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K3 and phasing & noise cancelling systems

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Gary Smith-2

K3 and phasing & noise cancelling systems

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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Jim Wiley

Re: K3 and phasing & noise cancelling systems

I have a NCC-1, and it works well. My antennas are a vertical-firing
cubical quad for 75 meters (NVIS antenna) and a low 80-meter dipole
(noise sense antenna). I do not have a steerable array. Keep in mind
that the noise cancelling unit will null out noise from ONE direction
only. If you have multiple noise sources with signals coming in from
different directions, you may be disappointed. It does a bang-up job on
the neighbor's plasma-screen TV.

- Jim, KL7CC

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
>
> ---
> This email is free from viruses and malware because avast! Antivirus protection is active.
> http://www.avast.com
>
> ______________________________________________________________
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>
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> Please help support this email list: http://www.qsl.net/donate.html
>

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David Gilbert

Re: K3 and phasing & noise cancelling systems

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

Eric Buggee; VK3AX

Re: K3 and phasing & noise cancelling systems

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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Igor Sokolov-2

Re: K3 and phasing & noise cancelling systems

In reply to this post by Gary Smith-2

I have Inv L connected to RX1 of my K3 and Hi-Z triangle connected to Aux RX
but no canceling system. I have to do this canceling in my head and it works
to the extend. I think, if you connect Hi-Z to one of the inputs of noise
canceling device and some noise antenna (TX antenna for example) to another
input, you will be able to do what you want. But then, switching the
direction of HI-Z will require readjustment of canceling device every time
you do that.

73, Igor UA9CDC

----- Original Message -----
From: "Gary Smith" <[hidden email]>
To: <[hidden email]>
Sent: Wednesday, December 18, 2013 8:58 AM
Subject: [Elecraft] K3 and phasing & noise cancelling systems

> 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
>
> ---
> This email is free from viruses and malware because avast! Antivirus
> protection is active.
> http://www.avast.com
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
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> Please help support this email list: http://www.qsl.net/donate.html

Gary Smith-2

Re: K3 and phasing & noise cancelling systems

In reply to this post by Gary Smith-2

Thank to all for the replies!

After talking with the tech at DXE it appears the problems involved
in removing my QRM with something like the NCC-1 are iffy at best.
After numerous failed attempts at using different Rx antennas, my
best chance to reduce the noise to better levels appears to give the
NCC-1 a try.

The price of a new one for an experiment that may well not work is
more than I can afford. So if anyone has a NCC-1 they are not finding
useful, please contact me directly, a good used one is at least worth
trying out; if it works, it would be a Godsend.

It would be awesome if Elecraft encompassed this in a K3 update but
I'm not holding my breath on this one.

Thanks & 73,

Gary
KA1J

> 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
>
> ---
> This email is free from viruses and malware because avast! Antivirus
> protection is active.
> http://www.avast.com
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list:
> http://www.qsl.net/donate.html
>

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