Message-ID: <5036A3FA.5000508@iup.uni-heidelberg.de>
Date: Thu, 23 Aug 2012 23:43:22 +0200
From: =?ISO-8859-15?Q?Stefan_Sch=E4fer?= <Stefan.Schaefer@iup.uni-heidelberg.de>
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To: rsgb_lf_group@blacksheep.org
Subject: LF: LF E-H combiner, ideas?
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LF,

Currently i'm working on a E-H combiner together with Martin/YV7MAE in 
Venezuela.

He has a well working E field antenna, about 80m wire, some m up, 
resonated with a ferrite rod and a variable transformer and some output 
turns on a separate winding and a separate LF earth system. The 
bandwidth is wide and the signal levela are high.
He also has a loop which is resonated to 137 khz. He can see and hear 
DCF-39 in 8000 km without problems in a 300 Hz CW filter. With this loop 
he can receive my DFCW-90, so far the best S/N was 15 dB in 22 mHz. The 
loop is very directional. Turning the loop by +-15 deg shows a clear 
decrease of the DCF S/N.

Now we're planning to combine the two signal sources to obtain a 
cardioidal pattern like the K9AY and similar provides (used by W1VD, 
F1AFJ and others). The signal levels of both, the E and H antenna are 
producing roughly the same signal levels on the RX (difference < 5 dB). 
This is the circuit that we want to try tonite: 
https://dl.dropbox.com/u/19882028/LF/DSC04412.JPG

The H component is fixed and then it is possible to "add" a certain E 
level, hopefully resulting in some noise reduction of QRN coming from 
the backside (SW). Later, the F/B may be optimised by adding some C on 
the loop to change the resonance and so the phase between E and H.

Does someone have additional advice or tried a similar project? Is there 
a better way to start?

Note that just one ferrite core is available, i.e. no high end, low 
noise op amps and so on.

73, Stefan/DK7FC