Return-Path: Received: from mtain-mi10.r1000.mx.aol.com (mtain-mi10.r1000.mail.aol.com [172.21.131.168]) by air-di01.mail.aol.com (v129.4) with ESMTP id MAILINDI014-eab94ced9a231a0; Wed, 24 Nov 2010 18:05:07 -0500 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-mi10.r1000.mx.aol.com (Internet Inbound) with ESMTP id 34D733800008D; Wed, 24 Nov 2010 18:05:03 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1PLONJ-0002P3-9n for rs_out_1@blacksheep.org; Wed, 24 Nov 2010 23:03:41 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1PLONI-0002Ou-O8 for rsgb_lf_group@blacksheep.org; Wed, 24 Nov 2010 23:03:40 +0000 Received: from col0-omc1-s10.col0.hotmail.com ([65.55.34.20]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1PLONH-000054-2J for rsgb_lf_group@blacksheep.org; Wed, 24 Nov 2010 23:03:40 +0000 Received: from COL122-W52 ([65.55.34.7]) by col0-omc1-s10.col0.hotmail.com with Microsoft SMTPSVC(6.0.3790.4675); Wed, 24 Nov 2010 15:03:30 -0800 Message-ID: X-Originating-IP: [81.200.63.88] From: Lubos OK2BVG To: _RSGB_LF Date: Thu, 25 Nov 2010 00:03:30 +0100 Importance: Normal In-Reply-To: <4CED6CC1.6070302@iup.uni-heidelberg.de> References: <4CED6CC1.6070302@iup.uni-heidelberg.de> MIME-Version: 1.0 X-OriginalArrivalTime: 24 Nov 2010 23:03:30.0278 (UTC) FILETIME=[CF7D7860:01CB8C2B] X-Spam-Score: 0.9 (/) X-Spam-Report: autolearn=disabled,HTML_10_20=0.945,HTML_MESSAGE=0.001 Content-Type: multipart/alternative; boundary="_daa5a4dd-0066-4767-8236-314165318ff2_" Subject: RE: LF: new VLF antenna at DK7FC X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.0 required=5.0 tests=FORGED_HOTMAIL_RCVD, 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: 3039400cded24ced9a1f51c5 X-AOL-IP: 195.171.43.25 X-Mailer: Unknown (No Version) --_daa5a4dd-0066-4767-8236-314165318ff2_ Content-Type: text/plain; charset="iso-8859-2" Content-Transfer-Encoding: quoted-printable Hello Stefan! This is perfect idea! Thanks for information about your new VLF antenna=20 model. I continue with my tests of antenna as well. My last model use cabel=20 CAT7 (4x twisted pair cable shielded) and it seems be promising. I am goin= g to send you some photos to your home address - sorry, I can=B4t do it he= re. But your idea is great! I must to try it! 73! Lubos, OK2BVG ****************************** > Date: Wed, 24 Nov 2010 20:51:29 +0100 > From: Stefan.Schaefer@iup.uni-heidelberg.de > To: rsgb_lf_group@blacksheep.org > Subject: LF: new VLF antenna at DK7FC >=20 > Dear VLF, >=20 > Full of euphorism i want to tell you about my new VLF RX antenna. > You know my active antenna for VLF which is in use at my grabber:=20 > http://www.iup.uni-heidelberg.de/schaefer_vlf/8,97kHz%20active%20E%20fie= ld%20antenna%20by%20DK7FC.jpg >=20 > I have had the idea to separate the E field active antenna into a front= =20 > end and the rest of the circuit can be left in the shack! > The front end consists out of the first JFET, the 1MOhm and 10 MOhm=20 > resistor, the electrode(wire) and the C=3D20 nF. The diodes can be left= =20 > away. The rest of the circuit is now placed inside the shack. >=20 > This has the following advantages: > -The gain and or filters can be adjusted and optimised in the shack! > -There is no need for a (separate) power supply on the top of the antenn= a > -No need for a (metallic) box on the top of the antenna > -the electronic parts can be shrinked together with the wire(s) by=20 > shrink tubes (waterproof) > -No need for a coupling-decoupling network at the antenna for the power= =20 > supply > - If the use of batteries is an advantage, they can easily be=20 > replaced/charged/measured in the shack! > - A single twisted pair cable (e.g. 1/4 of a CAT5 cable) can be used > -When a tiny fishing rod is used to keep the active antenna apart from= =20 > the house, the distance can be increased due to optimised lightweight > :-) >=20 > I just have used a single twisted pair cable out of a CAT5 cable (now=20 > unshielded) at almost 30m length between the front end and the amp stage= =20 > in the shack. This allows me to get more distance to the tram line which= =20 > causes strong QRM on VLF on my grabber antenna. Now, this new antenna is= =20 > on the other side of the house. >=20 > See the difference between the 2 wideband captures: Old system, bottom= =20 > capture of=20 > http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber.html = =20 > and the new system, bottom of=20 > http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber2.html >=20 > So, at least on VLF this is a great chance to reduce the local noise.=20 > Maybe some others can do the same since a very small twisted pair cable= =20 > is almost invisible and cheep (i've used a 10m cable and soldered the=20 > pairs in series). No matter what the maximum distance might be but i can= =20 > imagine 100m will be not the problem! I will check to do the same on LF.= =20 > Since the length is still << Lambda i do not expect much trouble. >=20 > 73, Stefan/DK7FC >=20 =3D --_daa5a4dd-0066-4767-8236-314165318ff2_ Content-Type: text/html; charset="iso-8859-2" Content-Transfer-Encoding: quoted-printable Hello Stefan!

This is perfect idea! Thanks for information about your new VLF antenn= a=20 model.
I continue with my tests of antenna as well. My last model use cabel= =20 CAT7 (4x twisted pair cable shielded) and it seems be promising. I am goin= g to send you some photos to your home address - sorry, I can=B4t do it he= re.
But your idea is great! I must to try it!

73!

Lubos, OK2BVG

******************************
> Date: Wed, 24 Nov 2010 20:51:29 +0100
> From: Stefan.Schaefer@= iup.uni-heidelberg.de
> To: rsgb_lf_group@blacksheep.org
> Sub= ject: LF: new VLF antenna at DK7FC
>
> Dear VLF,
>
= > Full of euphorism i want to tell you about my new VLF RX antenna.
= > You know my active antenna for VLF which is in use at my grabber: > http://www.iup.uni-heidelberg.de/schaefer_vlf/8,97kHz%20active%20E%2= 0field%20antenna%20by%20DK7FC.jpg
>
> I have had the idea to= separate the E field active antenna into a front
> end and the res= t of the circuit can be left in the shack!
> The front end consists= out of the first JFET, the 1MOhm and 10 MOhm
> resistor, the elect= rode(wire) and the C=3D20 nF. The diodes can be left
> away. The re= st of the circuit is now placed inside the shack.
>
> This ha= s the following advantages:
> -The gain and or filters can be adjust= ed and optimised in the shack!
> -There is no need for a (separate)= power supply on the top of the antenna
> -No need for a (metallic)= box on the top of the antenna
> -the electronic parts can be shrink= ed together with the wire(s) by
> shrink tubes (waterproof)
>= -No need for a coupling-decoupling network at the antenna for the power=
> supply
> - If the use of batteries is an advantage, they= can easily be
> replaced/charged/measured in the shack!
> -= A single twisted pair cable (e.g. 1/4 of a CAT5 cable) can be used
>= ; -When a tiny fishing rod is used to keep the active antenna apart from=
> the house, the distance can be increased due to optimised lightw= eight
> :-)
>
> I just have used a single twisted pair= cable out of a CAT5 cable (now
> unshielded) at almost 30m length= between the front end and the amp stage
> in the shack. This allow= s me to get more distance to the tram line which
> causes strong QR= M on VLF on my grabber antenna. Now, this new antenna is
> on the= other side of the house.
>
> See the difference between the= 2 wideband captures: Old system, bottom
> capture of
> http= ://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber.html
>= ; and the new system, bottom of
> http://www.iup.uni-heidelberg.de/= schaefer_vlf/DK7FC_VLF_Grabber2.html
>
> So, at least on VLF= this is a great chance to reduce the local noise.
> Maybe some oth= ers can do the same since a very small twisted pair cable
> is almo= st invisible and cheep (i've used a 10m cable and soldered the
> pa= irs in series). No matter what the maximum distance might be but i can > imagine 100m will be not the problem! I will check to do the same on= LF.
> Since the length is still << Lambda i do not expect mu= ch trouble.
>
> 73, Stefan/DK7FC
>
= =3D --_daa5a4dd-0066-4767-8236-314165318ff2_--