[Elecraft] K3 and phasing & noise cancelling systems

[David Gilbert]

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



>
> 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