[RFI] battery-charger RFI ?

Patrick Dyer pjdyer at swbell.net
Sun Dec 25 09:26:04 PST 2011


I know how some/many frown upon using audio samples of RFI as aid to
determining a probable source, but this is from 10-MHz, wide AM, FT-847
(it can be heard faintly up to 50-MHz)  A recently-obtained ANC-4 has
had varied success, depending on the band.

http://www.qsl.net/wa5iyx/ra/nx-20111225-15--z.wav

peak pulse is 10-20+ over s-9 (on perhaps, at lowest, an s-7 background)
It resembles some samples found on the Web of battery-charger RFI.
I've heard many an electric fence but this seems "different" as ...

This RFI has what I would call a "digital component" to it with tuneable
peaks (that vary in time/freq/intensity) - I lack anything that would
give a good spectrum-analyzer profile of those periodicities.  This
pulsing is just one of several "signatures" that this RFI has (unless
I'm somehow dealing with overlapping multi sources here).  It seems to
favor the weekends (first noted two weeks ago).  Much of the time it's
just a raucous "buzz" that on some freq peaks the FT-847 NB is rather
effective.  Oddly, it doesn't seem to affect the mw bc band at my QTH.

  Last Sunday a non-pulsing mode of this was detectable on 2m and so
RDFed with an IC-A4 (at 136 MHz) and 4-el 2-m Yagi (part of an old 11-el
Cushcraft).  That was localized to two possible residences c. 300' n.e.
of me in a cul-de-sac (which due to winding streets is a 1-mile one-way
trip!)  Before I could pinpoint it the RG-58's PL-259 and/or BNC adapter
failed on the system :<  I explained what I was doing (and living on the
street just behind them since 1972 - a decade or more before those
places were built).  Resident cooperation was varied, but later having
to re-explain this all to two SAPD officers that one resident (with whom
I'd left my name and address) had called doesn't seem a very good omen.

Revisiting the area to pinpoint it with a now-fixed 2-m RDF antenna is
further complicated in that it isn't always detectable on 2m and my
being semi-invalid mobility wise in recent years.

73, Pat - WA5IYX
San Antonio, TX


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