Message-ID: <5036B6E0.3020205@netspace.net.au>
Date: Fri, 24 Aug 2012 09:04:00 +1000
From: Richard Rogers <vk7ro@netspace.net.au>
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To: rsgb_lf_group@blacksheep.org
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Subject: Re: LF: LF E-H combiner, ideas?
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G'day,

When I used to listen to the ZLs on 180KHz (15 years ago!), I used an 
active vertical and a loop combined in this circuit 
https://dl.dropbox.com/u/100084148/Phasing%20antennas.tif
The circuit was published by the late Andrew Corney, ZL2BBJ, in Break-In 
in 1996.   It certainly allowed me to null out signals, but I found that 
it did not help greatly in the reduction of noise as I was listening 
mostly just after sunset when the signals and noise were both coming 
from the East.
One problem I found when using a tuned loop was that the selectivity of 
the loop broadened the noise pulses and stopped the noise blanker in my 
TS-920 working well.


On 8/24/2012 7:43 AM, Stefan Schäfer wrote:
> 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
>
>
>
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-- 
73, Ric, VK7RO