to work"! :-)
GL!
-----Original Message-----
From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of Tom
W8JI
Sent: Thursday, February 13, 2014 3:33 PM
To: topband@contesting.com
Subject: Topband: Ice
The ice that fell off my Yagi's typically measures about 1" thick off the
largest pieces, and 1/2" thick on the smaller thicknesses. I'm going to
assume the thick pieces are from the bottoms, so that's probably like 3/4
inch radial ice.
We lost power just before sunset last night.The power lines are a mess on
my
road, I'd guess they use maybe 400 ft spans, so they broke in multiple
places. I expect days before we have commercial power.
All of my Yagis sprung back except the 40 meter antenna. The ice dropped
off
one side of the top antenna, so it rotated the elements enough to look
pretty ugly. The bottom 40M Yagi lived just fine until big chunks of ice
kept banging it, and then one side of one element bent.
Many ropes snapped. The next time I need to remember to go out and release
tension **before** the ice hits. Once it started icing, none of the ropes
running through pulleys could be released.
I have not looked at Beverages and in woods and fields, but I have a lot
of
tree and building damage so I expect some chain saw and receiving antenna
work.
All in all not bad for such a large amount of ice.
73 Tom
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------------------------------
Message: 5
Date: Thu, 13 Feb 2014 17:31:12 -0500
From: "Gary Smith" <Gary@ka1j.com>
To: Topband@contesting.com
Subject: Re: Topband: Power stayed on!
Message-ID: <52FD47B0.21094.1E33A4C5@Gary.ka1j.com>
Content-Type: text/plain; charset=US-ASCII
Genuinely sorry to hear of the unfortunate damage this storm has done
to some of us. It takes so much effort to put things together in a
way that we're happy with and mother nature can undo it in a
heartbeat. Sandy did my damage with salt water submerging all my
external antenna switching systems as well as the loss of my wire
antennas which snapped from falling branches. This time I escaped
damage, I hope those affected get their equipment back to shape as
fast as possible.
73,
Gary
KA1J
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Message: 6
Date: Thu, 13 Feb 2014 16:38:38 -0600
From: Mike Waters <mikewate@gmail.com>
To: "John Harden, D.M.D." <jhdmd@bellsouth.net>, topband
<topband@contesting.com>
Subject: Re: Topband: NQ4I
Message-ID:
<CA+FxYXgC=ApjFEDmbqztKQpELGgGtsGQg8dw2tjSa9Mcx2TkAw@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1
Need heaters inside the elements, at least towards the ends, that can be
turned on to melt the ice.
Where there's a will, there's a way to do that.
73, Mike
www.w0btu.com
On Thu, Feb 13, 2014 at 2:51 PM, John Harden, D.M.D.
<jhdmd@bellsouth.net>wrote:
Hi all...well the antennas are starting to give up...so far I have
lost the top 40m KLM 4 el at 155 ft that is used for the MULT
station...it is dangling from the top of the tower..next to go will be
the 3 el Telrex 40m RUN top antenna...also ready to fold up is the
monster 8 el homebrew 8 el 20m on 89 ft boom...not looking good either
is the top 8 el 15m RUN antenna at 155 ft...I might very well lose the
rest of the antennas tonight...it is raining and ice pellets and the
loads keep increasing on the antennas...we had planed to operate in
the ARRL CW this coming weekend...not sure if there will be any
antennas left...tomorrow morning will end the storm around 11
am..temps are forecast to rise to 34 degrees F and maybe some melting
will tke place.
de Rick NQ4I
------------------------------
Message: 7
Date: Thu, 13 Feb 2014 17:48:33 -0500
From: "ZR" <zr@jeremy.mv.com>
To: <Gary@ka1j.com>, <Topband@contesting.com>
Subject: Re: Topband: Power stayed on!
Message-ID: <225E5B1916F14A4FA76F76D75928864A@computer1>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
Looks like we dodged the bullet here also. Storms are unpredictable and go
anywhere from right up the Hudson River valley to out to sea
Watching the storm track it took a sharp right turn over LI, NY and then a
NE tack past Boston and out to sea.
About 8" of fluff which stopped about 4PM and likely some rain later
tonight
from the back side as the temps get into the 40's. We are still getting a
few 25-30 mph gusts but not like earlier when it was pretty steady for
several hours.
I took one pass with the plowtruck at 430 so we can get in/out as needed
and
will do the cleanup tomorrow.
Carl
KM1H
Subject: Re: Topband: Power stayed on!
Genuinely sorry to hear of the unfortunate damage this storm has done
to some of us. It takes so much effort to put things together in a
way that we're happy with and mother nature can undo it in a
heartbeat. Sandy did my damage with salt water submerging all my
external antenna switching systems as well as the loss of my wire
antennas which snapped from falling branches. This time I escaped
damage, I hope those affected get their equipment back to shape as
fast as possible.
73,
Gary
KA1J
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Message: 8
Date: Thu, 13 Feb 2014 15:12:42 -0800 (PST)
From: DALE LONG <dale.long@prodigy.net>
To: "topband@contesting.com" <topband@contesting.com>
Subject: Topband: Question - optimum number of radials
Message-ID:
<1392333162.70654.YahooMailNeo@web184303.mail.ne1.yahoo.com>
Content-Type: text/plain; charset=iso-8859-1
I understand that 120 radials is the golden standard. ?At what point is
there no significant improvement?
How much worse is 60 radials? ?How much worse is 24 radials (4 of 1/4
lambda and 20 or 1/10 lambda)?
This may have been discussed in the past, but if there is any engineering
reference or field testing that has been done, I would like to know the
results.
Thanks
Dale - N3BNA
------------------------------
Message: 9
Date: Thu, 13 Feb 2014 17:18:14 -0600
From: Mike Waters <mikewate@gmail.com>
To: topband <topband@contesting.com>
Subject: Re: Topband: Question - optimum number of radials
Message-ID:
<CA+FxYXjgwWkbCmwTmpdR_K3q9Baw1Azdq08E7SmyO2zTv+QcGw@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1
w0btu.com/Optimum_number_of_ground_radials_vs_radial_length.html
Check the links on that page to N6LF, Rudy Severns' pages. His work has
been called the gold standard of radial science.
73, Mike
www.w0btu.com
On Thu, Feb 13, 2014 at 5:12 PM, DALE LONG <dale.long@prodigy.net> wrote:
I understand that 120 radials is the golden standard. At what point is
there no significant improvement?
How much worse is 60 radials? How much worse is 24 radials (4 of 1/4
lambda and 20 or 1/10 lambda)?
------------------------------
Message: 10
Date: Thu, 13 Feb 2014 18:26:14 -0500
From: "Joe Subich, W4TV" <lists@subich.com>
To: topband@contesting.com
Subject: Re: Topband: Question - optimum number of radials
Message-ID: <52FD5496.7050700@subich.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
N6LF has done quite a bit of actual testing of various in ground and
elevated radial systems. See: http://www.antennasbyn6lf.com/
K3LC has done extensive modeling of both in ground and elevated
radial systems: http://www2.gcc.edu/dept/elee/Faculty/Christman.htm
However, if the majority of your on/in ground radials are only 0.1 wave
you won't need many before the point of diminishing returns.
73,
... Joe, W4TV
On 2/13/2014 6:12 PM, DALE LONG wrote:
I understand that 120 radials is the golden standard. At what point is
there no significant improvement?
How much worse is 60 radials? How much worse is 24 radials (4 of 1/4
lambda and 20 or 1/10 lambda)?
This may have been discussed in the past, but if there is any engineering
reference or field testing that has been done, I would like to know the
results.
Thanks
Dale - N3BNA
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------------------------------
Message: 11
Date: Thu, 13 Feb 2014 23:54:38 +0000
From: <n0tt1@juno.com>
To: mikewate@gmail.com,topband@contesting.com
Subject: Re: Topband: Ice
Message-ID: <AABKR4ZYRAXE9PR2@smtpout01.vgs.untd.com>
Content-Type: text/plain; charset=us-ascii
I lost one wire on one of the Beverages (where there was a kink from
other
damage), but it's a matter of time before a bigger ice storm
completely
takes down both Beverages. I'm toying with the idea of
counterweights at
the ends to help protect them. The pulleys are already there.
73, Mike
www.w0btu.com
FWIW, I rigged all my PVC Beverage poles so they are
simply zip-tied to metal T-posts. When an ice storm
is predicted, all that needs to be done is to clip the
ties and let the poles/wire fall to the ground. It takes
about 1/2 hour (if even that) to set them upright after the storm.
73,
Charlie, N0TT
------------------------------
Message: 12
Date: Thu, 13 Feb 2014 16:47:32 -0900
From: Gary and Kathleen Pearse <pearse@gci.net>
To: topband List <topband@contesting.com>
Subject: Re: Topband: Ice
Message-ID: <2E02DF8A-4B32-4F29-B746-330687DA16B6@gci.net>
Content-Type: text/plain; charset=windows-1252
I believe OH8X had one or more ?hammers? mounted to their 160 Yagi to help
remove the ice buildup. Sadly their extraordinary effort recently fell
victim to winds and reportedly torque:
http://dx-world.net/2013/oh8x-tower-collapse/
Not sure what the answer is. My Puny 3-el SteppIR with fiberglass elements
and retracted innards survived a November ice storm, gusts 60-70 reported
locally, and a direct hit to the director by a falling tree and the 160
Inv-L wire. One bracket is bent some, the boom is bent some, but it still
works. Repairs when it?s warmer.
Take care, there?s more on the way as far as Lower 48?s stormy WX:
http://www.weatherstreet.com/states/gfsx-sfc-temperature-and-wind-forecast.htm
http://www.weatherstreet.com/states/gfsx-slp-forecast.htm
73, Gary NL7Y
------------------------------
Message: 13
Date: Thu, 13 Feb 2014 20:49:47 -0500
From: "Tom W8JI" <w8ji@w8ji.com>
To: "DALE LONG" <dale.long@prodigy.net>, <topband@contesting.com>
Subject: Re: Topband: Question - optimum number of radials
Message-ID: <84F3D7BE677E47A2B53E9FCB1780E6F2@MAIN>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
I understand that 120 radials is the golden standard. At what point is
there
no significant improvement?>>>
120 radials never was a gold standard.
The FCC said if a AM BC station uses something like 110 radials, I forget
the exact number, they can avoid doing a radial system proof of
performance.
I think Hams assumed that somehow meant 110 radials or whatever the exact
number was were somehow "perfect".
There is no improvement here on 40M at about 20-30 radials. YMMV.
This will be different on different bands at the same location, and
different on the same bands at different locations, and even different
with
different antennas. So what happens in one cause is probably not true in
others.
Read carefully, and you will see even Rudy Severns says that, so his gold
standard isn't gold.
73 Tom
------------------------------
Message: 14
Date: Thu, 13 Feb 2014 20:11:26 -0600
From: Brad Rehm <bradrehm@gmail.com>
To: Tom W8JI <w8ji@w8ji.com>
Cc: DALE LONG <dale.long@prodigy.net>, "topband@contesting.com"
<topband@contesting.com>
Subject: Re: Topband: Question - optimum number of radials
Message-ID:
<CABBfdyTt1es+L42hZ8FtBAunqd7Aiu-Lz3xK0z_nJP6cJ9E3Aw@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1
Jerry Sevick, W2FMI, has an interesting comment about the "120" number in
his book, "The Short Vertical Antenna and Ground Radial." At the end of
the first chapter he notes:
"...it should be mentioned that the world standard for the number of
radials to be used with verticals in the AM broadcast band is 120. This
number was based on the classic paper published in 1937 by Brown, Lewis,
and Epstein. During the course of a business meeting with Dr. Brown, I
asked him how he and his colleagues arrived at the 120 radial
figure--because I was quite sure 100 would work as well. His answer was
interesting.
"He said that he and the others had been thinking in terms of 100 radials,
but the farmer who plowed in 100 radials had wire left over because copper
is soft and stretches easily. When he asked what to do with the extra
wire, the farmer was told to plow it in. The result was a world standard
of 120 radials."
Hmmmm!
Brad, KV5V
On Thu, Feb 13, 2014 at 7:49 PM, Tom W8JI <w8ji@w8ji.com> wrote:
I understand that 120 radials is the golden standard. At what point is
there no significant improvement?>>>
120 radials never was a gold standard.
The FCC said if a AM BC station uses something like 110 radials, I forget
the exact number, they can avoid doing a radial system proof of
performance. I think Hams assumed that somehow meant 110 radials or
whatever the exact number was were somehow "perfect".
There is no improvement here on 40M at about 20-30 radials. YMMV.
This will be different on different bands at the same location, and
different on the same bands at different locations, and even different
with
different antennas. So what happens in one cause is probably not true in
others.
Read carefully, and you will see even Rudy Severns says that, so his gold
standard isn't gold.
73 Tom
_________________
Topband Reflector Archives - http://www.contesting.com/_topband
------------------------------
Message: 15
Date: Thu, 13 Feb 2014 22:39:11 -0500
From: "Tom W8JI" <w8ji@w8ji.com>
To: "Brad Rehm" <bradrehm@gmail.com>
Cc: DALE LONG <dale.long@prodigy.net>, topband@contesting.com
Subject: Re: Topband: Question - optimum number of radials
Message-ID: <DF7DD3536C7E4377BD095F7CFCBEE760@MAIN>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
Jerry Sevick, W2FMI, has an interesting comment about the "120" number in
his book, "The Short Vertical Antenna and Ground Radial." At the end of
the first chapter he notes:
"...it should be mentioned that the world standard for the number of
radials to be used with verticals in the AM broadcast band is 120. This
number was based on the classic paper published in 1937 by Brown, Lewis,
and Epstein. During the course of a business meeting with Dr. Brown, I
asked him how he and his colleagues arrived at the 120 radial
figure--because I was quite sure 100 would work as well. His answer was
interesting.
"He said that he and the others had been thinking in terms of 100
radials,
but the farmer who plowed in 100 radials had wire left over because
copper
is soft and stretches easily. When he asked what to do with the extra
wire, the farmer was told to plow it in. The result was a world standard
of 120 radials."
That's an interesting story, but the story-teller must never have looked
at
the papers.
BL and E used 113 radials maxium, not 120.
Brown, Lewis, and Epstein's papers are all over the web, if you search for
them.
The FCC says:
"At the present development of the art, it is considered that where a
vertical radiator is employed with its base on the ground, the ground
system
should consist of buried radial wires at least one-fourth wave length
long.
There should be as many of these radials evenly spaced as practicable and
in
no event less than 90. (120 radials of 0.35 to 0.4 of a wave length in
length and spaced 3? is considered an excellent ground system and in case
of
high base voltage, a base screen of suitable dimensions should be
employed.)"
So you see, the FCC requires 90 radials unless you prove you can make
efficiency with fewer. They do not say 120 quarter wave radials, they
require 90 1/4 wave or longer, and say 120 radials .35 to .4 wl is
"considered excellent".
------------------------------
Message: 16
Date: Thu, 13 Feb 2014 20:18:13 -0800 (PST)
From: Dan Maguire <djm2150@yahoo.com>
To: topband@contesting.com
Subject: Re: Topband: Question - optimum number of radials
Message-ID:
<1392351493.14884.YahooMailBasic@web122606.mail.ne1.yahoo.com>
Content-Type: text/plain; charset=us-ascii
For anyone interested in modeling a vertical with a variable number of
radials you might refer back to this post:
http://lists.contesting.com/archives//html/Topband/2013-04/msg00017.html
Near the bottom you'll find a link to download a ".weq" format model for
use with AutoEZ. AutoEZ requires Microsoft Excel and EZNEC v5.
(Shooting myself in the foot here.) Even using the free demo version of
AutoEZ you can still take advantage of the "multi-config" aspect of the
model. Manually set the variables to any desired values (such as variable
"N" for number of radials) then use the "View Ant" button. That will
build a temporary .ez format model and send it to EZNEC. Then switch over
to the EZNEC main window and click the EZNEC "FF Plot" button or other
buttons as desired. In effect you are using AutoEZ to build the model and
EZNEC to process it.
If you don't have the Pro/4 (NEC-4) version of EZNEC you can simulate
buried radials by putting them ~0.001 wavelengths above ground. For info
on that subject see the EZNEC Help Index > Elevated Radial Systems.
Dan, AC6LA
http://ac6la.com
------------------------------
Message: 17
Date: Thu, 13 Feb 2014 23:18:07 -0600
From: <mapa50@windstream.net>
To: topband@contesting.com
Subject: Topband: Palomar R-X Noise Bridge
Message-ID: <20140214001807.3QQMJ.853.root@pamxwww05-z01>
Content-Type: text/plain; charset=utf-8
I have a question about using the noise bridge. I have used it cut stubs
to 1/4 wavelength using 52 ohm cable with no problems. I now need some
stubs using 75 ohm cable which I have on hand.
Will the same procedure work for 75 ohm that works for 52 ohm cable, or
will the different impedance need to be accounted for. I started to cut
cable and this question came to me. My first thought is that it will work
fine, but I am not sure. I did some searches on the web but found nothing
about it. Any help would be appreciated.
Thanks, Pat Armstrong
KF5YZ
------------------------------
Message: 18
Date: Fri, 14 Feb 2014 06:00:00 -0600
From: "Richard Fry" <rfry@adams.net>
To: <topband@contesting.com>
Subject: Re: Topband: Question - optimum number of radials
Message-ID: <6FA17FB496BE4653A5A92F3BDC833C43@ToshLaptop>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
The r-f loss at the operating frequency in a set of buried radials varies
with the conductivity and permittivity of the earth in which they are
buried.
The NEC4.2 study below shows that for poor earth conditions (within about
1/2WL from the base of the monopole), the number and length of buried
radials needed to maintain an r-f loss of a few ohms in the ground return
rises from that needed for more conductive earth.
In the case of AM broadcast stations, the use of 120 buried radials each
1/4-wavelength (in free space) produces a ground system loss of 2 ohms or
less. This is true no matter what are the characteristics of the the
earth
in which those 120 radials are buried.
For a 1/4-wave, unloaded monopole with 35 ohms of radiation resistance and
2
ohms of ground system loss, antenna system radiation efficiency is 35/37 =
95% of the applied power (approx).
The FCC requires that a minimum inverse distance groundwave field of 241
mV/m is produced by an applied power of 1 kW at at a distance of 1 km by
even the lowest class of AM station (Class C). A perfect 1/4-wave
monopole
driven against a perfect ground plane produces about 313 mV/m for those
conditions.
A typical installation using an unloaded 1/4-wave monopole driven against
120 x 1/4-wave buried radials produces about 306 mV/m for those
conditions -- which field is consistent with a monopole system with a
radiation efficiency of 95%.
The 241 mV/m minimum field required for Class C AM stations could be
produced by a 1/4-wave monopole+ground system with about 59% efficiency.
Class A AM stations such as WLW, WJR, WGN etc are required to generate an
inverse distance groundwave field of 362 mV/m at 1 km for 1 kW of applied
power. This cannot be done with a 1/4-wave monopole. Most of the Class A
stations use monopole heights ranging from 180 to 195 degrees.
WJR, Detroit uses a 195-deg monopole system that produces about 403 mV/m
at
1 km for 1 kW of applied power. At their licensed transmitter power of 50
kW, that field becomes 403 x SQRT(50) = 2.85 V/m, approx.
http://i62.photobucket.com/albums/h85/rfry-100/10m_Vert32Buried_Radials.jpg
RF
------------------------------
Message: 19
Date: Fri, 14 Feb 2014 09:15:59 -0500
From: "Charlie Cunningham" <charlie-cunningham@nc.rr.com>
To: "'Richard Fry'" <rfry@adams.net>, <topband@contesting.com>
Subject: Re: Topband: Question - optimum number of radials
Message-ID:
<!&!AAAAAAAAAAAYAAAAAAAAAF0xXac1rOhFkn7GlcEWNIjCgAAAEAAAAAMEJ5A3lqBAovrQH1mUupABAAAAAA==@nc.rr.com>
Content-Type: text/plain; charset="us-ascii"
That's a lot of good information, Richard! Thanks for sharing!
73,
Charlie, K4OTV
-----Original Message-----
From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of Richard
Fry
Sent: Friday, February 14, 2014 7:00 AM
To: topband@contesting.com
Subject: Re: Topband: Question - optimum number of radials
The r-f loss at the operating frequency in a set of buried radials varies
with the conductivity and permittivity of the earth in which they are
buried.
The NEC4.2 study below shows that for poor earth conditions (within about
1/2WL from the base of the monopole), the number and length of buried
radials needed to maintain an r-f loss of a few ohms in the ground return
rises from that needed for more conductive earth.
In the case of AM broadcast stations, the use of 120 buried radials each
1/4-wavelength (in free space) produces a ground system loss of 2 ohms or
less. This is true no matter what are the characteristics of the the
earth
in which those 120 radials are buried.
For a 1/4-wave, unloaded monopole with 35 ohms of radiation resistance and
2
ohms of ground system loss, antenna system radiation efficiency is 35/37 =
95% of the applied power (approx).
The FCC requires that a minimum inverse distance groundwave field of 241
mV/m is produced by an applied power of 1 kW at at a distance of 1 km by
even the lowest class of AM station (Class C). A perfect 1/4-wave
monopole
driven against a perfect ground plane produces about 313 mV/m for those
conditions.
A typical installation using an unloaded 1/4-wave monopole driven against
120 x 1/4-wave buried radials produces about 306 mV/m for those
conditions -- which field is consistent with a monopole system with a
radiation efficiency of 95%.
The 241 mV/m minimum field required for Class C AM stations could be
produced by a 1/4-wave monopole+ground system with about 59% efficiency.
Class A AM stations such as WLW, WJR, WGN etc are required to generate an
inverse distance groundwave field of 362 mV/m at 1 km for 1 kW of applied
power. This cannot be done with a 1/4-wave monopole. Most of the Class A
stations use monopole heights ranging from 180 to 195 degrees.
WJR, Detroit uses a 195-deg monopole system that produces about 403 mV/m
at
1 km for 1 kW of applied power. At their licensed transmitter power of 50
kW, that field becomes 403 x SQRT(50) = 2.85 V/m, approx.
http://i62.photobucket.com/albums/h85/rfry-100/10m_Vert32Buried_Radials.jpg
RF
_________________
Topband Reflector Archives - http://www.contesting.com/_topband
------------------------------
Message: 20
Date: Fri, 14 Feb 2014 10:02:08 -0500
From: Bill Cromwell <wrcromwell@gmail.com>
To: topband@contesting.com
Subject: Re: Topband: Question - optimum number of radials
Message-ID: <52FE2FF0.9020005@gmail.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
On 02/14/2014 09:15 AM, Charlie Cunningham wrote:
That's a lot of good information, Richard! Thanks for sharing!
73,
Charlie, K4OTV
The whole topic of radials as it applies to me on my small lot is "put
in as many as you can". The same probably applies to others on small
lots. On top band I do not have room in *any* direction for a quarter
wavelength radial..not even one. In some directions a quarter wavelength
radial wire might be bent to fit but that begins the many compromises.
Obviously that setup would have the antenna in one corner of the lot so
there would be no radials at all in one or two directions. So.. no
quarter wave radials at all. I have been buying small spools of wire and
will be adding them to whatever puny little radial field I DO have.
As soon as the ice and snow is gone (maybe in June?) I will be elevating
my wire antenna the rest of the way to the treetops and adding in the
radial wires. In the process of elevating the antenna I will learn to be
ace with a rod n reel <grin>. The whole point of that exercise is to
*miss* the tree and go over the top. So far I've only ever tried to
*hit* a spot out on the water. It's not hard to hit the water <wink>. I
didn't do too badly finding a particular spot on the water with the
bait. But the tree top is not "over" there. It's "up" there.
73,
Bill KU8H
------------------------------
Message: 21
Date: Fri, 14 Feb 2014 08:41:35 -0700
From: James Rodenkirch <rodenkirch_llc@msn.com>
To: Top Band Contesting <topband@contesting.com>
Subject: Topband: Question - optimum number of radials
Message-ID: <SNT148-W487C0FC2C2747602FAEBC2F09C0@phx.gbl>
Content-Type: text/plain; charset="iso-8859-1"
Besides "optimim number(s)," I wonder if there is supporting analysis for
the connection of the radial ends??
I have around 80 elevated radials that range from 50 foot lengths, running
east and west, and 25 foot lengths running north and south (all of that a
function of being geographically challenged). I have not tied the bitter
ends together....never really thought about it when I put the radial field
together but seem to recall reading something about tieing the ends
together and having a well bounded complete "grid" underthe antenna.
Thoughts? I tend to think it wouldn't hurt... 72, Jim Rodenkirch K9JWV
------------------------------
Message: 22
Date: Fri, 14 Feb 2014 10:45:58 -0500
From: "Carl" <km1h@jeremy.mv.com>
To: "Tom W8JI" <w8ji@w8ji.com>
Cc: topband@contesting.com
Subject: Re: Topband: Question - optimum number of radials
Message-ID: <366EBBA2AB1E427787B844AE3CB1479C@computer1>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=response
While Tom touched on the subject yesterday the subject of an individuals
ground conductivity has to be stressed, continuously it seems. The FCC
maps
arent perfect and hams usually dont have the options of perfect siting for
their verticals as do many of the BC stations.
Home developers often remove all of the good topsoil and sell it. They
back
fill with rocky sand and whatever else is cheap or worthless and finish
with
a skimcoat of real topsoil just thick enough to grow grass.
My own attempt with 60-65 quarter wave radials 30 years ago at another
home
were dismal since the "ground" was pure sand left behind by the glaciers
with a fresh water table about 4' down. Great for mixing concrete and
drainage only.
After I installed a 2X4" fence mesh around the base and out 50' could I
reliably work DX.
Going to elevated radials here on a granite hill in the same town saved a
lot of work and works very well.
Carl
KM1H
------------------------------
Message: 23
Date: Fri, 14 Feb 2014 10:54:14 -0500
From: "Carl" <km1h@jeremy.mv.com>
To: <mapa50@windstream.net>, <topband@contesting.com>
Subject: Re: Topband: Palomar R-X Noise Bridge
Message-ID: <183FA4B484E9475C839DD295602A937D@computer1>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
I used a noise bridge to cut all the RG-11 stacked yagi and phased
verticals
phasing lines as well as harmonic stubs here when running a 2 station
single
op contest, before SO2R.
Using the station receiver also works well as the backround noise null is
easily heard. I did that several times when a 9V battery was dead and
compared results later, they were right on.
Carl
KM1H
----- Original Message -----
From: <mapa50@windstream.net>
To: <topband@contesting.com>
Sent: Friday, February 14, 2014 12:18 AM
Subject: Topband: Palomar R-X Noise Bridge
I have a question about using the noise bridge. I have used it cut stubs
to
1/4 wavelength using 52 ohm cable with no problems. I now need some stubs
using 75 ohm cable which I have on hand.
Will the same procedure work for 75 ohm that works for 52 ohm cable, or
will the different impedance need to be accounted for. I started to cut
cable and this question came to me. My first thought is that it will work
fine, but I am not sure. I did some searches on the web but found nothing
about it. Any help would be appreciated.
Thanks, Pat Armstrong
KF5YZ
_________________
Topband Reflector Archives - http://www.contesting.com/_topband
------------------------------
Message: 24
Date: Fri, 14 Feb 2014 10:54:41 -0500
From: "Charlie Cunningham" <charlie-cunningham@nc.rr.com>
To: "'Bill Cromwell'" <wrcromwell@gmail.com>, <topband@contesting.com>
Subject: Re: Topband: Question - optimum number of radials
Message-ID:
<!&!AAAAAAAAAAAYAAAAAAAAAF0xXac1rOhFkn7GlcEWNIjCgAAAEAAAAD4cUOc0kI9IhtNMmVa64cABAAAAAA==@nc.rr.com>
Content-Type: text/plain; charset="us-ascii"
Hi, Bill
Well, like you, I also live on a fairly small city lot with way too much
bedrock coming up to the surface and a long concrete driveway, so buried
radials just aren't feasible for me! So I hung my inverted L in a tall
tulip
poplar in one corner of the lot and I ran two elevated resonant radials
down
the fence lines - elevated about 5-6 feet. I worked good stuff all over
the
world including JA and Indian Ocean, and VK6. If I could hear 'em, I could
work 'em! BEST thing I EVER did for myself was to build a KAZ terminated
receiving loop for the low-bands 160-30m, so I could HEAR more! Worked
great!! And no, I didn't have 100 buried radials, but just a few elevated
resonant radials will produce very effective results for the transmit
antenna!
73
Charlie, K4OTV
-----Original Message-----
From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of Bill
Cromwell
Sent: Friday, February 14, 2014 10:02 AM
To: topband@contesting.com
Subject: Re: Topband: Question - optimum number of radials
On 02/14/2014 09:15 AM, Charlie Cunningham wrote:
That's a lot of good information, Richard! Thanks for sharing!
73,
Charlie, K4OTV
The whole topic of radials as it applies to me on my small lot is "put in
as
many as you can". The same probably applies to others on small lots. On
top
band I do not have room in *any* direction for a quarter wavelength
radial..not even one. In some directions a quarter wavelength radial wire
might be bent to fit but that begins the many compromises.
Obviously that setup would have the antenna in one corner of the lot so
there would be no radials at all in one or two directions. So.. no quarter
wave radials at all. I have been buying small spools of wire and will be
adding them to whatever puny little radial field I DO have.
As soon as the ice and snow is gone (maybe in June?) I will be elevating
my
wire antenna the rest of the way to the treetops and adding in the radial
wires. In the process of elevating the antenna I will learn to be ace with
a
rod n reel <grin>. The whole point of that exercise is to
*miss* the tree and go over the top. So far I've only ever tried to
*hit* a spot out on the water. It's not hard to hit the water <wink>. I
didn't do too badly finding a particular spot on the water with the bait.
But the tree top is not "over" there. It's "up" there.
73,
Bill KU8H
_________________
Topband Reflector Archives - http://www.contesting.com/_topband
------------------------------
Message: 25
Date: Fri, 14 Feb 2014 11:00:36 -0500
From: "Charlie Cunningham" <charlie-cunningham@nc.rr.com>
To: "'Carl'" <km1h@jeremy.mv.com>, "'Tom W8JI'" <w8ji@w8ji.com>
Cc: topband@contesting.com
Subject: Re: Topband: Question - optimum number of radials
Message-ID:
<!&!AAAAAAAAAAAYAAAAAAAAAF0xXac1rOhFkn7GlcEWNIjCgAAAEAAAAGfz2YpWO5lGhy14Kf5JOeEBAAAAAA==@nc.rr.com>
Content-Type: text/plain; charset="us-ascii"
Yeah, just a few elevated resonant radials can work wonders as you have
discovered, Carl! And rock does get in the way of buried radials!! The
models teach that elevated resonant radials should work very well!
73,
Charlie, K4OTV
-----Original Message-----
From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of Carl
Sent: Friday, February 14, 2014 10:46 AM
To: Tom W8JI
Cc: topband@contesting.com
Subject: Re: Topband: Question - optimum number of radials
While Tom touched on the subject yesterday the subject of an individuals
ground conductivity has to be stressed, continuously it seems. The FCC
maps
arent perfect and hams usually dont have the options of perfect siting for
their verticals as do many of the BC stations.
Home developers often remove all of the good topsoil and sell it. They
back
fill with rocky sand and whatever else is cheap or worthless and finish
with
a skimcoat of real topsoil just thick enough to grow grass.
My own attempt with 60-65 quarter wave radials 30 years ago at another
home
were dismal since the "ground" was pure sand left behind by the glaciers
with a fresh water table about 4' down. Great for mixing concrete and
drainage only.
After I installed a 2X4" fence mesh around the base and out 50' could I
reliably work DX.
Going to elevated radials here on a granite hill in the same town saved a
lot of work and works very well.
Carl
KM1H
_________________
Topband Reflector Archives - http://www.contesting.com/_topband
------------------------------
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