[RFI] Noise Level During Power Outage

[K9MA]

Don't be too envious, Pete.  Those levels are from the K4 panadapter 
with a 10 kHz span, which means a noise bandwidth of about 20 Hz. 
(Resolution bandwidth 11 Hz.) Besides, I have a power splitter and some 
other stuff between the receiver and the antenna, about 7 dB of loss, 
though I don't know where 4 of those dB come from. In any case, my 
"good" noise level on 20 of -130 dBm corresponds to about -110 dBm in a 
400 Hz bandwidth, about S-3 at 6 dB per S unit.

Pete is very close to a big transmission line. I have one of those a 
couple hundred meters away, but whatever noise it causes is always 
overwhelmed by noise from the distribution lines with which I'm surrounded.

73,
Scott


On 2/1/2023 8:25 AM, Pete Smith N4ZR wrote:
> I am green with envy - my local line noise is currently "only" S5
>
> 73, Pete N4ZR
>
> On 2/1/2023 12:26 AM, K9MA wrote:
>> That table didn't come out very well at all. Here's a link to the pdf:
>>
>> https://sdellington.us/hr/RFI/Power%20Outage.pdf
>>
>> 73,
>> Scott K9MA
>>
>> On 1/31/2023 11:21 PM, K9MA wrote:
>>> My QTH is in an older residential area, surrounded by overhead power 
>>> lines. Line noise is a constant problem. We recently had a major 
>>> power outage, so I measured the noise levels to get a baseline with 
>>> little line noise. (See below, assuming it comes through.) The 
>>> outage was pretty large: there was no power within a kilometer or 
>>> so, perhaps further to the west. The levels I measured shortly after 
>>> power was restored the next morning are fairly typical lately. To 
>>> the NE, it wasn't so bad, only increasing 5-8 dB when the power came 
>>> on. West was much worse, 7-19 dB. I've long known there was a major 
>>> noise source to the west. I guess it's time to track it down.
>>>
>>> I suspect these levels are fairly typical of a residential area with 
>>> overhead lines. They would probably be worse if I hadn't been doing 
>>> battle with the utility for the past 30 years to get the worst of 
>>> the sources fixed. One thing this data shows, which I've long 
>>> suspected, is that the distribution lines are the major source of 
>>> noise. There are some transmission lines just a few hundred meters 
>>> away, but I've never traced any significant noise to them.
>>>
>>> It may say something about the sad state of our utility's 
>>> infrastructure: A car knocked down a pole about 1 km from my QTH, 
>>> and it took out the power up to 2 km away, with power surges causing 
>>> extensive damage to appliances, etc. (None at my place.) Just down 
>>> the street, far from the downed pole, we had a major fireworks show 
>>> and nearby a transformer exploded. Apparently, similar things 
>>> happened throughout the affected area. Did they forget the fuses?
>>>
>>> 73,
>>>
>>> Scott K9MA
>>>
>>
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-- 
Scott  K9MA

k9ma at sdellington.us