[Elecraft] K3 and phasing & noise cancelling systems

[Eric Buggee]

On 12/18/2013 3:35 PM, David Gilbert wrote:
>
> A couple of years ago I proposed that Elecraft modify the firmware in 
> the K3 to allow the phase of the local oscillator in either the main 
> receiver or the subreceiver to be adjusted in some way (possibly by 
> using a couple of front panel buttons to be used as 
> increment/decrement controls).  That would allow anyone with both 
> receivers to put the K3 into diversity mode and sum the signals from 
> two different antennas in order to null directional interference 
> (noise or QRM).  It would also allow anyone with separately fed 
> stacked antennas to play around with arrival angles.  The absolute 
> phase angles would be indeterminate and the absolute phase would vary 
> for every frequency, but nulling at every frequency would still be 
> possible.   The nulling could even be done at the audio output since 
> relative phase is preserved in the frequency conversion process, but I 
> assume that it would be more practical to do it where the the majority 
> of the DSP is already being handled ... i.e., at IF.
>
> At the time somebody at Elecraft agreed it should theoretically 
> possible and might be worth pursuing, but nothing ever came of it. In 
> any case, I've always felt that it was a nice opportunity being 
> squandered.  I think it would be a nice plus for the K3 to be able to 
> do it's own spatial discrimination.
>
> 73,
> Dave   AB7E
>
>         Hi Dave and all,
             I agree the above should be achievable I have seen such a 
scheme implemented wr to professional OTHR systems in both Tx & Rx.

             It should not be too hard on the K3 Rx side with 2 
identical Rx paths & phase coherence in bothe local oscillators.

I believe it is technically well worth pursueing.

Eric VK3AX.
>
>>
>> On 12/17/2013 5:58 PM, Gary Smith wrote:
>>> I've been having terrible RFI issues on the low bands, sometimes its
>>> up to 10M but usually its from 40M & down with 160M being the most
>>> affected. I've become aware of the MFJ and DXEngineering phasing &
>>> noise cancelling systems and how well they work to null out
>>> interference. I'm leaning toward the DXEngineering NCC-1 although the
>>> price is very high and that is holding me back from buying one right
>>> now.
>>>
>>> I have Amtrak 100' from my Inv-L transmit and HI-Z Triangular
>>> antennas and Amtrak's 25KV arcing is killing me on the low bands. I'm
>>> wondering if anyone here has a steerable antenna system similar to
>>> the HI-Z that they use for Rx with their sub receiver and... one of
>>> the MFJ or DXE phasing/noise cancelling systems.
>>>
>>> If so, how do you have your K3 set up to handle the different systems
>>> and how do you connect your noise cancelling unit so as to still
>>> steer your Rx antenna?
>>>
>>> Thanks
>>>
>>> Gary
>>> KA1J
>
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