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From: Andy Talbot <andy.g4jnt@gmail.com>
Date: Mon, 24 Jul 2017 16:40:08 +0100
Message-ID: <CAA8k23S6SAQYNB4QoqzRCZFdQTwZT6ttB5obUKbAQuiEaWgwfw@mail.gmail.com>
To: rsgb_lf_group@blacksheep.org
Subject: Re: LF: Re: Antenna change over relay question
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Digressing slightly, but a parallel warning...

I once hot disconnected  a BNC plug carrying 700 Watts of RF (Low Z,
transmitter output) .    As the contact broke it generated  a plasma arc
that shot out of the BNC plug that I dropped in shock.  It continued to
burn, vaporising the centre pin of the BNC, and burning a mark into the
floor surface I'd dropped it onto.

'jnt


On 24 July 2017 at 15:58, Chris Wilson <dead.fets@gmail.com> wrote:

> Hello Ian,
>
> You  have me worried now, as does Andy with his last post, the thought
> of  putting  a kilowatt into the RX antenna socket of my 590 is not a
> pleasant or cheap one... Hmmm.
>
>
>
> Monday, July 24, 2017, 3:40:38 PM, you wrote:
>
> > Hi Chris/Stefan
>
> > Loosely connected to your question, I wanted to switch my Inv L between
> > LF/MF Variometer/loading coils and HF Auto remote tuner remotely, i.e
> 120'
> > away from the shack.
>
> > Every relay I tried had insulation break down and contact arc over. Only
> > running 360 W at MF and 300 at LF.
>
> > My solution was to fabricate a 3 position Knife type switch operated via
> a
> > Servo motor to switch the antennae and a standard 20 Amp Rated relay for
> the
> > RF inputs to the Tuner and Variometers.
>
> > No more insulation break down or arc over. The contacts are mounted on
> Old
> > Eddystone porcelain insulators.
>
> > I would be interested to know how the relay holds up with 1 kW at 136
> kHz.
>
> > 73
>
> > Ian G4GIR
>
>
>
>
>
>
> --
> Best regards,
>  Chris                            mailto:dead.fets@gmail.com
>
>
>

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<div dir=3D"ltr"><div>Digressing slightly, but a parallel warning...</div><=
div><br></div>I once hot disconnected =C2=A0a BNC plug carrying 700 Watts o=
f RF (Low Z, transmitter output) . =C2=A0 =C2=A0As the contact broke it gen=
erated =C2=A0a plasma arc that shot out of the BNC plug that I dropped in s=
hock.=C2=A0 It continued to burn, vaporising the centre pin of the BNC, and=
 burning a mark into the floor surface I&#39;d dropped it onto.<div><br></d=
iv><div>&#39;jnt</div><div><br></div></div><div class=3D"gmail_extra"><br><=
div class=3D"gmail_quote">On 24 July 2017 at 15:58, Chris Wilson <span dir=
=3D"ltr">&lt;<a href=3D"mailto:dead.fets@gmail.com" target=3D"_blank">dead.=
fets@gmail.com</a>&gt;</span> wrote:<br><blockquote class=3D"gmail_quote" s=
tyle=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hell=
o Ian,<br>
<br>
You=C2=A0 have me worried now, as does Andy with his last post, the thought=
<br>
of=C2=A0 putting=C2=A0 a kilowatt into the RX antenna socket of my 590 is n=
ot a<br>
pleasant or cheap one... Hmmm.<br>
<br>
<br>
<br>
Monday, July 24, 2017, 3:40:38 PM, you wrote:<br>
<br>
&gt; Hi Chris/Stefan<br>
<br>
&gt; Loosely connected to your question, I wanted to switch my Inv L betwee=
n<br>
&gt; LF/MF Variometer/loading coils and HF Auto remote tuner remotely, i.e =
120&#39;<br>
&gt; away from the shack.<br>
<br>
&gt; Every relay I tried had insulation break down and contact arc over. On=
ly<br>
&gt; running 360 W at MF and 300 at LF.<br>
<br>
&gt; My solution was to fabricate a 3 position Knife type switch operated v=
ia a<br>
&gt; Servo motor to switch the antennae and a standard 20 Amp Rated relay f=
or the<br>
&gt; RF inputs to the Tuner and Variometers.<br>
<br>
&gt; No more insulation break down or arc over. The contacts are mounted on=
 Old<br>
&gt; Eddystone porcelain insulators.<br>
<br>
&gt; I would be interested to know how the relay holds up with 1 kW at 136 =
kHz.<br>
<br>
&gt; 73<br>
<br>
&gt; Ian G4GIR<br>
<span class=3D"HOEnZb"><font color=3D"#888888"><br>
<br>
<br>
<br>
<br>
<br>
--<br>
Best regards,<br>
=C2=A0Chris=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 mailto:<a href=3D"mailto:dead.fets@gmail=
.com">dead.fets@gmail.com</a><br>
<br>
<br>
</font></span></blockquote></div><br></div>

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