Date: Fri, 25 Jan 2019 15:29:31 +0000 (GMT)
From: Michael WALTERS <michael.walters26@ntlworld.com>
To: rsgb_lf_group@blacksheep.org, DK7FC <selberdenken@posteo.de>
Message-ID: <114672840.240476.1548430171737@mail2.virginmedia.com>
In-Reply-To: <5C4B1BD5.6010404@posteo.de>
References: <D98C1CCC49324084BCF225E22F521809@DELL4>
 <1UTCTNxG9H.5T3bfQF3xD0@optiplex980-pc>
 <9C9C8088-AD45-4DDF-BD7E-66D13F0D835C@md.metrocast.net>
 <CANA3B6VBpQ0G92wmOniO3GvedBbaOoBuMuFPW1Fs743B8VCvpw@mail.gmail.com>
 <5C4B1BD5.6010404@posteo.de>
MIME-Version: 1.0
Importance: Medium
Subject: Re: LF: TXing WSPR/MF on an indoor loop
Content-Type: multipart/alternative; 
	boundary="----=_Part_240475_757752561.1548430171735"
Sender: owner-rsgb_lf_group@blacksheep.org
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org

------=_Part_240475_757752561.1548430171735
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit

Stefen I found the same effect with Wima, I had some large value Mica's and paralled for value - this then was very stable, Mike G3JVL

> On 25 January 2019 at 14:23 DK7FC <selberdenken@posteo.de mailto:selberdenken@posteo.de > wrote:
> 
> 
>     Hi MF,
> 
>     A few days ago i took some RF litz wire and built a loop that is now
>     hanging on the wall inside my home, just 1m besides the bed :-) (no XYL
>     here spoiling the fun). The loop is beaming to about 150/330 deg.
> 
>     After playing some days on 160m (an unusual high frequency, witch feels
>     very strange. And the band is full of unknown callsigns!!) i did now
>     move down to more or less low frequencies, the 630m band!
> 
>     About 10 nF is needed to series resonate the loop. It has about 2m x 2m
>     of size. The antenna current is not stable because the WIMA FKP-1
>     capacitor becomes warm during the 2 minute WSPR sequence. But the
>     maximum current in the loop is 14 A. That explains why the cap becomes
>     warm. A small parallel variable capacitor tunes to resonance. It is
>     tuned so that the upheating capacitor runs into the resonance point in
>     the middle of the WSPR sequence, then it runs out of the resonance by
>     upheating further. It can cool down during the following quiet periods..
> 
>     14A into a 4 square meter loop at 475.7 kHz, how much ERP is that? The
>     PA consumes about 3.5 A at 13.8V, i.e. about 50 W.
> 
>     The system will run over the weekend, even during daylight. The signal
>     generator is a Raspi which will have no internet connectivity from now
>     on, so let's hope the time offset stays inside the accepted range for
>     this experiment.
> 
>     What will the best distance be? So far the band is closed but i'm
>     optimistic to crack the 1000 km distance with this QRP setup.
> 
>     73, Stefan
> 

------=_Part_240475_757752561.1548430171735
MIME-Version: 1.0
Content-Type: text/html; charset=UTF-8
Content-Transfer-Encoding: quoted-printable

<!DOCTYPE html>
<html><head>
    <meta charset=3D"UTF-8">
</head><body>Stefen I found the same effect with Wima,   I had some large v=
alue Mica&#39;s and paralled for value - this then was very stable, Mike G3=
JVL<br><blockquote type=3D"cite">On 25 January 2019 at 14:23 DK7FC &#60;<a =
href=3D"mailto:selberdenken@posteo.de">selberdenken@posteo.de</a>&#62; wrot=
e:<br><br><br>Hi MF,<br><br>A few days ago i took some RF litz wire and bui=
lt a loop that is now <br>hanging on the wall inside my home, just 1m besid=
es the bed :-) (no XYL <br>here spoiling the fun). The loop is beaming to a=
bout 150/330 deg.<br><br>After playing some days on 160m (an unusual high f=
requency, witch feels <br>very strange. And the band is full of unknown cal=
lsigns!!) i did now <br>move down to more or less low frequencies, the 630m=
 band!<br><br>About 10 nF is needed to series resonate the loop. It has abo=
ut 2m x 2m <br>of size. The antenna current is not stable because the WIMA =
FKP-1 <br>capacitor becomes warm during the 2 minute WSPR sequence. But the=
 <br>maximum current in the loop is 14 A. That explains why the cap becomes=
 <br>warm. A small parallel variable capacitor tunes to resonance. It is <b=
r>tuned so that the upheating capacitor runs into the resonance point in <b=
r>the middle of the WSPR sequence, then it runs out of the resonance by <br=
>upheating further. It can cool down during the following quiet periods..<b=
r><br>14A into a 4 square meter loop at 475.7 kHz, how much ERP is that? Th=
e <br>PA consumes about 3.5 A at 13.8V, i.e. about 50 W.<br><br>The system =
will run over the weekend, even during daylight. The signal <br>generator i=
s a Raspi which will have no internet connectivity from now <br>on, so let&=
#39;s hope the time offset stays inside the accepted range for <br>this exp=
eriment.<br><br>What will the best distance be? So far the band is closed b=
ut i&#39;m <br>optimistic to crack the 1000 km distance with this QRP setup=
.<br><br>73, Stefan</blockquote></body></html>
=20
------=_Part_240475_757752561.1548430171735--