Message-ID: <4DC7158B.8090003@dsl.pipex.com>
Date: Sun, 08 May 2011 23:13:31 +0100
From: Chris Dillon <c.r.dillon@dsl.pipex.com>
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References: <4DC65644.701@talktalk.net>  <4DC6D9DA.3080801@dsl.pipex.com> <1304888225.1662.27.camel@gerhard-desktop> <4DC70AD5.7030102@iup.uni-heidelberg.de>
In-Reply-To: <4DC70AD5.7030102@iup.uni-heidelberg.de>
Subject: Re: LF: ZEVS transmission at 1800BST
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Hi Stefan, Gerhard, ELF
The pre-amp is your circuit, Stefan, with the input FET on the antenna=20
and connected through 10m of twisted pair. For normal VLF work I also=20
added a op amp to the output of the second FE. This rolls off=20
below1.3kHz and drives 30m of coax to my computer upstairs in the house=20
through two cheap 600 ohm line isolating transformers. The ZEVS signals=20
are doing well to get through the LF filtering. I haven't changed the=20
LPF in SL which is still set at 22kHz - the default settings for normal=20
VLF. The hum filter is switched on and significantly reduces the 50Hz=20
component.

73 Chris G3WCD

On 08/05/2011 22:27, Stefan Sch=C3=A4fer wrote:
> Hello Chris, Gerhard, ELF,
>
> I've also seen a stable trace at 82 Hz but not the frequency shifting=20
> transmission before. For some reasons there are various QRM levels=20
> here and i don't know the origin. Never mind and interesting to see=20
> something at all. Would be interesting to see what can be achieved=20
> with an ELF optimised crcuit...
>
> My SL settings include a 700 Hz LPF and the noiseblanker afterwards,=20
> using the usual VLF settings. The width of one FFT bin is at 11 mHz=20
> and the scroll rate is 1 pix/minute which seems to be a bit to slow. I=
=20
> will change to 30 sec/pix soon. I've switched on the "Paul Nicholsons=20
> hum filter" and set the hum frequency to 16 2/3 Hz to remove 50 Hz and=
=20
> 16 2/3 Hz harmonics of the German train power grid.
>
> Maybe a simple mains transformer allows a simple way to realise a LPF?
>
> 73, Stefan/DK7FC
>
> Am 08.05.2011 22:57, schrieb Gerhard Hickl:
>> Hi Chris, LF!
>>
>> Very interesting....I'm also using Stefan's E-probe and on 9khz ist's
>> very sensitive. My probe is more than 15m above ground and I'm also
>> trying to receive the ZEVS-transmissions. I have the window running
>> since a few days but nothing on screen here in JN88hl....
>>
>> I'm just using a low-pass filter with 1000Hz -3db point and the
>> noise-blanker afterwards. I wonder about your SL-settings.
>>
>> 73
>> OE3GHB
>> Gerhard
>>
>>
>>
>> Am Sonntag, den 08.05.2011, 18:58 +0100 schrieb Chris Dillon:
>>> Hi all - ZEVS transmission starting at 1800 BST received at IO92vf
>>> using a 'Stefan' pre-amp with a 1m probe about 3m high.
>>> Still transmitting a constant carrier on 82 Hz at 1857 BST. Wonder if
>>> they QSL reception reports?!
>>>
>>> 73 Chris G3WCD
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> On 08/05/2011 09:37, qrss wrote:
>>>> Stefan / LF
>>>>
>>>> Message commenced 0800UTC.
>>>>
>>>> Eddie
>>>>
>>>>
>>
>
>