Topband: QRN help

[Barry Gross]

I've been regularly experiencing "waves" of qrn in the NE direction during
evening hours.  Typically, I have quiet for 20-60seconds between periods of
+3-6dB qrn lasting a similar length of time.  The qrn periods typically
build up gradually.  The noise is only heard in the NE direction and I
typically hear it 2-5 hours after sunset.  I'd appreciate any comments on
whether this is a natural or man-made phenomenon.

If you're interested, there's a soundclip (rx w NE Beverage) of several
minutes duration at http://n1eu.com/qrn_record.mp3

Thanks for any comments & 73,
Barry N1EU