Return-Path: Received: from rly-dg11.mx.aol.com (rly-dg11.mail.aol.com [172.19.151.95]) by air-dg08.mail.aol.com (v126.13) with ESMTP id MAILINDG084-6074b2d7f5b3a1; Sat, 19 Dec 2009 20:35:35 -0500 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by rly-dg11.mx.aol.com (v125.7) with ESMTP id MAILRELAYINDG118-6074b2d7f5b3a1; Sat, 19 Dec 2009 20:35:25 -0500 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1NMAcD-0004Rg-B6 for rs_out_1@blacksheep.org; Sun, 20 Dec 2009 01:29:45 +0000 Received: from [83.244.159.144] (helo=relay3.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1NMAcC-0004RX-FK for rsgb_lf_group@blacksheep.org; Sun, 20 Dec 2009 01:29:44 +0000 Received: from blu0-omc1-s7.blu0.hotmail.com ([65.55.116.18]) by relay3.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1NMAgQ-000804-1o for rsgb_lf_group@blacksheep.org; Sun, 20 Dec 2009 01:34:07 +0000 Received: from BLU146-W20 ([65.55.116.9]) by blu0-omc1-s7.blu0.hotmail.com with Microsoft SMTPSVC(6.0.3790.3959); Sat, 19 Dec 2009 17:33:58 -0800 Message-ID: X-Originating-IP: [218.67.241.10] From: Laurence BY3A-KL1X China To: Date: Sat, 19 Dec 2009 16:33:58 -0900 Importance: Normal In-Reply-To: <4B2CDA00.6080504@att.net> References: <38A51B74B884D74083D7950AD0DD85E828ACB3@File-Server-HST.hst.e-technik.tu-darmstadt.de> <346854e9698cbf94f4483c66682bb63b.squirrel@webmail.xs4all.nl> ,<4B2CDA00.6080504@att.net> MIME-Version: 1.0 X-OriginalArrivalTime: 20 Dec 2009 01:33:58.0443 (UTC) FILETIME=[803F1FB0:01CA8114] X-Spam-Score: 0.9 (/) X-Spam-Report: autolearn=disabled,HTML_10_20=0.945,HTML_MESSAGE=0.001 Content-Type: multipart/alternative; boundary="_17ba67a4-c08f-42fb-91bb-10d70bad56d0_" Subject: LF: E thingies X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: * X-Spam-Status: No, hits=1.6 required=5.0 tests=CELL_PHONE_BOOST, 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-IP: 193.82.116.20 X-Mailer: Unknown (No Version) --_17ba67a4-c08f-42fb-91bb-10d70bad56d0_ Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable James/Dex et al - Good morning - I concur with the findings on the eprobe= on the roof of the car. My mobile efforts tend to be was mounted on a tri= magnet mag mount and a short stub mast of about 12 inches to which the pro= be is attached. The coax (about 12ft total length) routed directly into= the car across the roof, but bonded to the rear passenger door frame wher= e it enters. This bond must be short and low reactance to stop the in car= noises getting up the coax to/close to the antennae. Makes big odds as yo= u go HF. =20 Got to say even with this very small effective height it worked well enoug= h on 137/500, but very dependant on the type of car, the bonding and curre= nts flowing out/in/capacitance to real ground.... =20 =20 I have a feeling Ill be resurrecting the system in Oklahoma to pass the ev= enings away... =20 For the house PA0RDT - I shove a Hi Z at LF common mode choke on the coax= outer (30T on J material or maybe it maybe a bit more lossy stuff ) just= one meter back from the eprobe, same at the other end of the coax just be= fore its bonded down to the door frame/balcony/rebar reinforcing. At the= receive end its galvanically decoupled with a 4T:4T type 77 small toroid= - good and flat till 15Mhz=20 =20 Now, how long it the antennae? Bonding still reduces the noise so there= must be small leakage from the coax past the upper choke - probably capac= itive coupling...it doesnt take much.=20 =20 Again good noise free bonding (if your lucky and get the right spot) can= and has given up to 50dB of noise reduction without it. Sometime less of= course. The BY3A apartment balcony was bonded back to the building rebar= and gave around 40dB improvement signal/noise on 137, but only had a very= small, maybe a dB increase in signal level. =20 Ive come to a conclusion to mount the probe away from the source of noises= and "dumping" of the E field. In my case I get the probe as high and away= so tend to have a 11m pole at around 45 degrees away from the building ov= er the side - in some cases I prefer to do that (s/n wise) than mounting= it 11m in the middle of an apartment roof. Ill always try to locate it= on a corner and away from the building with as much clearance to the "re= al" ground for the greatest clear space angle. I cant help walking around= towns now and view the skyline and each building and visualise how the LF= E field signal is disrupted close in by these new high rises that now dom= inate some skylines. =20 Laurence KL 1 X Enroute home. =20 > Date: Sat, 19 Dec 2009 08:49:52 -0500 > From: dmcintyre@att.net > To: rsgb_lf_group@blacksheep.org > Subject: Re: LF: Noise cancelling by using optic transmission of RX sign= als >=20 > James Moritz wrote: >=20 > > I think the role of the ground with active whips is often neglected -= =20 > > the output of the whip preamp is the voltage differential between the= =20 > > whip element and the circuit ground, so the ground connection is just= as=20 > > much part of the antenna as the whip element itself is. Clearly, an=20 > > electrically quiet ground is needed for the active whip, whether this= is=20 > > provided by the coax feeder or a separate local ground connection. >=20 > Years ago I built a simple MPF-102 active whip into a gutted VHF coil en= closure=20 > of a NMO mobile antenna. I quickly noticed the antenna performed much be= tter=20 > when mounted on a vehicle roof than when mounted on a mast. Even when th= e whip=20 > was elevated up to 10 meters above the vehicle the roof mount received= much better. >=20 > As for the optical link, I attempted to link a remote VLF-3 by IR back= to the=20 > shack. I never got that to work very well but I feel sure someone that= knows=20 > what they are doing could perfect it. >=20 > Dex >=20 =20 _________________________________________________________________ Hotmail: Free, trusted and rich email service. http://clk.atdmt.com/GBL/go/171222984/direct/01/=3D --_17ba67a4-c08f-42fb-91bb-10d70bad56d0_ Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable James/Dex et al - Good morning  - I concur with the findings on= the eprobe on the roof of the car. My mobile efforts tend to be= was mounted on a trimagnet mag mount and a short stub mast of about= 12 inches to which the probe is attached. The coax  (about= 12ft total length)  routed directly into the car across the roo= f, but bonded to the rear passenger door frame where it enters. This= bond must be short and low reactance to stop the in car noises getting up= the coax to/close to the antennae. Makes big odds as you go HF.
 
Got to say even with this very small effective height it worked well= enough on 137/500, but very dependant on the type of car, the bonding and= currents flowing out/in/capacitance to real ground....    =
 
I have a feeling Ill be resurrecting the system in Oklahoma to pass the ev= enings away...
 
For the house  PA0RDT - I shove a Hi Z at LF common mode choke on the= coax outer  (30T on J material or maybe it maybe a bi= t more lossy stuff ) just one meter back from the eprobe, same= at the other end of the coax just before its bonded down to the door fram= e/balcony/rebar reinforcing. At the receive end its galvanically deco= upled with a 4T:4T type 77 small toroid - good and flat till 15M= hz
 
Now, how long it the antennae?  Bonding still reduces the n= oise so there must be small leakage from the coax past the upper chok= e - probably capacitive coupling...it doesnt take much. 
 
Again good noise free bonding (if your lucky and get the right spot) can= and has given up to 50dB of noise reduction without it. Sometime less of= course.  The BY3A apartment balcony was bonded back to the building= rebar and gave around 40dB improvement signal/noise on 137, but only had= a very small, maybe a dB increase in signal level.
 
Ive come to a conclusion to mount the probe away from the source of noises= and "dumping" of the E field. In my case I get the probe as high and away= so tend to have a 11m pole at around 45 degrees away from the building ov= er the side - in some cases I prefer to do that (s/n wise) than mounting= it 11m in the middle of an apartment  roof.   Ill always&n= bsp;try to locate it on a corner and away from the  building&nbs= p;with as much clearance to the "real" ground for the greatest clear space= angle. I cant help walking around towns now and view the skyline and each= building and visualise how the LF E field signal is disrupted close= in by these new high rises that now dominate some skylines.
 
Laurence KL 1 X
Enroute home.

 
> Date: Sat, 19 Dec 2009 08:49:52 -0500
> From: dmc= intyre@att.net
> To: rsgb_lf_group@blacksheep.org
> Subject:= Re: LF: Noise cancelling by using optic transmission of RX signals
>= ;
> James Moritz wrote:
>
> > I think the role of= the ground with active whips is often neglected -
> > the outpu= t of the whip preamp is the voltage differential between the
> >= whip element and the circuit ground, so the ground connection is just as=
> > much part of the antenna as the whip element itself is. Cle= arly, an
> > electrically quiet ground is needed for the active= whip, whether this is
> > provided by the coax feeder or a sepa= rate local ground connection.
>
> Years ago I built a simple= MPF-102 active whip into a gutted VHF coil enclosure
> of a NMO mo= bile antenna. I quickly noticed the antenna performed much better
>= when mounted on a vehicle roof than when mounted on a mast. Even when the= whip
> was elevated up to 10 meters above the vehicle the roof mou= nt received much better.
>
> As for the optical link, I attem= pted to link a remote VLF-3 by IR back to the
> shack. I never got= that to work very well but I feel sure someone that knows
> what= they are doing could perfect it.
>
> Dex
>
=
Hotmail: Free, trusted and rich email servic= e. Get it now. =3D --_17ba67a4-c08f-42fb-91bb-10d70bad56d0_--