Return-Path: X-Spam-DCC: paranoid 1181; Body=2 Fuz1=2 Fuz2=2 X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=-0.2 required=5.0 tests=BAYES_00,DNS_FROM_AHBL_RHSBL, HTML_40_50,HTML_MESSAGE,RATWARE_GECKO_BUILD autolearn=no version=3.1.3 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by paranoid.lipkowski.org (8.13.7/8.13.7) with ESMTP id tAJEM1Ur005316 for ; Thu, 19 Nov 2015 15:22:01 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1ZzQ2o-0001nM-Pf for rs_out_1@blacksheep.org; Thu, 19 Nov 2015 14:18:38 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1ZzQ2o-0001nD-Ax for rsgb_lf_group@blacksheep.org; Thu, 19 Nov 2015 14:18:38 +0000 Received: from mout01.posteo.de ([185.67.36.65]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.86) (envelope-from ) id 1ZzQ1k-0007ch-HW for rsgb_lf_group@blacksheep.org; Thu, 19 Nov 2015 14:18:37 +0000 Received: from dovecot03.posteo.de (dovecot03.posteo.de [172.16.0.13]) by mout01.posteo.de (Postfix) with ESMTPS id BD48320A23 for ; Thu, 19 Nov 2015 15:17:20 +0100 (CET) Received: from mail.posteo.de (localhost [127.0.0.1]) by dovecot03.posteo.de (Postfix) with ESMTPSA id 3p1jkm4xVqz5vND for ; Thu, 19 Nov 2015 15:17:20 +0100 (CET) Message-ID: <564DD9F0.3020005@posteo.de> Date: Thu, 19 Nov 2015 15:17:20 +0100 From: DK7FC 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: <1729369062.20151119120030@chriswilson.tv> <1C735FA296594DF897C48882843B0EB7@gnat> In-Reply-To: X-Scan-Signature: 72f3686d3f5e154c987315e88c667a5f Subject: Re: LF: Re: Antenna relays Content-Type: multipart/alternative; boundary="------------080209060803080409030406" 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-Scanned-By: MIMEDefang 2.56 on 10.1.3.10 Status: O X-Status: X-Keywords: X-UID: 5177 This is a multi-part message in MIME format. --------------080209060803080409030406 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Chris, Yes, HV relays for DC or 50 Hz may not work properly: https://www.youtube.com/watch?v=hIkNY5xjy5k 73, Stefan Am 19.11.2015 13:44, schrieb Andy Talbot: > Alan - > You're forgetting the loading coil has to be switched out when using > the loop at HF, so the relay has to withstand the full RF voltage when > using it as a vertical at LF/MF. > > So you'll need a vacuum relay with a contacts rated at something like > 10kV. The current will only be an amp or so. I tried this once using > FR / Crydom reed relays that were certainly rated at that sort of > voltage. Trouble was that rating was DC. At 137kHz it died with a > flash from inside and melted contacts as soon as a decent amount of RF > was applied. > > A knife switch on a ceramic former would probably work, otherwise find > someone working for > NatGrid and try to get a 33 or 132kV contactor :-) > > > Andy G4JNT > > > On 19 November 2015 at 12:24, Alan Melia > wrote: > > Hi Chris I dont think the relay type is too significant at these > frequencies. The important thing is its contacts should be able to > carry the current. It is at a low impedance point so the voltages > should not be excessive. Even an open frame style intended for > switching 20 to 30A of 230v would be worth trying (I am sure you > have a bin-full or two of those lying around :-)) ).......the > old-timers used knife switches at these frequencies :-)) > > Alan > G3NYK > > ----- Original Message ----- From: "Chris Wilson" > > > To: > > Sent: Thursday, November 19, 2015 12:00 PM > Subject: LF: Antenna relays > > > 19 November 2015 > > > I am currently running a bottom strapped windowed ladder line > feeder to > my horizontal quad loop as the vertical for LF, the loop > as the > capacitive top hat. It means I am unable to use it for HF > though. I am > wondering if I might add a remote switched relay at the bottom > of the > ladder line, so it has two states. One connects my co ax > feeder to the > ladder line with the bottom strapped together. the other > opens the > strap and connects the 2 legs to a balun and then my co as > feed line. > > Given the voltages involved at LF, what sort of relay would I > need to > be looking at? Thanks. > > > > -- > > > Best regards, > Chris 2E0ILY > mailto:chris@chriswilson.tv > > > > > --------------080209060803080409030406 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: 8bit Chris,

Yes, HV relays for DC or 50 Hz may not work properly: https://www.youtube.com/watch?v=hIkNY5xjy5k
73, Stefan

Am 19.11.2015 13:44, schrieb Andy Talbot:
Alan - 
You're forgetting the loading coil has to be switched out when using the loop at HF, so the relay has to withstand the full RF voltage when using it as a vertical at LF/MF.   

So you'll need a vacuum relay with a contacts rated at something like 10kV. The current will only be an amp or so.   I tried this once using FR / Crydom reed relays that were certainly rated at that sort of voltage.  Trouble was that rating was DC.  At 137kHz it died with a flash from inside and melted contacts as soon as a decent amount of RF was applied.   

A knife switch on a ceramic former would probably work, otherwise find someone working for 
NatGrid and try to get a 33 or 132kV contactor :-)


Andy  G4JNT


On 19 November 2015 at 12:24, Alan Melia <alan.melia@btinternet.com> wrote:
Hi Chris I dont think the relay type is too significant at these frequencies. The important thing is its contacts should be able to carry the current. It is at a low impedance point so the voltages should not be excessive.  Even an open frame style intended for switching 20 to 30A of 230v would be worth trying (I am sure you have a bin-full or two of those lying around :-))  ).......the old-timers used knife switches at these frequencies :-))

Alan
G3NYK

----- Original Message ----- From: "Chris Wilson" <chris@chriswilson.tv>
To: <rsgb_lf_group@blacksheep.org>
Sent: Thursday, November 19, 2015 12:00 PM
Subject: LF: Antenna relays


19 November 2015


I am currently running a bottom strapped windowed ladder line feeder to
my  horizontal  quad  loop  as  the  vertical for LF, the loop as the
capacitive  top hat. It means I am unable to use it for HF though. I am
wondering if I might add a remote switched relay at the bottom of the
ladder line, so it has two states. One connects my co ax feeder to the
ladder  line  with  the  bottom strapped together. the other opens the
strap and connects the 2 legs to a balun and then my co as feed line.

Given  the voltages involved at LF, what sort of relay would I need to
be looking at? Thanks.



--


Best regards,
Chris  2E0ILY                           mailto:chris@chriswilson.tv





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