[RFI] Don't ask, "What is it?" Instead, ask, "Where is it?"

[Frank N. Haas KB4T]

Trying to identify what a certain sounding interference might be may
be entertaining but it's a waste of time. Perhaps some joy comes from
guessing what a sound might be and then finding the source and being
right. To me the more important question is, "Where is it coming
from?"

If I'm experiencing interference on a particular frequency, the first
thing I want to do is to determine from what direction the
interference signal is coming. I don't care what it MIGHT be. I know
I'll find out what it is when I actually find it.

If the interfering signal can only be heard on HF frequencies, then I
want to equip myself with something that will allow me to
direction-find (DF) such a signal. It doesn't matter to me if it's
humming, buzzing, spitting, burping or wheezing. If I can hear it, I
should be able to track it.

If I can hear the interference on higher frequencies, then I can use a
smaller antenna. Thus I want to know the highest frequency at which I
can hear the interference. If I'm really lucky, I'll be able to hear
it at VHF. I'm only lucky on occasion.

Real power line noise has a 120 Hz characteristic thanks to the arcing
occurring on both peaks of the sine wave. A nice fact but useless in
locating the source. I'm much more interested in finding the best way
to get a bearing and get closer.

Nearly every week, a note pops up on this reflector asking for an
opinion or confirmation on what some sound might be. I never answer
these notes because I view such an exercise as pointless. Rather than
guess about what it might be, I'd rather DF it and know for sure.

I admit that in my line of work, time is money. Find 'em fast and get
'em fixed. Most of the sources I pursue are real power line
interference but sometimes I find a consumer electronic device.
Variety is the spice of life. One thing is certain: I waste no time
speculating about what it might be. I just find it so I can know for
sure.

73,

Frank N. Haas KB4T
Utility Interference Investigator
Florida