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Re: LF: LOPTs

To: [email protected]
Subject: Re: LF: LOPTs
From: Stefan Schäfer <[email protected]>
Date: Sun, 01 Apr 2012 23:47:12 +0200
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References: <CAHAQVWMHwxmWAPqTVxgdAK-h35BLbu5QOkD9eKEe37P=hAhkCg@mail.gmail.com>
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Hi Roger,

Well, they are not as suitable as i expected. Just a few kV can be generated and applied to the wire. But that's fine for local tests. I didn't measure the L but rather tried to find a resonance. I took two 1 nF capacitors and a 50 Ohm resistor in series to make an equivalent circuit of my antenna for tests in the shack. I built a class D PA out of the transformer, running at low input voltage and tried to find the resonance. But there was no clear resonance. The output waveform looks very different to a sine wave :-) Probably this is due to internal winding capacitances, no idea. At least i spend a lot of time and do not want to spend even more time on the LOPT project.
A few weeks ago i tried some local tests with WOLF10 and got a decode in 950m distance, which is close in the near field, so not really exciting. I just want to go on a bit with these tests but i won't go on much longer with the tests. The standard QRSS or DFCW or MFSK analog modes, readout by a human is just the best in my opinion.

73, Stefan



Am 01.04.2012 22:35, schrieb Roger Lapthorn:
Stefan et al,

Not being too familiar with LOPTs what inductance are the windings? Are there particular non-encapsulated types that would be more suitable for compact loading coils for lower powered 8.97kHz E-field TX antennas?

73s
Roger G3XBM

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