[CQ-Contest] SO2R filtering help

[Edward Sawyer]

Dan, I am happy to help you.  If you are running Low Power, then all is very doable.  First of all you need to separate "harmonics" from adjacent broader band interference that is raising the noise floor of the other radio receiver.

I use Dunestar - 6 band filterbanks - and dual FT1000MPs.  Running 200W, I hear a very slight noise floor rise while transmitting (maybe 3 - 5db vs the S=0 noise floor - ie less than S1 on the meter).  This for a monoband beam 10 feet above another.  However as I get near a harmonic of my transmit frequency, it might be S9 on the meter at that harmonic and have 5khz of presence on SSB and less than a khz on CW.

Can you describe in the above terms what you are hearing?

Ed  N1UR

-----Original Message-----
From: CQ-Contest [mailto:cq-contest-bounces at contesting.com] On Behalf Of Dan
Sent: Tuesday, July 23, 2019 5:07 PM
To: cq-contest at contesting.com
Subject: [CQ-Contest] SO2R filtering help

I am baffled by a problem that I’m having setting up to do interference free SO2R operating running LP. I’ve tried stubs and they have no effect on harmonics. I have good W3NQN style bandpass filters and THEY don’t seem to knock down harmonics. I know the stubs/filters are working as they greatly attenuate received signals if I put them on the band of harmonic attenuation. (40 meter filter in line while receiving on on 20 ) I’m using a K3 an FT1000MP. Filtering and stubs have no effect on either radio.

I have read that there could be something other than the rigs creating harmonics. IE  corrosion, wall warts, grounding problems. What I need are ideas on how to track these buggers if indeed this is the problem.
Thanks in advance 

Dan W8CAR
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