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=-1.9 required=5.0 tests=BAYES_00,DNS_FROM_AHBL_RHSBL, HTML_40_50,HTML_MESSAGE 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 tAJDuG51005124 for ; Thu, 19 Nov 2015 14:56:16 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1ZzPds-0001Jn-AV for rs_out_1@blacksheep.org; Thu, 19 Nov 2015 13:52:52 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1ZzPdr-0001Je-UW for rsgb_lf_group@blacksheep.org; Thu, 19 Nov 2015 13:52:51 +0000 Received: from mail-wm0-f52.google.com ([74.125.82.52]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES128-GCM-SHA256:128) (Exim 4.86) (envelope-from ) id 1ZzPcs-0007PB-RI for rsgb_lf_group@blacksheep.org; Thu, 19 Nov 2015 13:52:50 +0000 Received: by wmec201 with SMTP id c201so26628977wme.0 for ; Thu, 19 Nov 2015 05:51:34 -0800 (PST) X-DKIM-Result: Domain=gmail.com Result=Good and Known Domain DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; bh=ggvwhu2XEEFVFJqiGtVySLf4K4undMIusFf1kWwAkQ0=; b=gjjE7LqliI3D6SFX+svqY/5QuYAEL/t0HKp+zwrLHDU8zfpRtK9t/mWU+CRFVbZfPc yIV/MMX/GYrWKURFszfmGFC9uQPEt/JyAvPOJouUJRxZVloMWLH4A6rNT6HsRhUxA/S3 27t/DOch8VUL1vSzsc2fXx3pFhXD2KN/PqeNKFb5Ffl/pIzZ+zFWhbzI8IxGbdwZicqY uLieW/nDV9N3y2IgkCWmDRQhUE/MRmoSAQvxwPr7tdoXlImvI+LYVykqa1roY3LtSEL/ vYyX7xe5v8WYnPiHGgdbHB9LPFRcpP6jQCj80dcNb/ZhlKHkA+NbhK9b9jwPpYMTEgn7 2Jxw== MIME-Version: 1.0 X-Received: by 10.28.91.83 with SMTP id p80mr11343545wmb.87.1447941094545; Thu, 19 Nov 2015 05:51:34 -0800 (PST) Received: by 10.28.130.139 with HTTP; Thu, 19 Nov 2015 05:51:34 -0800 (PST) In-Reply-To: <85DEAEE9B22C448CAB7794EAA388CF23@gnat> References: <1729369062.20151119120030@chriswilson.tv> <1C735FA296594DF897C48882843B0EB7@gnat> <85DEAEE9B22C448CAB7794EAA388CF23@gnat> Date: Thu, 19 Nov 2015 13:51:34 +0000 Message-ID: From: Andy Talbot To: rsgb_lf_group@blacksheep.org X-Scan-Signature: 74b370a313f780c8b04cdb625468086b Subject: Re: LF: Re: Antenna relays Content-Type: multipart/alternative; boundary=001a11443810989fb30524e50e24 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: 5173 --001a11443810989fb30524e50e24 Content-Type: text/plain; charset=UTF-8 When LF transmission is under way, the voltage will appear across the O/C contacts used to bring the HF feeder into operation. I suppose the current may have been what destroyed my reeds; first slightly melting the closed contacts, then vaporising some metal that created an arc inside and cascaded to destroy the whole thing 'jnt On 19 November 2015 at 13:42, Alan Melia wrote: > Hi Andy > Surely the voltage will not appear across the contacts, though I agree > contacts to activating coil might be a problem. > > Yes reeds area problem because I think of the reed material. I only used > them (from Coto) at low levels on ATE. I did have some rated in the kV > range but not taking much current. > > Alan > G3NYK > > ----- Original Message ----- > *From:* Andy Talbot > *To:* rsgb_lf_group@blacksheep.org > *Sent:* Thursday, November 19, 2015 12:44 PM > *Subject:* Re: LF: Re: Antenna relays > > 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 >>> >>> >>> >> >> > --001a11443810989fb30524e50e24 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
When LF transmission is under way, the voltage will appear= across the O/C contacts used to bring the HF feeder into operation.
I suppose the current may have been what destroyed my reeds; f= irst slightly melting the closed contacts, then vaporising some metal that = created an arc inside and cascaded to destroy the whole thing

<= /div>
'jnt


On 19 November 2015 at 13:42, Alan Melia <al= an.melia@btinternet.com> wrote:
Hi Andy
Surely the voltage will not appear acr= oss the=20 contacts, though I agree contacts to activating coil might be a=20 problem.
=C2=A0
Yes reeds area problem because I think= of the reed=20 material. I only used them (from Coto) at low levels on ATE.=C2=A0 I did ha= ve=20 some rated in the kV range but not taking much current.
=C2=A0
Alan
G3NYK
----- Original Message -----
From:=20 Andy=20 Talbot
Sent: Thursday, November 19, 2015 1= 2:44=20 PM
Subject: Re: LF: Re: Antenna relays=

Alan -=C2=A0
You're forgetting the loading coil has to be switched out when u= sing the=20 loop at HF, so the relay has to withstand the full RF voltage when using = it as=20 a vertical at LF/MF. =C2=A0=C2=A0

So you'll need a vacuum relay with a contacts rated at something= like=20 10kV. The current will only be an amp or so. =C2=A0 I tried this once usi= ng FR=20 / Crydom reed relays that were certainly rated at that sort of voltage.= =C2=A0=20 Trouble was that rating was DC.=C2=A0 At 137kHz it died with a flash from= =20 inside and melted contacts as soon as a decent amount of RF was applied.= =20 =C2=A0=C2=A0

A knife switch on a ceramic former would probably work, otherwise fi= nd=20 someone working for=C2=A0
NatGrid and try to get a 33 or 132kV contactor :-)


Andy =C2=A0G4JNT


On 19 November 2015 at 12:24, Alan Melia <alan.melia@btinternet.com> wrote:
Hi Chris I dont think the relay typ= e is too significant at=20 these frequencies. The important thing is its contacts should be able t= o=20 carry the current. It is at a low impedance point so the voltages shoul= d not=20 be excessive.=C2=A0 Even an open frame style intended for switching 20 = to=20 30A of 230v would be worth trying (I am sure you have a bin-full or two= of=20 those lying around :-))=C2=A0 ).......the old-timers used knife switche= s at=20 these frequencies :-))

Alan
G3NYK

----- Original Messa= ge=20 ----- From: "Chris Wilson" <chris@chriswilson.tv>
To: <rsgb_lf_group@bl= acksheep.org>
Sent: Thursday,=20 November 19, 2015 12:00 PM
Subject: LF: Antenna relays


19 November 2015


I am = currently running a=20 bottom strapped windowed ladder line feeder to
my=C2=A0=20 horizontal=C2=A0 quad=C2=A0 loop=C2=A0 as=C2=A0 the=C2=A0 vertical fo= r LF,=20 the loop as the
capacitive=C2=A0 top hat. It means I am unable to = use=20 it for HF though. I am
wondering if I might add a remote switched = relay=20 at the bottom of the
ladder line, so it has two states. One connec= ts my=20 co ax feeder to the
ladder=C2=A0 line=C2=A0 with=C2=A0 the=C2=A0 b= ottom=20 strapped together. the other opens the
strap and connects the 2 le= gs to=20 a balun and then my co as feed line.

Given=C2=A0 the voltages= =20 involved at LF, what sort of relay would I need to
be looking at?= =20 Thanks.



--=20


Best regards,
Chris=C2=A0 2E0ILY=C2=A0 =C2=A0 =C2=A0 = =C2=A0=20 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0=20 =C2=A0mailto:chris@chriswilson.tv





=

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