I used to have a radio repair shop back in Inglewood, CA.
Right under the approach path to Los Angeles International
Airport.

One of the more annoying things was a repetitive noise
approximately every 20 KHz from the broadcast band up
through 30 MHz.

I moved to Ranger TX, pretty much in the middle of nowhere.
The noise followed me.

So, today while listening around on an unrestored Collins
51J3 I got annoyed listening to this and got to thinking.
"What is common with Inglewood and Ranger?"

The closed circuit TV security system.
Turn off the DVR and camera supplies.
No, that wasn't it.

Turn off the local area network router and switch.
No, that wasn't it.

Unplug the Panasonic Hybred phone PBX.
Bingo!

For the first time in 5 years I haven't had to listen
to this noise across the entire HF spectrum.

Something is nasty inside the PBX. I have had others
that did NOT put out all that kind of hash.

Something new to play with in my spare time I guess.

Jeff-1.0
wa6fwi

--
"Everything from Crackers to Coffins"

The plot thickens, this afternoon, I turned it back on.
The noise is back. Ok, start unplugging things from the
in and out ports.

Looks like extension 24 and 25 are the culprits. Those
two go via a Cat-6 cable to two phone jacks at the work
bench.

I'll see about finding some ferrite to see if I can tone it
down a bit.

Jeff-1.0
wa6fwi


--
"Everything from Crackers to Coffins"