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Re: LF: LF E-H combiner, ideas?

To: [email protected]
Subject: Re: LF: LF E-H combiner, ideas?
From: Richard Rogers <[email protected]>
Date: Fri, 24 Aug 2012 09:04:00 +1000
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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



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