Message-ID: <4E341070.60400@iup.uni-heidelberg.de>
Date: Sat, 30 Jul 2011 16:08:48 +0200
From: =?ISO-8859-15?Q?Stefan_Sch=E4fer?= <schaefer@iup.uni-heidelberg.de>
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To: rsgb_lf_group@blacksheep.org
Subject: LF: K9AY loop for LF at W1VD
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LF,

I just searched for a LF /p antenna that can be fixed in the trees of a 
nearby forest. I quickly came to the pages of W1VD and saw his design of 
a K9AY loop ( http://www.w1vd.com/k9ay11.pdf).

Jay, if you are still QRV here (long time ago), how well does design 
perform, i.e. how many dBs can a noise source be attenuated by adjusting 
the potentiometer (that changes the dynamic "resistor", i.e. the output 
of the optocoupler? What angle is covered by this method?
It is an interesting idea to do it this way!

Can you give us a short report about the performance of your antenna?

I would like to arrange a fixed loop for LF receiving in the forest to 
be QRV on LF without the need to carry my rather big and heavy RX loop 
antenna in the car. So i could use my bike instead.

BTW, my /p LF homemade receiver using the SBL3 has only one amp stage 
and the total power needed is 12V*12 mA! So i got the idea to try a 
DC/DC converter to supply the RX out of the USB! This would make a heavy 
battery obsolete. I took a 4.5 Euro 1W unregulated converter and added a 
78L12 and 2* 100 nF. As far as i can see the converter (=SMPS) adds to 
moving or broadband noise to the signal received! Good news for sceptics 
about SMPS ;-)

If all works well i just need the netbook and the RX which is in the 
format of 10cm x 3cm x 8cm and a /p 70cm radio to become QRV soon :-)

73, Stefan/DK7FC