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: [email protected]
Data: 24-lug-2017 17.40
A: <[email protected]>
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 <[email protected]> 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:[email protected]
>
>
>
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