[Elecraft] K1 K2 - Interesting noise

[Ron D'Eau Claire]

Yes - back in the 1960's stereos, pa systems such as those found in churches
and businesses and even some TVs and telephones all over a wide area
covering several towns heard a loud 400 Hz buzz that lasted several seconds
at a time and which repeated perhaps twice a minute. It went on 24x7. 

I was called upon to help quiet some systems and, as a Ham operator, had to
"prove" my radio wasn't the cause in a few cases. That was easy. I just had
the neighbors turn up the volume so he could hear the buzz outside and then
pointed to the antenna revolving on top of distant Mt Umunhum so they could
hear the noise erupt every time the antenna pointed their way. (Umunhum is
an American Indian word meaning "resting place of the hummingbird". Somehow
that was appropriate.)

The interference was very strong at my QTH at least 20 miles line-of-sight
from the antenna.

The peak pulse power from such systems is often huge and is always a
possibility when strange things happen in a new location. 

There was general relief all over the area when the huge antenna disappeared
from the mountain. Little did I, or anyone, realize at that time that we
were about to be invaded by millions of noise switching "wall warts" and
other digital noise generators. Quieting Umunhum's noise was child's play
compared to dealing with them. 

Ron AC7AC  

-----Original Message-----
 That was a problem with the air defense radar at Almaden Air
 Force Station (Mt. Umunhum, south of San Francisco) being
 rectified in all the home stereo systems in what is now called
 "Silicon Valley" until that radar was replaced by PavePaws at
 Beale AFB.

--  73 de K2ASP - Phil Kane
    Elecraft K2/100   s/n 5402