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: [email protected] <[email protected]> On Behalf Of [email protected] Sent: Montag, 29. Juni 2020 19:51 To: Elecraft Reflector <[email protected]> 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: [email protected] To: "Elecraft Reflector" <[email protected]> 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:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
