[Elecraft] Diversity receive versus QRM eliminators

[gt-i at gmx.net]

Andy,
mni tnx - good ideas! Will rewire my QRM box to the K3 RXIn out to avoid 
the extra PTT-relay clicks imposed by the QRM-box. It is the Wimo-QRM 
Eliminator. Not as Hi -end as the NCC-1 but a start.
Just looked-up the DXE  - now the NCC-2 is out and it now also has the 
same extra PTT switching as my cheap box! Why is this required, as I 
just learned the K3 can handle this smoothly?

tnx 73 Gernot DF5RF


Am 29.06.2020 um 22:51 schrieb hb9cvq at hispeed.ch:
> Hi All,
>
> I use in my K3S the RX in and RX out (RCA plugs) on the backside for
> inserting the denoised signal  from my DXE NCC-1 Phasing Box output plug.
> This box has two channels, were one can do e.g. up to -180deg phase
> reversal. CH A and B signals are finally send to an internal power combiner
> and to K3S RX in.
>
> My have 2 selectable TX/RX antennas, 2x36m tuned doublet 160 to 6m @ 24m
> center and a Steppir DB18E @ 18m.
> RX signal come out safely from K3S RX (out) going to CH A NCC-1.
> My QRM local noise pick-up ant is a 1m diameter ALA 1530 electronic mag.
> loop (predominantly picking up local noise, no DX , horizontally mounted in
> the attics, about -60dB decoupled from TX antennas)
> This signal goes into CH B of NCC-1
> By carefully equalizing/adjusting the amplitudes CH1 /CH2 NCC-1 I then try
> do "Anti Phase". This will mostly reduce the local noise on the used main
> antenna.
>
> The limitation is you can only effectively  focus (phase) on one single
> local QRM source. The unit NCC-1 is good up to around 17m Band. It is hard
> to get more than 20dB S/N (about 2.5 S-Units) improvement.
>
> In some local noise cases, not being a point source (Line source : PLC ,
> VDSL etc. ) I am more successful using a LISN ( EMC , Line/Mains 50 Ohm
> stabilization, decoupling network, 230V, 50 Hz) to safely replace the signal
> from the mag. loop.
> This procedure picks up the conducted noise on the mains in the house/flat
> more in an integral way. This does not act as a "point source"
>
> Experiments with predominantly E-field ( small/short dipole antennas) for
> local noise pick up are ongoing.
>
> 73  Andy
> HB9CVQ, DK2VQ, AK4IG
> https://www.qrz.com/db/HB9CVQ
>
>
> -----Original Message-----
> From: elecraft-bounces at mailman.qth.net <elecraft-bounces at mailman.qth.net> On
> Behalf Of donovanf at starpower.net
> Sent: Montag, 29. Juni 2020 19:51
> To: Elecraft Reflector <elecraft at mailman.qth.net>
> Subject: Re: [Elecraft] Diversity receive versus QRM eliminators
>
> Diversity is not helpful as a QRM eliminator.
>
>
> Antennas with steerable nulls can be helpful, small loop antennas have very
> deep nulls but also require a high gain, low noise figure preamp and very
> careful attention to common mode rejection during installation
>
>
> 73
> Frank
> W3LPL
>
> ----- Original Message -----
>
> From: gt-i at gmx.net
> To: "Elecraft Reflector" <elecraft at mailman.qth.net>
> Sent: Monday, June 29, 2020 5:18:30 PM
> Subject: [Elecraft] Diversity receive versus QRM eliminators
>
> Hello all,
> In a recent rush to eliminate urban noise I bought an QRM eliminator.
> The working principle is to null out signals by shifting the phases of two
> antennas (one main/tx and one rx). I can see the effect sometimes, but it is
> not the holy grail for all types of QRM. I still don't get rid of the
> PSU/LED/plasmaish noise here, sometimes the S/N is a bit better but maybe
> thats my inner impression to justify buying this thing.
> Now, I do wonder how this differs from diversity receive, effectively versus
> local QRM.
> Note I have a 10m vertical as the 2nd ant, while the main ant is horizontal.
>
> Any thoughts or hints ?
> tnx 73 Gernot DF5RF
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
>
> This list hosted by: http://www.qsl.net Please help support this email list:
> http://www.qsl.net/donate.html Message delivered to donovanf at starpower.net
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html Message
> delivered to hb9cvq at hispeed.ch
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to gt-i at gmx.net