X-GM-THRID: 1229634966541823928 X-Gmail-Labels: lowfer,rsgb lf Delivered-To: daveyxm@gmail.com Received: by 10.115.73.6 with SMTP id a6cs311wal; Wed, 28 Feb 2007 06:03:07 -0800 (PST) Received: by 10.67.26.7 with SMTP id d7mr702572ugj.1172671286228; Wed, 28 Feb 2007 06:01:26 -0800 (PST) Return-Path: Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mx.google.com with ESMTP id o24si608690ugd.2007.02.28.06.01.25; Wed, 28 Feb 2007 06:01:26 -0800 (PST) Received-SPF: neutral (google.com: 193.82.116.20 is neither permitted nor denied by best guess record for domain of owner-rsgb_lf_group@blacksheep.org) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1HMPG5-0005Yu-M5 for rs_out_1@blacksheep.org; Wed, 28 Feb 2007 13:54:17 +0000 Received: from [193.82.59.130] (helo=relay2.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1HMPG5-0005Yl-38 for rsgb_lf_group@blacksheep.org; Wed, 28 Feb 2007 13:54:17 +0000 Received: from sccrmhc12.comcast.net ([63.240.77.82]) by relay2.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1HMPG0-0004eo-8J for rsgb_lf_group@blacksheep.org; Wed, 28 Feb 2007 13:54:16 +0000 Received: from airportterminal (c-71-234-114-84.hsd1.ct.comcast.net[71.234.114.84]) by comcast.net (sccrmhc12) with SMTP id <2007022813540401200chfise>; Wed, 28 Feb 2007 13:54:05 +0000 Message-ID: <001701c75b40$54bc2740$6901a8c0@AIRPORTTERMINAL> From: "Jay Rusgrove" To: References: <002101c75b37$1e370680$6401a8c0@JAYTERMINAL> Date: Wed, 28 Feb 2007 08:57:05 -0500 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2600.0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 X-Spam-Score: 0.4 (/) X-Spam-Report: autolearn=disabled,AWL=0.356,HTML_MESSAGE=0.001 Subject: LF: Re: [Lowfer] Protecting E probe antennas in near field of LF TX antennas Content-Type: multipart/alternative; boundary="----=_NextPart_000_0014_01C75B16.6B9232E0" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.5 required=5.0 tests=HTML_20_30,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 Status: O X-Status: X-Keywords: X-UID: 7077 This is a multi-part message in MIME format. ------=_NextPart_000_0014_01C75B16.6B9232E0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Dave I have several ground mounted 1-meter e probe antennas (Amrad design but = with J310, no ferrite bead and NE-2 replaced with a 75 volt gas-filled = surge arrestor) located about 75 feet from my 1 watt ERP 137 kHz setup = and haven't suffered any failures...this with no external protection. = Not suggesting this is a good idea... just to note that they can be = pretty robust. =20 I did lose a CP666 or two (original device used in the Amrad antenna at = about $15 a copy) to lightning but since I switched to the J310 there = haven't been any failures. Probably because the J310s are cheap and I = have plenty in the junk box ;~) Jay W1VD / WD2XNS ----- Original Message -----=20 From: "Dave Brown" To: ; "Discussion of the Lowfer (US, = European, & UK) and MedFer bands" Sent: Wednesday, February 28, 2007 6:51 AM Subject: [Lowfer] Protecting E probe antennas in near field of LF TX = antennas > Has anyone done anything along the lines of the subject line using a > mechanical switch/relay arrangement? > I expect that any electronic method would add considerably to the > capacitance from the probe 'antenna' to ground so the best option > would seem to be to use something like the mechanical arrangement in > the old Dow-Key coax relays that had the 'isolated' receive side > contact. This will require a relay of some sort in the E probe that > operates to remove the protective earth only when on receive. I'm > still mulling over the best mechanical arrangement to implement this > scheme-all ideas most welcome. > 73 > Dave, ZL3FJ > _______________________________________________ > >From the Lowfer mailing list > Send messages to: Lowfer@mailman.qth.net > To sub/unsub visit: http://mailman.qth.net/mailman/listinfo/lowfer ------=_NextPart_000_0014_01C75B16.6B9232E0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Dave
 
I have several ground mounted 1-meter e = probe=20 antennas (Amrad design but with J310, no ferrite bead and NE-2 replaced = with a=20 75 volt gas-filled surge arrestor) located=20 about 75 feet from my 1 watt ERP 137 kHz setup and haven't suffered any=20 failures...this with no external protection. Not suggesting this is a = good=20 idea...  just to note that they can be pretty robust.=20  
 
I did lose a CP666 or two = (original device=20 used in the Amrad antenna at about $15 a copy) to lightning but since I = switched=20 to the J310 there haven't been any failures. Probably because = the=20 J310s are cheap and I have plenty in the junk box ;~)
 
Jay W1VD / WD2XNS
 
----- Original Message -----
From: "Dave Brown" <tractorb@ihug.co.nz>
To: = <rsgb_lf_group@blacksheep.org= >;=20 "Discussion of the Lowfer (US, European, &amp; UK) and = MedFer
bands"=20 <lowfer@mailman.qth.net>
= Sent:=20 Wednesday, February 28, 2007 6:51 AM
Subject: [Lowfer] Protecting E = probe=20 antennas in near field of LF TX antennas


> Has anyone done = anything along the lines of  the subject line using a
> = mechanical=20 switch/relay arrangement?
> I expect that any electronic method = would add=20 considerably to the
> capacitance from the probe 'antenna' to = ground so=20 the best option
> would seem to be to use something like the = mechanical=20 arrangement in
> the old Dow-Key coax relays that had the = 'isolated'=20 receive side
> contact. This will require a relay of some sort in = the E=20 probe that
> operates to remove the protective earth only when on=20 receive.  I'm
> still mulling over the best mechanical = arrangement to=20 implement this
> scheme-all ideas most welcome.
> 73
> = Dave,=20 ZL3FJ
> _______________________________________________
> = >From=20 the Lowfer mailing list
> Send messages to: Lowfer@mailman.qth.net
>= To=20 sub/unsub visit: http://mailman.qt= h.net/mailman/listinfo/lowfer
------=_NextPart_000_0014_01C75B16.6B9232E0--