Message-ID: <15d76cac1c1.marcocadeddu@tin.it>
Date: Tue, 25 Jul 2017 00:49:45 +0200 (CEST)
From: "marcocadeddu@tin.it" <marcocadeddu@tin.it>
To:  <rsgb_lf_group@blacksheep.org>
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Subject: R: Re: LF: Re: Antenna change over relay question
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Hello LF & VLF,

I posted my solution, but the attached picture of my ATU for LF/MF was 
too much for blacksheep..
In my ATU I have to switch in and out the LF base coil 
of my antenna and change the matching transformer for LF and MF.
I made it with 2 vacuum relays: the switching of XFMR is made with a 
Siemens VR311 (rated at 10kV 20A) the coil switching is made with a 
Jennings RE6 which is rated at 25kV 25A. Both are of course surplus 
purchases.. but are easy to find on e-bay. For new relays purchase, 
don't forget, if still valid, that Kilovac was used to sell a small 
number of relays each year to HAM operators with special (affordable.. 
) price: if you wish to have brand new units a check on their web pages 
is worth ;-)

73 Marco IK1HSS

----Messaggio originale----
Da: andy.g4jnt@gmail.com
Data: 24-lug-2017 17.40
A: <rsgb_lf_group@blacksheep.org>
Ogg: Re: LF: Re: Antenna change over relay question

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
>
>
>