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Date: Sat, 25 Aug 2012 04:46:33 +0200
From: =?ISO-8859-15?Q?Stefan_Sch=E4fer?= <Stefan.Schaefer@iup.uni-heidelberg.de>
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Subject: Re: LF: LF E-H combiner, ideas?
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Hello Richard,

Thank you for the input. It is certainly a circuit/image that will find=20
its place in my LF folder!

About the broadened noise pulses: Martin's loop has 8m^2 and produces a=20
bg signal for the RX. So the BW is quite wide, probably > 3 kHz. So i=20
don't expect this problem here. Her has no possibility to buy all the=20
parts of the circuit so we will go on with the more easy config.

Thanks and 73!

Stefan/DK7FC

PS: Can you still receive on LF? If so, we could try if you like! VK7ZL=20
copied traces of my signal in March this year...



Am 24.08.2012 01:04, schrieb Richard Rogers:
> G'day,
>
> When I used to listen to the ZLs on 180KHz (15 years ago!), I used an=20
> active vertical and a loop combined in this circuit=20
> https://dl.dropbox.com/u/100084148/Phasing%20antennas.tif
> The circuit was published by the late Andrew Corney, ZL2BBJ, in=20
> Break-In in 1996.   It certainly allowed me to null out signals, but I=20
> found that it did not help greatly in the reduction of noise as I was=20
> listening mostly just after sunset when the signals and noise were=20
> both coming from the East.
> One problem I found when using a tuned loop was that the selectivity=20
> of the loop broadened the noise pulses and stopped the noise blanker=20
> in my TS-920 working well.
>
>
> On 8/24/2012 7:43 AM, Stefan Sch=E4fer wrote:
>> LF,
>>
>> Currently i'm working on a E-H combiner together with Martin/YV7MAE=20
>> in Venezuela.
>>
>> He has a well working E field antenna, about 80m wire, some m up,=20
>> resonated with a ferrite rod and a variable transformer and some=20
>> output turns on a separate winding and a separate LF earth system.=20
>> 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=20
>> DCF-39 in 8000 km without problems in a 300 Hz CW filter. With this=20
>> loop he can receive my DFCW-90, so far the best S/N was 15 dB in 22=20
>> mHz. The loop is very directional. Turning the loop by +-15 deg shows=20
>> a clear decrease of the DCF S/N.
>>
>> Now we're planning to combine the two signal sources to obtain a=20
>> cardioidal pattern like the K9AY and similar provides (used by W1VD,=20
>> F1AFJ and others). The signal levels of both, the E and H antenna are=20
>> producing roughly the same signal levels on the RX (difference < 5=20
>> dB). This is the circuit that we want to try tonite:=20
>> https://dl.dropbox.com/u/19882028/LF/DSC04412.JPG
>>
>> The H component is fixed and then it is possible to "add" a certain E=20
>> level, hopefully resulting in some noise reduction of QRN coming from=20
>> the backside (SW). Later, the F/B may be optimised by adding some C=20
>> 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=20
>> there a better way to start?
>>
>> Note that just one ferrite core is available, i.e. no high end, low=20
>> noise op amps and so on.
>>
>> 73, Stefan/DK7FC
>