Message-ID: <85DEAEE9B22C448CAB7794EAA388CF23@gnat>
From: "Alan Melia" <alan.melia@btinternet.com>
To: <rsgb_lf_group@blacksheep.org>
References: <1729369062.20151119120030@chriswilson.tv><1C735FA296594DF897C48882843B0EB7@gnat> <CAA8k23QJA9cywxQHScDv8egMpCLqope-MgEv7Um3D5SG4tGS=w@mail.gmail.com>
Date: Thu, 19 Nov 2015 13:42:07 -0000
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Subject: Re: LF: Re: Antenna relays
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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 -----=20
  From: Andy Talbot=20
  To: rsgb_lf_group@blacksheep.org=20
  Sent: Thursday, November 19, 2015 12:44 PM
  Subject: Re: LF: Re: Antenna relays


  Alan -=20
  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.  =20


  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.  =20


  A knife switch on a ceramic former would probably work, otherwise find =
someone working for=20
  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.



      --=20


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








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<BODY bgColor=3D#ffffff>
<DIV><FONT size=3D2 face=3DArial>Hi Andy</FONT></DIV>
<DIV><FONT size=3D2 face=3DArial>Surely the voltage will not appear =
across the=20
contacts, though I agree contacts to activating coil might be a=20
problem.</FONT></DIV>
<DIV><FONT size=3D2 face=3DArial></FONT>&nbsp;</DIV>
<DIV><FONT size=3D2 face=3DArial>Yes reeds area problem because I think =
of the reed=20
material. I only used them (from Coto) at low levels on ATE.&nbsp; I did =
have=20
some rated in the kV range but not taking much current.</FONT></DIV>
<DIV><FONT size=3D2 face=3DArial></FONT>&nbsp;</DIV>
<DIV><FONT size=3D2 face=3DArial>Alan</FONT></DIV>
<DIV><FONT size=3D2 face=3DArial>G3NYK</FONT></DIV>
<BLOCKQUOTE=20
style=3D"BORDER-LEFT: #000000 2px solid; PADDING-LEFT: 5px; =
PADDING-RIGHT: 0px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px"=20
dir=3Dltr>
  <DIV style=3D"FONT: 10pt arial">----- Original Message ----- </DIV>
  <DIV=20
  style=3D"FONT: 10pt arial; BACKGROUND: #e4e4e4; font-color: =
black"><B>From:</B>=20
  <A title=3Dandy.g4jnt@gmail.com =
href=3D"mailto:andy.g4jnt@gmail.com">Andy=20
  Talbot</A> </DIV>
  <DIV style=3D"FONT: 10pt arial"><B>To:</B> <A =
title=3Drsgb_lf_group@blacksheep.org=20
  =
href=3D"mailto:rsgb_lf_group@blacksheep.org">rsgb_lf_group@blacksheep.org=
</A>=20
  </DIV>
  <DIV style=3D"FONT: 10pt arial"><B>Sent:</B> Thursday, November 19, =
2015 12:44=20
  PM</DIV>
  <DIV style=3D"FONT: 10pt arial"><B>Subject:</B> Re: LF: Re: Antenna =
relays</DIV>
  <DIV><BR></DIV>
  <DIV dir=3Dltr>Alan -&nbsp;
  <DIV>You're forgetting the loading coil has to be switched out when =
using 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. &nbsp;&nbsp;</DIV>
  <DIV><BR></DIV>
  <DIV>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. &nbsp; I tried this once =
using FR=20
  / Crydom reed relays that were certainly rated at that sort of =
voltage.&nbsp;=20
  Trouble was that rating was DC.&nbsp; At 137kHz it died with a flash =
from=20
  inside and melted contacts as soon as a decent amount of RF was =
applied.=20
  &nbsp;&nbsp;</DIV>
  <DIV><BR></DIV>
  <DIV>A knife switch on a ceramic former would probably work, otherwise =
find=20
  someone working for&nbsp;</DIV>
  <DIV>NatGrid and try to get a 33 or 132kV contactor :-)</DIV>
  <DIV><BR></DIV>
  <DIV><BR></DIV>
  <DIV>Andy &nbsp;G4JNT</DIV>
  <DIV><BR></DIV>
  <DIV class=3Dgmail_extra><BR>
  <DIV class=3Dgmail_quote>On 19 November 2015 at 12:24, Alan Melia =
<SPAN=20
  dir=3Dltr>&lt;<A href=3D"mailto:alan.melia@btinternet.com"=20
  target=3D_blank>alan.melia@btinternet.com</A>&gt;</SPAN> wrote:<BR>
  <BLOCKQUOTE=20
  style=3D"BORDER-LEFT: #ccc 1px solid; MARGIN: 0px 0px 0px 0.8ex; =
PADDING-LEFT: 1ex"=20
  class=3Dgmail_quote>Hi Chris I dont think the relay type is too =
significant at=20
    these frequencies. The important thing is its contacts should be =
able to=20
    carry the current. It is at a low impedance point so the voltages =
should not=20
    be excessive.&nbsp; 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 :-))&nbsp; ).......the old-timers used knife =
switches at=20
    these frequencies :-))<BR><BR>Alan<BR>G3NYK<BR><BR>----- Original =
Message=20
    ----- From: "Chris Wilson" &lt;<A =
href=3D"mailto:chris@chriswilson.tv"=20
    target=3D_blank>chris@chriswilson.tv</A>&gt;<BR>To: &lt;<A=20
    href=3D"mailto:rsgb_lf_group@blacksheep.org"=20
    target=3D_blank>rsgb_lf_group@blacksheep.org</A>&gt;<BR>Sent: =
Thursday,=20
    November 19, 2015 12:00 PM<BR>Subject: LF: Antenna =
relays<BR><BR><BR>
    <BLOCKQUOTE=20
    style=3D"BORDER-LEFT: #ccc 1px solid; MARGIN: 0px 0px 0px 0.8ex; =
PADDING-LEFT: 1ex"=20
    class=3Dgmail_quote>19 November 2015<BR><BR><BR>I am currently =
running a=20
      bottom strapped windowed ladder line feeder to<BR>my&nbsp;=20
      horizontal&nbsp; quad&nbsp; loop&nbsp; as&nbsp; the&nbsp; vertical =
for LF,=20
      the loop as the<BR>capacitive&nbsp; top hat. It means I am unable =
to use=20
      it for HF though. I am<BR>wondering if I might add a remote =
switched relay=20
      at the bottom of the<BR>ladder line, so it has two states. One =
connects my=20
      co ax feeder to the<BR>ladder&nbsp; line&nbsp; with&nbsp; =
the&nbsp; bottom=20
      strapped together. the other opens the<BR>strap and connects the 2 =
legs to=20
      a balun and then my co as feed line.<BR><BR>Given&nbsp; the =
voltages=20
      involved at LF, what sort of relay would I need to<BR>be looking =
at?=20
      Thanks.<BR><BR><BR><SPAN class=3DHOEnZb><FONT =
color=3D#888888><BR>--=20
      <BR><BR><BR>Best regards,<BR>Chris&nbsp; 2E0ILY&nbsp; &nbsp; =
&nbsp; &nbsp;=20
      &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;=20
      &nbsp;mailto:<A href=3D"mailto:chris@chriswilson.tv"=20
      =
target=3D_blank>chris@chriswilson.tv</A><BR><BR><BR></FONT></SPAN></BLOCK=
QUOTE><BR><BR></BLOCKQUOTE></DIV><BR></DIV></DIV></BLOCKQUOTE></BODY></HT=
ML>

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