[TenTec] Power Line QRN?

[rohre]

Shawn,
Turn on a flourescent desk light and hold an AM radio up against it.  That is
one form of power line noise.  Another is a rough 60 Hz tone mixed with 180
Hz.

Near most any AC cord, again with the radio, you will hear that.  The more
current in the AC cord, the more noise picked up by the radio.

>From noisey power lines, you will get a frying sound, which could be HV corona
discharge. You may get snaps and pops from arcovers to green plants growing
into the 230VAC or higher lines.  You can get intermittent sounds when loose
hardware on a pole vibrates in a wind gust.

In short anything that is background in an urban environment may ultimately be
linked to the power lines in some way.  But, there are local sources like door
bell transformers, touch lamps or other SCR/Triac control, (speed or motor
controls, dimmers, etc.)  Your computer CRT will give interesting results if
you hald the radio, AM or SW up to the screen!  The CPU has discrete steps of
noise that are clocks and their harmonics of the controlling crystal
oscillator.

On the air, in your receiver, you will find more power line caused noise in
the AM an MW range.  But, there are also peaks at 200 MHz, thus an AM aircraft
receiver could be used with a Yagi to listen to power lines.

Propagation noises, on a band like 40M with current solar situation, or on 20M
at late night when it closes, may sound like a growling sound, that only
covers part of a band.  Other natural noise includes FM slides, (whistlers)
usually heard at VLF, and static of thunderstorms nearby or in the direction
your antenna favors, but far away.

One way to learn what is power line and what is ionospherics, is to take an
all band SW radio far out in the country away from power lines and see what
the bands sound like over several hours, both day and evening.  By listening a
lot, you learn to recognize various types of noise.

GL and 73, Stuart K5KVH

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