[RFI] RFI Frustration

[Jim Idelson]

Thanks for the tips.

I have to say that over the past 5-6 years I've gotten pretty good at tracking 
down any kind of powerline arcing noise using the techniques you describe. I've 
got the directional antennas at home, then the HF and VHF gear in the car, and 
then the handheld AM radio with a handheld yagi for getting really close. In 
fact, the real reason I'm so frustrated right now is because after two months 
of tracking and working with the power company, all the hardware on a pole that 
was both in the suspect direction and exhibiting some clear arcing symptoms was 
replaced last Saturday. I was very optimistic that this would be the solution. 
But, it was not. Although that pole went completely quiet, the noise I hear at 
my station remains.

Now, regarding the 78.5kHz, I am definitely interested in this signal, but I 
don't want to be totally focused on it because I can't establish a clear 
connection between that noise and what I hear up on 20m and above. By the time 
we are at 20m, the noise sounds quite different, and it has a broadband feel to 
it. Not discrete 78.5 kHz multiples like the first few harmonics at VLF.

I took my Kenwood TH-F6A out for a walk today with the ferrite loop antenna 
activated.  That radio didn't hear much with the internal antenna. I can't tell 
if I'm getting close to anything with that setup. There's got to be a better 
way.

Jim

> Hmmm ...

> also very loud at 78.5kHz and at all multiples of 78.5kHz right
> up into the AM broadcast band.

We can work with this.

Any ham who is tying to track down 'noise' should have
at his disposal a battery-operated AM  radio for the utility
of its highly directional ferrite 'loopstick' antenna.

While not a panacea, and you might have to 'watch out'
for coupling to fields as opposed to a 'propagated' signal
at AM broadcast frequencies, but stronger in these cases
still means 'closer to the source'.

I have hiked around in the past checking 'pole' noise by
holding the AM receiver in vicinity of the ground wire
running down the pole, but I digress ... if this signal is
receivable on the AM broadcast band I suggest a little
recon using the AM receiver in the car!

I have also had success using a consumer-class
transistorized portable battery-op AM/SW receiver
that utilized a ferrite rod antenna up through 6 MHz; this
has worked well DFing 80 Meter noise sources, one of
which was 3/4 mile or so distant (a power pole power-
factor correction cap bank complete with timer-controlled
switch on a 3-phase 14 KV line)!. Another ham had gone
out using a 2M rig and a beam and never found it; I
noticed that the amount of energy from this source was
considerably less in the 100 MHz and up bands
compared to that in the SW spectrum.

And FWIW - my hall light, w/an incandescent wired up
to a remote control BSR X10 light dimmer module is
only noisy with the light on and is quiet with the light off.

Jim P  // WB5WPA //


----- Original Message -----
From: "Jim Idelson" <k1ir at designet.com>
To: "RFI Reflector" <rfi at contesting.com>
Cc: "CQ-Contest Post" <cq-contest at contesting.com>
Sent: Thursday, February 14, 2008 5:13 PM
Subject: [RFI] RFI Frustration


> Well, it's the night before the contest and the noise is still there.
>
> It's a 24/7 noise and I can DF it in one direction with yagis on 40-10
meters. It's pretty broadband and it has a sputtering sound, somewhat like
this light dimmer noise -
http://www.arrl.org/tis/info/HTML/rfi-noise/noise/noise-files/lightdimmer.mp
3
>
> found at
> http://www.arrl.org/tis/info/HTML/rfi-noise/appliances.html
>
> Is a noisy light dimmer going to be a constant source or does it change
with load and when turned off?
> I had been listening for this at high frequencies, but when I saw that
this is something that has a baseband frequency in the 150kHZ range, I tuned
my big rig in the station down there on a 160m dipole, and there is a very
loud noise at 157kHz. It is also very loud at 78.5kHz and at all multiples
of 78.5kHz right up into the AM broadcast band.
>
>
> Suggestions for better DF'ing techniques? I've been outside around the
neighborhood with my HT, sniffing power meters, wires coming down he power
poles, etc. There are some hot spots, but nothing like a smoking gun.
>
> I have a little time tomorrow to sniff around the neighborhood some more
to see what I can find. I've been in the two closest house with the HT, but
found nothing.
>
> Wouldn't it be cool to find and eliminate this just in tme for the
contest?
>
> 73,
>
> Jim Idelson K1IR
> email    k1ir at designet.com
> web    http://www.k1ir.com
>


<



Jim Idelson K1IR
email    k1ir at designet.com
web    http://www.k1ir.com