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HF interference
Posted: Fri Jan 04, 2013 10:35 am
by VK3RX
The last couple of days I've been experiencing S9+ interference on 40m.
No additional appliances here or anything changed. I shut off all power to the premises, and the noise is still there on a battery-powered HF set. No solar panels installed by immediate neighbours.
It is very broad, ranging from below 7MHz to above 8MHz. Antenna is resonant around 7.1MHz but the noise seems to peak about 7.5MHz.
Below is an audio clip around 7.085 and a pix of the audio trace. As yet I haven't checked at night to see if it is still there.
Occasionally instead of the 10 pulses there may only be a couple.
Anyone heard this before?
Re: HF interference
Posted: Fri Jan 04, 2013 1:52 pm
by VK3QI
Damien,
Check to see if all your street lights are switching off/on properly.
Depending on your location, some street lights are controlled together by one photocell and in other areas, individual lights have their own photocells. Quite often dust or some other fault can cause the individulal units to not switch properly for hours on end.
Cheers
Peter VK3QI
Re: HF interference
Posted: Fri Jan 04, 2013 1:58 pm
by VK3BGS
Do you have HFC cable services at your place.?
The clicking sound is close to what I have experienced, but is somewhat different also.
Have a look at my posts under "15 meter interference" in this forum.
PM me if you wish.
Denis VK3BGS
Re: HF interference
Posted: Fri Jan 04, 2013 2:12 pm
by VK2GOM
I'd be interested to hear if anyone can pinpoint exactly what it is, since its one of the myriad interference noises I get here too.
73 - Rob VK2GOM / GW0MOH
Re: HF interference
Posted: Fri Jan 04, 2013 2:40 pm
by VK3RX
G'day Denis - only ADSL here, no HFC in this area I am aware of. I had a look over all the posts including yours but couldn't find anything similar.
Today it was bad all morning but after about midday it disappeared. I can't recall if the same happened yesterday or not.
Peter: Thanks for the tip re street lights. I'll keep an eye out for that.
I'll monitor it over the next few days and report back.
Re: HF interference
Posted: Fri Jan 04, 2013 3:20 pm
by VK3BGS
I used a portable shortwave radio as a "sniffer", worked well.
Started here in the shack and just kept on going until I found the offending interference getting louder.
My original thought it might be a "smart meter", lucky it wasn't I guess.
You are right though, there is just "so" much rf crap around and unfortunately its going to get worse.
It finally took me about 6 weeks from when I first started investigating my issue and I admit I got lucky with a web search, which helped a lot.
It probably is not far from you front door either.
Best of luck.
Denis
VK3BGS