How long did you wait?
Most devices spool down quickly but not all. It is not too common, but
I have seen a few devices using internal DC-DC converters where the
secondary converter will keep generating noise for several minutes after
AC loss if there is no load on the output.
One of my neighbors had a scooter charger that look almost 5 minutes to
go silent if there was go scooter connected (big buffer cap feeding the
pulse charge circuit after the first switcher).
Seen a couple of PC supplies that look 2 - 3 minutes if the computer was
in stby when AC was lost.
On 9/14/12 12:18 PM, Tony wrote:
> On 9/13/2012 11:32 PM, Wes Attaway (N5WA) wrote:
>> Do you have outside lighting that turns on during the time period in
>> question?
>
> I do but the noise persists with that breaker turned off. I even took
> the light off the house and disconnected it just to make sure.
>
> Tony
>
>
>>
>> ----------------- Wes Attaway (N5WA) -------------------
>> 1138 Waters Edge Circle, Shreveport, LA 71106
>> 318-797-4972 (Office) - 318-393-3289 (Cell)
>> Computer Consulting and Forensics
>> -------------- EnCase Certified Examiner ---------------
>>
>>
>> -----Original Message-----
>> From: RFI [mailto:rfi-bounces@contesting.com] On Behalf Of Tony
>> Sent: Thursday, September 13, 2012 10:09 PM
>> To: Rfi List
>> Subject: Re: [RFI] Noise changes when room lights turn on / off UPDATE
>>
>> All:
>>
>> Just an update on the noise:
>>
>> Turned off all breakers in the house except for one that powers a single
>> A/C outlet in the shack. The noise was still there. Friend has not come
>> through with his battery powered HF rig so I might just by a small 12
>> volt so I can run the rig with the main breaker turned off.
>>
>> To recap:
>>
>> - noise appears each night between 7PM and 8 PM.
>> - Continues intermittently until morning and is not heard during the day
>> - it sounds similar to line noise. It's wide-band about 30khz in width
>> - It appears every 120 kHz on several HF bands.
>> - noise shifts in frequency when shack light is turned on / off using
>> house switch
>> - shack light is not the source of the noise. It's there with the light
>> unplugged
>> - noise appears on a heading that is beaming away from my QTH
>>
>> Noise video - http://www.youtube.com/watch?v=EYHbpLfQ1gc
>>
>> Thanks,
>>
>> Tony -K2MO
>>
>>
>>
>>
>> -
>>
>>>> All:
>>>>
>>>> The noise that appeared this evening at 7:00pm may have something to
>>> do with AC power coming into the house. I noticed that the noise
>>> changed when I turned the shack light on and off. This video shows
>>> what happens: http://www.youtube.com/watch?v=EYHbpLfQ1gc
>>>> There are no florescent lights or touch lamps in the house.
>>> Unplugging the shack light does not make the noise go away. Turning
>>> the shack's light switch on or off with the light unplugged does not
>>> change the noise. The noise persists with power supplies, computers
>>> and TV's turned off or unplugged.
>>>> I'll investigate further and report back tomorrow.
>>>>
>>>> Thanks,
>>>>
>>>> Tony -K2MO
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>>
>>
>
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