Many thanks again to everyone who provided further suggestions and
encouragement on the noise problem: N4ICK, EI0CF, ZL3FJ, VK3GJZ, G4TMV,
G3YMC and GW4ALG. All comments are very much appreciated and useful in
getting to the bottom of this - I am wondering whether there may be some
mileage in compiling a collection of tips for tracking down noise on LF!
The latest situation hasn't changed much as I have been very busy again this
week, so have had little time to go out DFing. The noise is still running
continuously at S9 on 136kHz, but I did hear Dave G3YXM above it on Saturday
afternoon. Having checked with Dave that my TX frequency was clear, we had a
contact (my first on LF in 3 weeks!) which made a nice change, but the noise
was quite noticable even with Dave's monster signal, so I didn't attempt to
do anything else. I'm totally against using the band if you can't hear any
of the weaker signals - that just causes problems for everyone else......
To briefly answer a few points which were raised:
Yes, the poles where the noise peaked are definately telephone poles and
NOT power-line poles. It is very uncommon to have overhead power lines in
cities in England (although they are very common outside the cities). My
locality is typical of an English city suburb with no overhead power lines
at all (so I can't check them!) but LOTS of telephone poles. The local
transformer happens to be right outside the telephone exchange, but as
mentioned last time, the noise didn't show a peak anywhere in that immediate
area, and I'm not climbing over the fence to get in really close!
I happen to have a bat-detector, so if it is an arcing problem I am already
equipped to 'hear' it - nice suggestion that, Alan and Dave!
At Steve's suggestion, I used the Walkman to check for noise at our house
consumer box. Yes, it is louder there, but so are all the BC signals. The
noise is louder still where the central-heating pipes run up the wall and
into the loft (attic), so I think this is all just a re-radiation effect.
The most mystifying news is that the medium-wave noise appears to NOT be
local to me. On foot, I observed it getting weaker, but in the car driving
to work I discovered that it comes up again as you get further away and
there appears to be a fixed 'standing-wave' effect of peaks and troughs in
the noise. I could still hear it well on the car radio at work - 5 miles
away in the centre of the city! Now I have to investigate whether I am
confusing the issue by listening on medium wave - maybe that is a different
source from my 136kHz problem? If not, it's one heck of a noise source.....
More when I have it!
John G4GVC near Leicester, IO92JP
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