Return-Path: Received: from mtain-mg04.r1000.mx.aol.com (mtain-mg04.r1000.mx.aol.com [172.29.96.204]) by air-md05.mail.aol.com (v128.1) with ESMTP id MAILINMD054-8b874bbafdf9145; Tue, 06 Apr 2010 05:25:13 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-mg04.r1000.mx.aol.com (Internet Inbound) with ESMTP id 46A5C380000B2; Tue, 6 Apr 2010 05:25:11 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Nz517-0007NL-Sd for rs_out_1@blacksheep.org; Tue, 06 Apr 2010 10:24:17 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Nz517-0007NC-5o for rsgb_lf_group@blacksheep.org; Tue, 06 Apr 2010 10:24:17 +0100 Received: from relay2.uni-heidelberg.de ([129.206.210.211]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1Nz515-0001xC-Hn for rsgb_lf_group@blacksheep.org; Tue, 06 Apr 2010 10:24:17 +0100 Received: from freitag.iup.uni-heidelberg.de (freitag.iup.uni-heidelberg.de [129.206.29.204]) by relay2.uni-heidelberg.de (8.13.8/8.13.8) with ESMTP id o369NIAq011754 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Tue, 6 Apr 2010 11:23:19 +0200 Received: from [129.206.29.99] (pc99.iup.uni-heidelberg.de [129.206.29.99]) by freitag.iup.uni-heidelberg.de (8.12.11.20060308/8.11.2) with ESMTP id o369OFvH015144 for ; Tue, 6 Apr 2010 11:24:15 +0200 Message-ID: <4BBAFE41.4020401@iup.uni-heidelberg.de> Date: Tue, 06 Apr 2010 11:26:25 +0200 From: =?ISO-8859-1?Q?Stefan_Sch=E4fer?= User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.1.8) Gecko/20100227 Thunderbird/3.0.3 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: In-Reply-To: X-Spam-Score: 1.4 (+) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001,RATWARE_GECKO_BUILD=1.426 Subject: Re: LF: RE: RE: W1VLF 9 Khz Antenna update Putting inductance near the top. Content-Type: multipart/alternative; boundary="------------010409070401030604080504" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.6 required=5.0 tests=HTML_20_30,HTML_FONTCOLOR_BLUE, HTML_MESSAGE autolearn=no version=2.63 X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false x-aol-global-disposition: G x-aol-sid: 3039ac1d60cc4bbafdf72ab0 X-AOL-IP: 193.82.116.20 X-Mailer: Unknown (No Version) --------------010409070401030604080504 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: quoted-printable X-MIME-Autoconverted: from 8bit to quoted-printable by relay2.uni-heidelberg.de id o369NIAq011754 Paul, If you have not yet read much about LF/VLF antennas (for TX) i recommend= =20 the website of Rik/ON7YD: http://www.strobbe.eu/on7yd/136ant/ There, you get all basic necessary informations for becoming QRV on=20 LF/VLF! It is published in a understandable way, also with some examples= =20 for calculations. I have read it several times when i started becoming QRV in 2003 :-)=20 Maybe you already know many of the informations but it's just nice to read= ! There is not really a big difference between 137 and 9 kHz if we think=20 about becoming QRV, except this: Voltages are much more higher Radiation resistances are much lower Inductors needed are much higher (and take much more time to wind ;-) ) Earth losses and coil losses are much higher PA losses are lower (if switched) Propagation on VLF seems to be more efficient Easy to built PAs Lower influence of the skin effect (positive in wires, negative in the=20 earth) No limitations of TX power or ERP ;-) ...and so on :-) 73, Stefan/DK7FC Am 05.04.2010 22:35, schrieb Paul A. Cianciolo: > Stefan, > Thank you for the explanation I will read several more times . > To better understand. > Thank you again > PauLC > > -----Original Message----- > *From:* Stefan Sch=E4fer > [mailto:owner-rsgb_lf_group@blacksheep.org]*On Behalf Of *Stefan > Sch=E4fer > *Sent:* Monday, April 05, 2010 9:51 AM > *To:* rsgb_lf_group@blacksheep.org > *Subject:* AW: RE: W1VLF 9 Khz Antenna update Putting inductance > near the top. > > Paul, > There will be a benefit for you, so if it is done easily, do it! > When it can be done easily, why can't you bring up all the L as > high as possible? > Imagine the E-field lines that come out of the antenna wire. You > can imagine that by an _analogical example_: > A garden hose, in the form of the antenna wire construction, with > many holes in it. Imagine you have a compressor on the bottom and > connect the hose there. The water pressure is equivalent to the > voltage, the compressor has the function to increase the pressure; > the coil has the function to increase the voltage. The hose > diameter is assumed to be very big against the hole diameter so > the pressure is almost the same at each part of the hose (even at > the end). Your goal is to bring as much water (water [liters]is > here equivalent to electrical charge [As](absolute value)) as > possible through the vertical part of the hose without loosing to > much on the way to the top. This is because, in the electrical > case, you want to fed as much current as possible through the > radiation resistance to radiate the power I^2*Rrad. The water > (charge) that comes out of the hose in the vertical part before > reaching the maximum vertical height is not crossing the upper > part of the radiation resistance and thus the ERP is smaller. So, > it is the best to place the compressor/coil as high as possible > since if the pressure/voltage in the vertical section is smaller > (like before the compressor/coil) there is not so much water > pressed through the holes in the vertical section! > And if you increase the horizontal section of the construction, > there are more holes in sum above the compressor and thus more > water is pressed through them at a given pressure. So, the more > holes the more water, or charge (=3Dcurrent per cycle) in the > vertical part. > This analogical model can explain even more but surely there are > also things that cannot be compared (like a AC water flow ;-); no > closed circuit... ). But for a first imagination it is useful in > my point of view ;-) > If you place all the L on the tower it will be optimal. Then, you > could use a simple wire that connects to your earth system > _without_ the need for a distance to other metallic parts, since > there is no HV on this wire any more! That makes it easier even more= ! > You can inject the power by applying a isolated primary on the > coil and connect it to your PA in the shack by a loudspeaker > cable. Or you need a transformer and inject it on the bottom of > the wire between earth and lower part of the coil. That may be > even a litte easier... > A later step will be to reduce the earth resistance but you can do > that after starting to come up on the band since there will be no > changes to the coil, maybe just to the output ratio of the PA > transformer. Which PA will you use? > Best 73 and much fun! > Stefan/DK7FC > --------------------------------------------------------------------= ---- > *Von:* owner-rsgb_lf_group@blacksheep.org im Auftrag von Paul A. > Cianciolo > *Gesendet:* So 04.04.2010 22:28 > *An:* rsgb_lf_group@blacksheep.org > *Betreff:* LF: RE: W1VLF 9 Khz Antenna update Putting inductance > near the top. > > Stefan > On page 60 and 61 of the Low Frequency Experimenters Handbook > Peter Dodd RSGB there is an example putting a coil near the top > of the antenna > In this case the transmitter is on 137 Khz and a of a portion > (1/2) of the "L" needed to resonate was moved near the top. > According to measurements by Rik Strobbe ON7YD an increase of 4 > to 5 db was measured. > Do you think it would be worth the effort to put 1/4 of the total > "L" needed near the top > I could do that very easily. > PaulC > W1VLF > --------------010409070401030604080504 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Paul,

If you have not yet read much about LF/VLF antennas (for TX) i recommend the website of Rik/ON7YD: http://www.strobbe.eu/on7yd/136ant/
There, you get all basic necessary informations for becoming QRV on LF/VLF! It is published in a understandable way, also with some examples for calculations.
I have read it several times when i started becoming QRV in 2003 :-) Maybe you already know many of the informations but it's just nice to read!

There is not really a big difference between 137 and 9 kHz if we think about becoming QRV, except this:
Voltages are much more higher
Radiation resistances are much lower
Inductors needed are much higher (and take much more time to wind ;-) )
Earth losses and coil losses are much higher

PA losses are lower (if switched)
Propagation on VLF seems to be more efficient
Easy to built PAs
Lower influence of the skin effect (positive in wires, negative in the earth)
No limitations of TX power or ERP ;-)

...and so on :-)


73, Stefan/DK7FC


Am 05.04.2010 22:35, schrieb Paul A. Cianciolo:
LF: Activity 3 Mar 2010
Stefan,
 
Thank you for the explanation I will read several more times .
To better understand.
 
Thank you again
 
PauLC
 
-----Original Message-----
From: Stefan Schäfer [mailto:owner-rsgb_lf_group@blacksheep.org]On Behalf Of Stefan Schäfer
Sent: Monday, April 05, 2010 9:51 AM
To: rsgb_lf_group@blacksheep.org
Subject: AW: RE: W1VLF 9 Khz Antenna update Putting inductance near the top.

Paul,
 
There will be a benefit for you, so if it is done easily, do it! When it can be done easily, why can't you bring up all the L as high as possible?
 
Imagine the E-field lines that come out of the antenna wire. You can imagine that by an analogical example:
A garden hose, in the form of the antenna wire construction, with many holes in it. Imagine you have a compressor on the bottom and connect the hose there. The water pressure is equivalent to the voltage, the compressor has the function to increase the pressure; the coil has the function to increase the voltage. The hose diameter is assumed to be very big against the hole diameter so the pressure is almost the same at each part of the hose (even at the end). Your goal is to bring as much water (water [liters]is here equivalent to electrical charge [As](absolute value)) as possible through the vertical part of the hose without loosing to much on the way to the top. This is because, in the electrical case, you want to fed as much current as possible through the radiation resistance to radiate the power I^2*Rrad. The water (charge) that comes out of the hose in the vertical part before reaching the maximum vertical height is not crossing the upper part of the radiation resistance and thus the ERP is smaller. So, it is the best to place the compressor/coil as high as possible since if the pressure/voltage in the vertical section is smaller (like before the compressor/coil) there is not so much water pressed through the holes in the vertical section!
And if you increase the horizontal section of the construction, there are more holes in sum above the compressor and thus more water is pressed through them at a given pressure. So, the more holes the more water, or charge (=current per cycle) in the vertical part.
This analogical model can explain even more but surely there are also things that cannot be compared (like a AC water flow ;-); no closed circuit... ). But for a first imagination it is useful in my point of view ;-)
 
If you place all the L on the tower it will be optimal. Then, you could use a simple wire that connects to your earth system without the need for a distance to other metallic parts, since there is no HV on this wire any more! That makes it easier even more!
You can inject the power by applying a isolated primary on the coil and connect it to your PA in the shack by a loudspeaker cable. Or you need a transformer and inject it on the bottom of the wire between earth and lower part of the coil. That may be even a litte easier...
 
A later step will be to reduce the earth resistance but you can do that after starting to come up on the band since there will be no changes to the coil, maybe just to the output ratio of the PA transformer. Which PA will you use?
 
Best 73 and much fun!
 
Stefan/DK7FC
Von: owner-rsgb_lf_group@blacksheep.org im Auftrag von Paul A. Cianciolo
Gesendet: So 04.04.2010 22:28
An: rsgb_lf_group@blacksheep.org
Betreff: LF: RE: W1VLF 9 Khz Antenna update Putting inductance near the top.

Stefan
 
On page 60 and 61 of the Low Frequency Experimenters Handbook Peter Dodd RSGB  there is an example putting a coil near the top of the antenna
In this case the transmitter is on 137 Khz and a of a portion (1/2) of the "L" needed to resonate was moved near the top. According to measurements by Rik Strobbe ON7YD  an increase of 4 to 5 db  was measured.
 
Do you think it would be worth the effort to put 1/4 of the total "L" needed near the top
I could do that very easily.
 
PaulC
W1VLF
 
 
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