Topband: Mysterious noise - part 2
tod at k0to.us
Thu Nov 9 18:06:03 EST 2006
I am using this as the most efficient way to communicate with the many folks
who sent me ideas about sources and search methodology for my 'unique' 160
1. Taking the suggestions of a number of people I outfitted my ICOM-706 with
a gel cell power source [16 pounds] and a 5 turn hand-held loop. I tested
this in my house and found the ICOM could easily pick up the noise signals.
I carted the 'portable' assembly out to the K9AY loop and started to look
for the signal. No noise signal. I walked back to the house checking on the
way. About 15 feet from the house the signals appeared. Walking around the
house I found that all loop headings pointed to the house as the culprit.
2. I found a place where the signal was strong and deposited my portable
receiver listening to the beat tone at a high audio level. I disconnected
the Cable One cable drop going into the house and found no change. I went to
the inside breaker panel and turned all breakers OFF. AHA, no noise signals.
I turned the breakers on one by one. The noise reappeared only when the
breaker to the pump, which supplies water for my home, was activated.
3. I went off to the well pit with the 'portable' receiver and used the loop
to reach down into the pit and look for the source of the signal. No
signal. I went back to the house. I checked the power mains coming into the
house. The loop said that the source was behind what appeared to be a sealed
panel of the power entry box. I have called the power company and they
assured me "help is on the way" and should arrive by early next week.
4. Meanwhile, I have found a "work around" using a BOF and an MFJ-1026. [BOF
= beverage on floor]. I found that if I use about 30 feet of wire on the
floor of the shack I get noise pulses on the wire about at the same peak
level as the ones coming in from the K9AY. I checked the two signal source
on my spectrum analyzer and the pulses and periods were identical. Next I
used the wire [the very short beverage on the floor] to provide a sense
antenna input for the MFJ-1026 and then used the K9AY as the feed into the
main antenna input. A bit of adjustment of amplitudes and the phasing
between the signals and suddenly the CW beat from the noise pulse on the
receiver vanished [still there but way, way down]. On the air tests
indicated that I need to retune very, very slightly every 75 kHz to get the
CW beat to vanish.
5. The issue still remains -- what device is capable of generating such
regularly spaced pulses with essentially identical magnitude over hundreds
of kHz of spectrum and has a 1 sec break in the pulse stream every 90
Suggestions gratefully accepted.
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