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From: "mal hamilton" <g3kevmal@talktalk.net>
To: <rsgb_lf_group@blacksheep.org>
References: <CAA8k23Rn9WpQM3Ukf=cq5-bLmWy+o4SEsH2abf7cAX=BpLWExQ@mail.gmail.com> <op.v6k16ktpyzqh0k@pc-roelof> <033201ccbcab$5c5fe640$1502a8c0@Clemens04> <op.v6mtuugnyzqh0k@pc-roelof> <000901ccbcc4$42768fe0$c763afa0$@com> <4EECC1E8.4000806@iup.uni-heidelberg.de>
Date: Sun, 18 Dec 2011 10:25:18 -0000
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Subject: LF: Re: TX system at DK7FC, schematic
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Hi Stefan
Nice set up at ur station.
A couple of points ---
Your coil with a Q of 1000 seems very high and how high can a Q get ?
Your antenna is just a horizontal wire 70 metres long hanging between two
buildings 30 metres high. You have a vy good signal  for this simple
antenna.
I can see you resonate your 3mH coild with a motor driven variometer but how
do you match this to exactly 50 ohmz for a SWR of 1:1 to the TX
I can see your coil and transformer secondary are  in series to earth but no
adjustment for matching.
Maybe I have missed something
73 gl de mal/g3kev

----- Original Message -----
From: "Stefan Schäfer" <Stefan.Schaefer@iup.uni-heidelberg.de>
To: <rsgb_lf_group@blacksheep.org>
Cc: "Roman" <rw3adb@yandex.ru>
Sent: Saturday, December 17, 2011 4:23 PM
Subject: LF: TX system at DK7FC, schematic


> Hi Terry, LF,
>
> I want to add something to the TX/antenna matching discussion. There
> have often been querys about a schematic of my TX/PA system. So i
> finally took the time to draw it, how it looks in principle. It is just
> one example how it can be done of course. Maybe it helps to get further
> ideas how you can do it one your side.
>
>
http://dl.dropbox.com/u/19882028/LF/DK7FC_137kHz_TX_antenna_and_PA_schematic
.jpg
>
> Best 73, Stefan/DK7FC
>
>
> Am 17.12.2011 15:00, schrieb Terry GW0EZY:
> > First of all thanks to Andy for starting the Wellbrook discussion - it
has
> > been very useful for me.
> >
> > James - thanks for the information on the pros/cons of using Litz wire.
> > Although it seems obvious now, I hadn't realised the meaning of 10/44.
> >
> > Mal - thanks for your helpful advice and info on your antenna loading
> > arrangements. I am still trying to picture it all in my mind but it
seems
> > like the sort of relatively simple system I'm looking for - especially
> > keeping to 50 ohms. I have yet to find a supplier of the metal lined CH
pipe
> > (Srewfix B&Q??)
> >
> > [...]
> >
>