Hello Minto,
my old 136kHz antenna seems pretty similar to yours. If I remind well the
antenna capacitance was slightly more (420pF) and the loss a bit less in winter
(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
voltage. I had about 50% of the loading coil at the top of the vertical
section, 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: [email protected] [[email protected]]
namens Minto Witteveen [[email protected]]
Verzonden: maandag 25 juli 2011 21:34
Aan: [email protected]
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 is
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: [email protected]
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 DX
= OH1TN).
So don't dispair.
73, Rik ON7YD - OR7T
|
