On 12 Mar 2014 at 11:11, Roger D Johnson wrote:
> Sure wish I knew the secret to get the FCC to do anything.
> 73, Roger
Yes. Wouldn't that be nice?
I have been plagued by a very serious noise level here for the past couple of
months, at least.
20db over S-9 on 80 meters, 10 over 9 on 40, S-9 on 20, haven't checked
much higher. Once in a while, it will suddenly go away, then will resume
shortly thereafter. It is on 24/7.
On 80 it sounds like a radial aircraft engine running at a steady speed when I
switch the FT-890 to AM.
I have elminated one possible source: my own home. I connected the
FT-890 to a battery, then switched off the house main breaker. Result: no
I then dug out my small Radio Shack AM/FM/SW receiver, and after opening
it up to determine 1) IF it had a loopstick antenna (it does) and 2) its
orientation, I then marked the case with a double-ended arrow and tried to
use it to pinpoint a source by tuning to the high end of the BC band where
there are no local stations and looking around. Unfortunately, there is no
attenuator on this radio, and the noise is so strong it simply overwhelmed the
Next, I asked the noise expert with our local power provider, Avista, to come
down from Coeur d'Alene, Idaho, about 80 miles north of me, to bring his
fancy hand-held parabolic job to see if the noise was power-line related.
After wandering around over quite a number of blocks, the only source he
thought MIGHT be the problem was coming from our next door neighbor's
new Ruud furnace.
I called the folks who installed that, a local plumbing company and they sent
out a fellow whom I know by name. While we communicated by cell phone,
he first unplugged the furnace, then switched off all power to the home.
The furnace, by the way, does NOT have a variable speed motor on or in it.
Result: no difference whatever.
Next, I dug out of my "junque box" one of several Stoddart NM-10 loop
antennas, a shielded loop which is 3 feet in diameter, deciding that I would
build a twin-ax to coax opamp (OP-27) based interface, couple that to the
FT-890, and go looking.
Turns out that the natural resonance point for this particular loop is 500 KHz,
which isn't really going to help me much. Its inductance is 500 uH and that is
internally paralleled with an approximately 200 pfd capacitor.
Even if I were to remove that capacitor, and use an external capacitor to tune
the loop, the inductance is so great that it would be difficult to use the loop
any frequency much above the 160 meter band.
I do have a 6" diameter Stoddart loop which is part of the NM-10 system
(which is also the military AN/URM-6(*) of which I have several examples).
Although I have not yet checked its natural resonance point, I am almost
positive it will also be 500 KHz.
So, I am now to the point where I am either going to have to refurbish and
get into operation one of my Stoddart NM-20As (150 KHz through 25 MHz)
or build a loop which I can attach to the FT-890.
If I build one, at this point I am unsure of how large to make it, and whether
or not it would be necessary to build a shielded one. I suspect I will need at
least two loops, one large (3 feet diameter or so) one, and one much smaller.
I also feel that the loops should be shielded, but will defer to those here who
know more than I do.
Once this is done, I can then proceed to drive around in an attempt to
triangulate this crap. I have printed off a detailed map of the city, and areas
around it, and can get true directions easily enough.
I really wish I still had the DAG-1 I had when I was much younger.
I will gladly accept any suggestions from the folks here.
Most of my operating is HF traffic handling and NTS duties, mostly via CW,
some PACTOR, and some SSB. This situation is causing major problems.
Ken Gordon W7EKB
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