Topband: 160 Meter RFI - found another ham with nearly identical RFI

donovanf at donovanf at
Tue Jan 18 20:18:43 PST 2011

Hi Bob,

W2GPS are not hearing the same RFI source, we are hearing two RFI sources with nearly identical characteristics.  I have successfully identified the source of my RFI.  W2GPS isn't very concerned about his because he has no 16o meter capabilities.

The next task is to correct my RFI problem, thats going to be a long row to hoe...  Thankfully I have eight Beverage antennas that provide sufficient directivity that minimize but do not completely eliminate the problem in every direction except SE  The amazing thing is that my RFI source is one mile away.



---- Original message ----
>Date: Tue, 18 Jan 2011 19:56:07 -0800
>From: Robert Harmon <k6uj at>  
>Subject: Re: Topband: 160 Meter RFI - found another ham with nearly identical RFI  
>To: <donovanf at>
>Cc: topband at
>   Frank,
>   That is interesting that W2GPS is receiving the same type of
>   RFI.  You may 
>   have already done this but I would use a loop or some type of
>   directional receiving antenna to determine the bearing where
>   it is the strongest at your station and also at his station.  
>   Then plot the bearings on a map and where the line
>   intersects you may be in the proximity of the source and you
>   can narrow down from there. My most recent noise that I
>   finally tracked down here turned out to be a new "smart meter"
>   our electrical utility company  installed.  They wouldn't
>   believe me, and when I had the technician out (finally) I
>   showed him that on AM broadcast, when you got close to the
>   meter it roared.  Then, 3 months later, (nothing happens
>   quickly on this stuff, hi,hi) they replaced the meter and no
>   more noise.  Now I have a new and different noise to track.
>    It never ends. 
>   Bob
>   K6UJ
>   On Jan 18, 2011, at 6:31 PM, <donovanf at> wrote:
>     I'm not the only ham with this 160 meter RFI.  W2GPS and I
>     were discussing this today, and Rick recalled that he's seen
>     nearly identical RFI on 160 meters at his QTH 30 miles from
>     here for several years.  Like my case, its active 24 hours
>     per day.
>     Rick created a spectrum plot of the RFI at his QTH, its at
>     57.5 kHz intervals from 1600 kHz to 2000 kHz.  Just like my
>     case, the strongest RFI is in the 160 meter band.
>     I can email a spectrum plot and .wav file of the audio
>     output of an AM receiver to anyone who is interested.
>     Does anyone else hear this RFI on 160 meters?
>     It just seem too coincidental that two hams 30 miles apart
>     are hearing nearly identical 160 meter RFI, but nobody else.
>     tks
>     73
>     Frank
>     W3LPL
>     ---- Original message ----
>       Date: Sat, 15 Jan 2011 11:43:37 -0500 (EST)
>       From: <donovanf at>  
>       Subject: High Efficiency Furnace RFI?  
>       To: topband at
>       In the last few weeks a new strong variable frequency 100%
>       duty cycle RFI source suddenly appeared on 160 meters,
>       radiated from a home one mile southeast of my QTH 24 hours
>       per day.  The RFI peaks in the 160 meter band on variable
>       frequencies mainly between 1801 and 1834 kHz.  Yes, its
>       the perfect RFI storm on 160 meters!
>       Its source is a home with a recently completed major
>       addition.  At my QTH the RFI affects only 160 meters and
>       the AM broadcast band above 1600 kHz. If you place an AM
>       receiver close to the home generating the RFI, the RFI
>       extends only from 1270 kHz to 1970 kHz.
>       The RFI has amplitude peaks and valleys at 1801, 1804,
>       1818, 1823, 1827 and 1834 kHz; however, all of those RFI
>       peaks are not present at the same time. The RFI abruptly
>       switches among those frequencies a few times per minute,
>       apparently caused by some sort of variable speed
>       controller.  If you listen to the RFI with the receiver in
>       the AM mode, the RFI has a continuous AM modulation of
>       approximately 1 Hertz.
>       All of the above -- especially the one mile distance from
>       my QTH -- suggests that the source may be a new high
>       efficiency heat pump with a variable speed motor
>       controller.  
>       While I can probably use my DX Engineering NCC-1 noise
>       cancelling controller to completely null out this RFI
>       source in every direction except SE, I would prefer to
>       eliminate the RFI source entirely!   
>       Has anyone else experienced this type of RFI?  If so, have
>       you been successful in resolving it?
>       tks
>       73
>       Frank
>       W3LPL
>     _______________________________________________
>     UR RST IS ... ... ..9 QSB QSB - hw? BK

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