From: Rik Strobbe <Rik.Strobbe@fys.kuleuven.be>
To: "rsgb_lf_group@blacksheep.org" <rsgb_lf_group@blacksheep.org>
Date: Mon, 25 Jul 2011 22:40:38 +0200
Thread-Topic: Re: DL6NN on 137
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Hello Minto,

my old 136kHz antenna seems pretty similar to yours. If I remind well the a=
ntenna capacitance was slightly more (420pF) and the loss a bit less in win=
ter (130 Ohm) but higher in summer (up to 170 Ohm).
The maximum output power was 450W, good for 1.85 A antenna current and just=
 over 5kV antenna voltage.
As long as the antenna was dry I never had any problems with the antenna vo=
ltage. I had about 50% of the loading coil at the top of the vertical secti=
on, so the vertical section had "only" 2.5kV.
It seems a good idea to keep the hight voltage outdoor. Maybe you can put a=
 large fixed coil outside and just have a small variometer for daily tuning=
 inside. This will also reduce the losses.

73, Rik  ON7YD - OR7T

________________________________________
Van: owner-rsgb_lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.org=
] namens Minto Witteveen [minto.witteveen@gmail.com]
Verzonden: maandag 25 juli 2011 21:34
Aan: rsgb_lf_group@blacksheep.org
Onderwerp: LF: Re: DL6NN on 137

Hi Rik,
Thanks for the heads-up.
I think your antenna is better than mine, but possibly not by much. I do
have another concern however, and that is the high voltage at the antenna.
The capacitance at 136 kHz is (measured) 390 pF. With a total system
impedance of 150 Ohm and 1 kW this translates to 7.7 kV!!
On 500 I already had some "interesting" phenomena  with 5 kV. The antenna i=
s
end-fed here in the shack in the attic.
So I will have a fire extinguisher at hand when tx-ing on 136..

Regards,
Minto pa3bca.

--------------------------------------------------------------------------
Ceterum censeo Carthaginem delendam esse
-----Original Message-----
From: Rik Strobbe
Sent: Sunday, July 24, 2011 20:51
To: rsgb_lf_group@blacksheep.org
Subject: RE: LF: DL6NN on 137

Minto,

I was active on 136kHz with a similar antenna (15m high, 25m long "lazy-L"
antenna) and in addition the losses were very high (abt. 130-160 Ohm).
Despite that I managed to work distances up to 1600km in regular CW (best D=
X
=3D OH1TN).
So don't dispair.

73, Rik  ON7YD - OR7T=