[50mhz] 50 MHz Communications Birdie?

[Lance Collister]

Hello, 

We would sure appreciate some guidance from anyone who might have some experience
with the type of interference we are getting here on 6m.  I was talking to Barrie
tonite on 6m, and he happened to mention that he had noticed a rough sounding, VERY
LOUD, and WIDE, intermittent "birdie" (for lack of a better word) that drifted
around the 6m band between 50.150 and 50.200.  I was shocked! I had noticed a signal
like that for the last couple of years from MY QTH!  But I had always thought that
it was just a local computer birdie in the neighborhood or something.  I was very
surprised to learn that we were in fact both hearing the same signal (we are 21
miles apart)!  And John (30 miles south of the Missoula Valley) confirmed that the
signal in question appeared to be located somewhere in between us.

So, I started investigating it a bit further.  In the FM mode, it sounds like a very
loud buzz.  While looking at in Spectran, it appears to have a lot of 60 Hz
harmonics.  Here is what it looks like:

http://www.bigskyspaces.com/w7gj/W7GJbirdie.jpg

Usually, it just sits there wobbling around in frequency, but from time to time (if
I listen in the FM mode), I can hear a decending series of 4 or 5 tones, like an
encoder of some sort).  Sometimes after such a tone burst, the signal goes off the
air for a brief time.  Other times, I then can weakly hear voices come on, but I
can't make them out.  The signal can be anywhere between 50.125 and 50.200, but
usually has been up around 50.180.  Tonight, it was between 50.150 and 50.165. 
Since it appears to be an NBFM signal, it takes out about 10 KHz of the band
wherever it moves.  The signal strength seems to vary, but is usually S9 here at my
place (and much stronger at Barries QTH).  Still, when most of the DX stations you
work are less than S1, such a marauding signal is totally intolerable!

Could it be intermod from some some sort of pager?  Or a local oscillator for some
much higher frequency communications link?  If anybody has any ideas, we would sure
appreciate hearing from you so we can try to figure out where it is coming from and
try to get it contained!  

MNI TNX!  73, Lance
-- 
Lance Collister, W7GJ (ex: WN3GPL, WA3GPL, WA1JXN, WA1JXN/C6A, ZF2OC/ZF8)
P.O. Box 73
Frenchtown, MT  59834  USA
QTH: DN27UB
TEL: (406) 626-5728   FAX:(406) 728-6320
URL: http://www.bigskyspaces.com/w7gj