[RFI] RFI Digest, Vol 69, Issue 10

G. White radiotrade at rogers.com
Tue Sep 16 13:00:28 EDT 2008

Ron...I sure feel for you and know your frustration! I am putting up with 
RFI so bad that, sadly,  it may be time to pack it in.

Probably the first thing it to be sure is its not from within your home.( 
which you have done)  I've embarassed myself a few times, cursing a 
neighbour under my breath, only to find it was my wx station, or my tower 
mounted video camera etc...But, it the the INTERMITTANCY and DIFFFERNT TYPES 
of interferrnece that is tough to solve!

Be carful - it can certainly be power line noise and/or induced/transmitted 
from a power customer and/or and unintetional radiator such as switching PS 
or TV or digital eqipment etc, etc...I find that you MUST find a way to 
identify how many diferernt sources there are, before you can find it. If it 
ALL starts and stops at once, as you discribe, then it could be only ONE 
source. As long as its the same source that is starting and stopping each 
time, and not 2 alternating etc!

I have been fooled many times by powerline poles. Getting ready to call the 
utilitly, only to soon discover a differnt pole that seems to be the 
culpret., or contributing to the other pole. One thing you could do is 
discribe the type of sound you hear to us, or compare sounds on  the website 
that catolouges  RFI sounds. ( cant recall the address) A very common ON/OFF 
RFI is caused by street lamps and the light sensor or bad bulb. In most 
cases it will only happen at night. But if its a bad sensor, then it will 
happen in the day. Drive around and look for a street light ON during the 
day. A flashing light ( 1 minute on 2 minutes off - kind of thing) is a SURE 
RFI generator.-day or night.

Good luck and why not MAKE a yagi for RFI hunting?  (  I use the tape 
measure yagi as featured in QST and on the web) You also need an 
anettenuator to cut down the overpowering rfi, especially if there is more 
than one source. I have used my VX5R in AM mode and work my way higher in 
frequecy as I get closer. But a better visual indicator other than the meter 
, is useful, like using an analouge meter hooked up to the speaker output. 
It is also best if you can turn off the AGC. You can  NOT do that with the 
VX5r unfortunatly. Without the attenuator, it is difficult, even by moving 
up in frequency as you get closer. A nearby noisy pole will still mix 
/overpower the pole you are ponited at, regardless of using a beam.

My main adivece is to really try  to QUALIFY what you are hearing and to go 
out and properly DETECT its location as certainly as possible. Beware of rfi 
that get "Coupled" into the long runs of the power line and coupled inside 
neighbours homes, then carried out to the street. Beware it not 2 differnt 
sources .Noise also will get coupled into anything metal such as long 
fences, guy wires, ALL overhead wires etc....that why the equipment ot 
really DETECT is important.

73 es GL...not much you prbably dont already know, but maybe just some 
incourgement. Things are even worse in Canada as Industry Canada actually no 
longer will consern themselves with RFO to hams...only emergency services 
like police .....otherwise, hams here are on are own to deal with 
uncoperative noisemakers! Can you believe it?!!


Original post by Ron W4LDE
> ----------Follow up !!! -------------------- 9-15-08 ------------------
> On 9-8 I contacted the local power company via email regarding the above, 
> unexpectedly
> I received a call from the Maintenance Manager who stated don't worry we 
> will be out
> maybe tomorrow and find the cause.  They did show up, two buck trucks and 
> full crews plus a 332-335 MHz Yagi and noise receiver.
> Unfortunately they said that they couldn't find anything and suggested it 
> might be from a neighbors home.
> They scanned my home but couldn't find a thing.
> I was one unhappy ham and expressed that they needed to keep looking.
> I believe I have ruled out a radio problem since the noise was about the 
> same on a FT-1000mp and a FT-847 and neither
> noise blanker would dent the noise.  A MFJ-Noise phasing unit helped some 
> but only improved the noise by about 1-2 S-units.
> I spent some time connecting and disconnecting home devices plus 
> disconnecting one house breaker at a time.
> Friday the 12th I decided that maybe I could help find the problem and 
> using a
> Yaesu VX-5R and rubber ducky at 134MHz and also at 329MHz AM started my 
> search.
> I found significant noise at three different power poles, all new ones, 
> with two west of my antenna about 1/8 mile and the other
> to the east at also about 1/8 mile.  So I thought I had found the problem 
> and would be reporting this condition today.
> When I came into the shack this AM to compose the email I happen to turn 
> on the rig and to my amazement the noise was gone.
> eleven days I had a Ham Radio Black out on the low bands.  Was I one happy 
> guy.  I thought I better go check out the poles.
> Off I went and yes the noise was gone at the poles, very quite.
> Went out later this afternoon and took the VX-5R, things were still quite 
> up and down the main road.
> After being gone for three hours as I was approaching the sub-division I 
> turned the
> VX-5R back on and WAM there was the same power poles and noise.  My heart 
> sunk, O-Sh_t I shouted and my XYL
> who understood the situation gave me her famous look and said keep on 
> looking, write the reflector they can help.
> Well after arriving home and one hour later in the shack I turned on the 
> radio and found NO significant noise.
> S-0 on 20-meters, S-2-3 on 30 meters and maybe as high as S-4 on 40M, at 
> 4PM thats not bad.
> I was amazed once again and kinda dumb founded as to were to look next if 
> I have to.
> Here's some of my thoughts,
> 1.  Today for the first time in the past few weeks we finally had a cool 
> day, high around 80 (occurred around 5PM)
> and a low tonight of 60
> a) Lower temps caused all connections to tighten and when it finally 
> warmed up around 4-5pm it started again at the poles.
> 2.  Since there is still home building going on near us as the crews were 
> leaving the construction site a week ago
> maybe they left chargers on for there power equipment and after doing 
> there thing finally turned them off this AM and left the site.
> 3.  I did find out that the telephone company was having lots of noise 
> problems
> from there own installation.  Not at my home but close.
> a) Can't believe thats the fix since the noise stopped early on Monday
> which didn't give them much time to complete the task, they started last 
> Wednesday.
> 4.  Cool days, less power consumed by the A/C units, less amps, less noise 
> (is it s stretch?)
> Ok I thought, maybe I should invest in a 144/440 hand held Yagi plus the 
> cables and adapters to help in a wider search
> area but wanted recommendations as to what I should be looking at if the 
> noise returns I would be using the VX-5r on 138 am MHz and 332 am MHz.
> Any thoughts are appreciated.
> I believe I have ruled out a radio problem since the noise was about the 
> same on a FT-1000mp and a FT-847 and neither
> noise blanker would dent the noise.  A MFJ-Noise phasing unit helped some 
> but only improved the noise by about 1-2 S-units.
> Any ideas where I should look next time and heres a pray that there isn't 
> one, is it worth the cost to invest now or wait?
> get a 114/440 Yagi or just stay with a 144 hand held Yagi.
> Thanks for the bandwidth and thoughts, wish I could take credit for the 
> current fix but I'm happy right now!
> 73 de
> Ron W4LDE

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